Kumar A, Saroj DP, Tare V, Bose P (2006) Treatment of distillery spent-wash by ozonation and biodegradation: significance of pH reduction and inorganic carbon removal before ozonation., Water Environ Res 78 (9) pp. 994-1004 Water Environment Federation
This study is aimed at exploring strategies for mineralization of refractory compounds in distillery effluent by anaerobic biodegradation/ozonation/aerobic biodegradation. Treatment of distillery spent-wash used in this research by anaerobic-aerobic biodegradation resulted in overall COD removal of 70.8%. Ozonation of the anaerobically treated distillery spent-wash was carried out as-is (phase I experiments) and after pH reduction and removal of inorganic carbon (phase II experiments). Introduction of the ozonation step resulted in an increase in overall chemical oxygen demand (COD) removal, with the highest COD removals of greater than 95% obtained when an ozone dose of approximately 5.3 mg ozone absorbed/mg initial total organic carbon was used. The COD removal during phase II experiments was slightly superior compared with phase I experiments at similar ozone doses. Moreover, efficiency of ozone absorption from the gas phase into distillery spent-wash aliquots was considerably enhanced during phase II experiments.
Saroj DP, Kumar A, Bose P, Tare V (2006) Enhancement in mineralization of some natural refractory organic compounds by ozonation-aerobic biodegradation, JOURNAL OF CHEMICAL TECHNOLOGY AND BIOTECHNOLOGY 81 (2) pp. 115-127 JOHN WILEY & SONS LTD
Municipal wastewater is often treated at a centralized treatment facility based on Activated Sludge Process (ASP) where the production of (excess) activated sludge (bio-solids) is mostly not desired and further sludge handling often contributes to a large fraction of the total operational cost, depending upon the applicable legislation and/or sludge treatment and disposal practices. Further, the Biological Nutrient Removal (BNR) based on ASPs often pose extra cost due to the need for external carbon source (acetate, methanol etc.) for the optimal performance of denitrification and biological phosphorous removal. In this research, the excess sludge was ozonated and the filtrates were used in activity batch tests for anaerobic P-release, aerobic P-uptake and denitrification. Experimental results have shown that the ozone dose in the range of 0.1-0.2 g O3/g MLSS leads to a good degree of bio-solids destruction (sludge reduction) resulting in highly biodegradable organics. The use of ozonated sludge at those ozone doses as carbon source in the activity tests revealed that the soluble biodegradable organics can be successfully used for improved denitrification and biological P-uptake. Further, the process cost analysis showed the economic feasibility under complete sludge treatment scenario, where about 42% of sludge reduction is achieved and about 30% of the total operational cost reduction may be possible under assumed conditions.
Akhigbe L, Ouki S, Saroj DP, Lim XM (2014) Silver-modified clinoptilolite for the removal of Escherichia coli and heavy metals from aqueous solutions, Environmental Science and Pollution Research
Saroj DP, Inchauste-Daza A, Lopez-Vazquez CM (2013) Simultaneous Sludge Disintegration and Carbon Source Generation for Enhanced Biological Phosphorous Removal Using Ozonation, WEF 2013
Sadr SMK, Mashamaite I, Saroj DP, Ouki S, Ilemobade A (2015) Membrane assisted technology appraisal for water reuse applications in South Africa, Urban Water Journal
Water scarcity, pertaining to many interrelated issues e.g. rapid urbanisation and increasing water pollution, has been acknowledged around the world. Water reuse has emerged as a viable water conservation measure to satisfy water demand in many communities. Among the diversity of wastewater treatment processes, membrane assisted treatment technologies have been employed for different water reuse scenarios. In this regard, one of the most critical problems is how to select an appropriate membrane technology for a water reuse scenario. This research therefore develops a decision making framework for selection of wastewater treatment technology. The framework is applied to different non-potable reuse scenarios in South African cities and suburban areas by employing a multi criteria analysis method. The results show that this approach is able to provide a systematic and rigorous analysis which can help in comparing and selecting wastewater technologies.
Nitrification is an integral part of biological nitrogen removal processes and usually the limiting step in wastewater treatment systems. Since nitrification is often considered not feasible at temperatures higher than 40 °C, warm industrial effluents (with operating temperatures higher than 40 °C) need to be cooled down prior to biological treatment, which increases the energy and operating costs of the plants for cooling purposes. This study describes the occurrence of thermophilic biological nitrogen removal activity (nitritation, nitratation, and denitrification) at a temperature as high as 50 °C in an activated sludge wastewater treatment plant treating wastewater from an oil refinery. Using a modified two-step nitrification-two-step denitrification mathematical model extended with the incorporation of double Arrhenius equations, the nitrification (nitrititation and nitratation) and denitrification activities were described including the cease in biomass activity at 55 °C. Fluorescence in situ hybridization (FISH) analyses revealed that Nitrosomonas halotolerant and obligatehalophilic and Nitrosomonas oligotropha (known ammonia-oxidizing organisms) and Nitrospira sublineage II (nitrite-oxidizing organism (NOB)) were observed using the FISH probes applied in this study. In particular, this is the first time that Nitrospira sublineage II, a moderatedly thermophilic NOB, is observed in an engineered full-scale (industrial) wastewater treatment system at temperatures as high as 50 °C. These observations suggest that thermophilic biological nitrogen removal can be attained in wastewater treatment systems, which may further contribute to the optimization of the biological nitrogen removal processes in wastewater treatment systems that treat warm wastewater streams.
Saroj DP, Guglielmi G, Chiarani D, Andreottola G (2008) Modeling and simulation of membrane bioreactors by incorporating simultaneous storage and growth concept: an especial attention to fouling while modeling the biological process, Desalination 221 (1-3) pp. 475-482
The major obstacle for membrane bioreactors (MBRs) to become a widely applicable technology is the membrane fouling. Despite the fact that the fouling is inevitable, understanding of the inherent mechanisms and subsequent integrated modeling of the process seems greatly helpful for optimization and control. Several researches have shown the importance of extra-cellular polymeric substances (EPS) their role in explaining the two-step with sudden jump in TMP vs. time. But, the crucial point remains about the prediction of the EPS concentration in the dynamic MBR sludge matrix and the research attention becomes bit more on biological behavior of the sludge matrix in order to have 'an integrated complete dynamic model' describing both filtration and biological behavior simultaneously. Moreover, on account of operational and fundamental difference from conventional wastewater treatment processes, MBRs possess distinct biological dynamics and hence the activated sludge models (ASMs: ASM1, ASM3, etc. ) in their original form are not expected to be workable. Therefore, the two-fold idea has been suggested and used for simulation herein are (i) improved version of ASM3 as suggested by Sin et al.  seems promising in order to explain the distinct MBR biological process dynamics, and (ii) EPS model which has a strong urge to be used as input to fouling model. The notion of 'complete model' provides a platform to infuse the researches from two different fields viz. biological process modeling and filtration modeling for MBRs application in a harmonized way and hence provokes interconnected investigations from both the fields. © 2008.
Naz I, Khatoon N, Ali MI, Batool SA-U, Ali N, Ahmed S, Saroj DP (2013) Appraisal of the tire derived rubber (TDR) medium for wastewater treatment under aerobic and anaerobic conditions, Journal of Chemical Technology and Biotechnology
BACKGROUND: The present study evaluated the effectiveness and durability of tire derived rubber (TDR) for biofilm development and related long term use in fixed biofilm reactors for wastewater treatment. RESULTS: TDR incubated (30±2°C) with activated sludge showed comparatively higher biofilm development (0.51g) under aerobic than under anaerobic (0. 42g) conditions after 7weeks. During biofilm succession, a significant shift in bacterial community was observed from pathogenic to autotrophic after 4weeks. The decreasing bacterial count (MPN index) (H80%) (Escheria coli and feacal coliforms) and chemical oxygen demand (COD), and biological oxygen demand (BOD) (70% approx.) depicted diminishing organic load in sludge. Changes in pH and nutrients like NO
indicated presence of other key bacterial species with efficient nutrient consuming abilities in biofilm. Scanning electron microscopy showed few aberration and rich bacterial growth on treated TDR. Furthermore, detailed analysis through Fourier transform infrared (FTIR) spectroscopy confirmed minor transformation in TDR under anaerobic conditions. CONCLUSION: TDR proved to be a durable and cost effective support material that can be used in aerobic fixed biofilm reactors for wastewater treatment. However, operational conditions of the reactor should be optimized to keep the biofilm structure intact and to achieve the desired wastewater treatment efficiency. © 2013 Society of Chemical Industry.
This research compares and contrasts the physical and chemical characteristics of incinerator sewage sludge ash (ISSA) and pyrolysis sewage sludge char (PSSC) for the purposes of recovering phosphorus as a P-rich fertiliser. Interest in P recovery from PSSC is likely to increase as pyrolysis is becoming viewed as a more economical method of sewage sludge thermal treatment compared to incineration. The P contents of ISSA and PSSC are 7.2?7.5% and 5.6%, respectively. Relative to the sludge, P concentrations are increased about 8-fold in ISSA, compared to roughly 3-fold in PSSC. Both PSSC and ISSA contain whitlockite, an unusual form of calcium phosphate, with PSSC containing more whitlockite than ISSA. Acid leaching experiments indicate that a liquid/solid ratio of 10 with 30 min contact time is optimal to release PO4-P into leachate for both ISSA and PSSC. The proportion of P extracted from PSSC is higher due to its higher whitlockite content. Heavy metals are less soluble from PSSC because they are more strongly incorporated in the particles. The results suggest there is potential for the development of a process to recover P from PSSC.
The occurrence of emerging or newly identified contaminants in water resources is becoming a great concern for public health. The worldwide freshwater scarcity is also increasing. These have resulted in rapid growth in the demand for nonconventional water resources and sophisticated approaches to wastewater treatment. Existing conventional water treatment plants were not designed for these emerging contaminants. Therefore, new approaches to wastewater treatment are required. Among the most promising processes for various types of wastewater treatment and water reuse, membrane-assisted technologies have been accepted as suitable and reliable in different applications of water reuse. This chapter discusses the application of membrane processes and membrane-assisted technologies in wastewater treatment and water reuse. The chapter mainly focuses on membrane bioreactors (MBRs), including a comparison between conventional activated sludge processes and MBRs. Emerging membrane-assisted technologies are also discussed.
Naz I, Saroj DP, Mumtaz S, Ali N, Ahmed S (2015) Assessment of biological trickling filter systems with various packing materials for improved wastewater treatment, Environmental technology 36 (1-4) pp. 424-434
Attached growth processes for wastewater treatment have significantly been improved during recent years. Their application can be extended to sustainable municipal wastewater treatment in remote locations and in developing countries for the purpose of organic matter (biochemical oxygen demand, BOD) removal and pathogenic decontamination. The aim of this study is to assess selected packing media for biological trickling filters (BTFs) and to develop a simplified model for describing the capacity of BOD removal in BTFs. In this work, BTFs with four different media viz., rubber, polystyrene, plastic and stone have been investigated at two temperature ranges of 5-15°C and 25-35°C. The average removal of both chemical oxygen demand and BOD was higher than 80 and 90% at temperature ranges of 5-15 and 25-35°C, respectively. The geometric mean of faecal coliforms in BTF using polystyrene, plastic, rubber and stone as filter media was reduced by 4.3, 4.0, 5.8 and 5.4?log10, respectively, at a low temperature range of 5-15°C. At a higher temperature range of 25-35°C, the faecal coliform count was reduced by 3.97, 5.34, 5.36 and 4.37?log10 from polystyrene, plastic, rubber and stone media BTF, respectively. Simplified model was developed and used to estimate the optimal BOD loading rates (Bvd) for designing robust BTF systems, with appropriate filter media. It has been concluded that highly efficient BTFs can be designed using various filter media, which may be capable of treating organic loading rates of more than 3?kg BOD/m3 day. These types of BTFs can be applied for the BOD and microbial contaminants removal of wastewater for potential reuse in developing countries.
A large pilot-scale membrane bioreactor (MBR) with a conventional denitrification/nitrification scheme for municipal wastewater treatment has been modelled with an extended version of ASM3 available in the literature, according to which heterotrophic biomass growth occurs on both readily biodegradable COD and storage products. The model has been regularly calibrated by means of respirometric techniques and validated against experimental data of MLSS concentration in the biotank, effluent COD and nitrogen forms. The applied model was able to fairly predict the routinely monitored effluent quality (COD, NH4-N and NO3-N) and sludge production. The model appears to be suitable for improved biological process modelling of MBRs, leading to better process optimization of MBRs for municipal wastewater treatment.
Fenu A., Guglielmi G., Jimenez J., Sperandio M., Saroj D. P., Lesjean B., Brepols C., Thoeye C., Nopens I. (2011) Activated Sludge Model-Based Modeling of Membrane Bioreactor Processes: A Critical Review with Special Regard to MBR Specificities,In: Moo-Young M (eds.), Environmental Biotechnology and Safety 6 pp. 305-327
Saroj DP, Kumar A, Bose P, Tare V, Dhopavkar Y (2005) Mineralization of some natural refractory organic compounds by biodegradation and ozonation, Water Research 39 (9) pp. 1921-1933
Guglielmi G, Saroj DP, Chiarani D, Andreottola G (2007) Sub-critical fouling in a membrane bioreactor for municipal wastewater treatment: experimental investigation and mathematical modelling., Water Res 41 (17) pp. 3903-3914
Fouling is a major limitation for the application of membrane bioreactors (MBRs) in municipal wastewater treatment; the critical flux concept represents a valid tool for process optimisation in planning fouling control strategies. The paper presents the results obtained on a large pilot MBR equipped with a plate-and-frame ultrafiltration membrane. The experimental assessment of flux criticality was carried out by flux-stepping tests showing the positive impact of liquid temperature on the value of the critical threshold. The reliability of short-term tests was then verified over a long period by determining the time of sustainability, t(sust), of six different sub-critical fluxes ranging between 17 and 30Lm(-2)h(-1). An exponential fitting was observed in terms of fouling rate both before and after t(sust), though fouling after t(sust) is likely to be ascribed not only to cake formation. Finally, a new mathematical formulation was proposed according to the local flux approach to model the sub-critical TMP transients. The model involves both bound and free forms of EPS and, once experimentally calibrated, it provided a fair prediction of the TMP jump.
This review concentrates on the effect of activated carbon (AC) addition to membrane bioreactors (MBRs) treating wastewaters. Use of AC-assisted MBRs combines adsorption, biodegradation and membrane filtration. This can lead to advanced removal of recalcitrant pollutants and mitigation of membrane fouling. The relative contribution of adsorption and biodegradation to overall removal achieved by an AC-assisted MBR process can vary, and ?biological AC? may not fully develop due to competition of target pollutants with bulk organics in wastewater. Thus periodic replenishment of spent AC is necessary. Sludge retention time (SRT) governs the frequency of spent AC withdrawal and addition of fresh AC, and is an important parameter that significantly influences the performance of AC-assisted MBRs. Of utmost importance is AC dosage because AC overdose may aggravate membrane fouling, increase sludge viscosity, impair mass transfer and reduce sludge dewaterability.
Lopez-Vazquez CM, Kubare M, Chikamba C, Brdjanovic D, Saroj DP, Schwarz J, Daims H (2014) Thermophilic biological nitrogen removal in industrial wastewater treatment, Applied Microbiology and Biotechnology 98 (2) pp. 945-956
Nitrification is an integral part of biological nitrogen removal processes and usually the limiting step in wastewater treatment systems. Since nitrification is often considered not feasible at temperatures higher than 40 C, warm industrial effluents (with operating temperatures higher than 40 C) need to be cooled down prior to biological treatment, which increases the energy and operating costs of the plants for cooling purposes. This study describes the occurrence of thermophilic biological nitrogen removal activity (nitritation, nitratation, and denitrification) at a temperature as high as 50 C in an activated sludge wastewater treatment plant treating wastewater from an oil refinery. Using a modified two-step nitrification-two-step denitrification mathematical model extended with the incorporation of double Arrhenius equations, the nitrification (nitrititation and nitratation) and denitrification activities were described including the cease in biomass activity at 55 C. Fluorescence in situ hybridization (FISH) analyses revealed that Nitrosomonas halotolerant and obligatehalophilic and Nitrosomonas oligotropha (known ammonia-oxidizing organisms) and Nitrospira sublineage II (nitrite-oxidizing organism (NOB)) were observed using the FISH probes applied in this study. In particular, this is the first time that Nitrospira sublineage II, a moderatedly thermophilic NOB, is observed in an engineered full-scale (industrial) wastewater treatment system at temperatures as high as 50 C. These observations suggest that thermophilic biological nitrogen removal can be attained in wastewater treatment systems, which may further contribute to the optimization of the biological nitrogen removal processes in wastewater treatment systems that treat warm wastewater streams. © 2013 Springer-Verlag Berlin Heidelberg.
Ojajuni O, Saroj DP, Cavalli G (2015) Removal of organic micropollutants using membrane assisted processes: a review of recent progress, Environmental Technology Reviews
The health risk of organic micro pollutants in water is yet to be comprehensively established. However, the persistence of these pollutants in the environment as a result of continuous discharge even at trace concentrations is considered to pose
major environmental concerns. Advance treatment methods such as membrane-assisted processes (MAPs) are potential technologies capable of removing a wide range of these organic micropollutants (OMPs) detected in water. Tight membranes as regards pore size are reported to be more efficient than loose membranes mainly because of the removal mechanism
involved, which is mainly influenced by the properties of the membrane and the pollutants in relation to solute?solute and
solute?membrane interaction. The study and application of membrane processes to water and wastewater treatment have grown significantly in the last decade. Membrane processes application is diverse and flexible enough to allow adaptation
into other physicochemical processes. Integration and hybridization of membrane processes with other physicochemical processes and natural systems are becoming a more economical and sustainable option for removal of OMPs. Nevertheless, there are shortfalls in the industrial application of membrane-assisted technologies. This paper reviews and assesses the applicability of various MAPs applied for the removal of OMPs from water and wastewater streams.
Akhigbe L, Ouki S, Saroj DP (2014) Removal of Escherichia coli and heavy metals from
aqueous solutions using silver-modified clinoptilolite, Desalination and Water Treatment
Naz I, Seher S, Perveen I, Saroj DP, Ahmed S (2015) Physiological activities associated with biofilm growth in attached and suspended growth bioreactors under aerobic and anaerobic conditions, Environmental Technology (United Kingdom) 36 (13) pp. 1657-1671
© 2015 Taylor & Francis.This research work evaluated the biofilm succession on stone media and compared the biochemical changes of sludge in attached and suspended biological reactors operated under aerobic and anaerobic conditions. Stones incubated (30 ± 2°C) with activated sludge showed a constant increase in biofilm weight up to the fifth and seventh week time under anaerobic and aerobic conditions, respectively, where after reduction (>80%) the most probable number index of pathogen indicators on ninth week was recorded. Reduction in parameters such as biological oxygen demand (BOD) (47.7%), chemical oxygen demand (COD, 41%), nitrites (60.2%), nitrates (105.5%) and phosphates (58.9%) and increase in dissolved oxygen (176.5%) of sludge were higher in aerobic attached growth reactors as compared with other settings. While, considerable reductions in these values were also observed (BOD, 53.8%; COD, 2.8%; nitrites, 28.6%; nitrates, 31.7%; phosphates, 41.4%) in the suspended growth system under anaerobic conditions. However, higher sulphate removal was observed in suspended (40.9% and 54.9%) as compared with biofilm reactors (28.2% and 29.3%). Six weeks biofilm on the stone media showed maximum physiological activities; thus, the operational conditions should be controlled to keep the biofilm structure similar to six-week-old biofilm, and can be used in fixed biofilm reactors for wastewater treatment.
This study investigates the microbial community composition, in the biofilms grown on two different support media in fixed biofilm reactors for aerobic wastewater treatment, using next generation sequencing (NGS) technology.The chemical composition of the new type of support medium (TDR) was found to be quite different from the conventionally used support medium (Stone).The analysis of 16S rRNA gene fragments recovered from the laboratory scale biofilm system show that biofilm support media and temperature conditions in?uence bacterial community structure and composition. Greater bacterial diversity was observed under each condition, primarily due to the large number of sequences available and sustenance of rare species. There were 6 phyla found, with the highest relative abundance shown by the phylum Proteobacteria (52.71%) followed by Bacteroidetes (33.33%), Actinobacteria (4.65%), Firmicutes, Verrucomicrobia (3.1%) and Chloroflex (>1%). The dataset showed 17 genera of bacterial populations to be commonly shared under all conditions, suggesting the presence of a core microbial community in the biofilms for wastewater treatment. However, some genera in the biofilms on TDR were observed in high proportions, which may be attributed to its chemical composition, explaining the improved level of wastewater treatment. The findings show that the structure of microbial communities in biofilm systems for wastewater treatment is affected by the properties of support matrix.
Membrane bioreactors (MBRs) have been increasingly employed for municipal and industrial wastewater treatment in the last decade. The efforts for modelling of such wastewater treatment systems have always targeted either the biological processes (treatment quality target) as well as the various aspects of engineering (cost effective design and operation). The development of Activated Sludge Models (ASM) was an important evolution in the modelling of Conventional Activated Sludge (CAS) processes and their use is now very well established. However, although they were initially developed to describe CAS processes, they have simply been transferred and applied to MBR processes. Recent studies on MBR biological processes have reported several crucial specificities: medium to very high sludge retention times, high mixed liquor concentration, accumulation of soluble microbial products (SMP) rejected by the membrane filtration step, and high aeration rates for scouring purposes. These aspects raise the question as to what extent the ASM framework is applicable to MBR processes. Several studies highlighting some of the aforementioned issues are scattered through the literature. Hence, through a concise and structured overview of the past developments and current state-of-the-art in biological modelling of MBR, this review explores ASM-based modelling applied to MBR processes. The work aims to synthesize previous studies and differentiates between unmodified and modified applications of ASM to MBR. Particular emphasis is placed on influent fractionation, biokinetics, and soluble microbial products (SMPs)/exo-polymeric substances (EPS) modelling, and suggestions are put forward as to good modelling practice with regard to MBR modelling both for end-users and academia. A last section highlights shortcomings and future needs for improved biological modelling of MBR processes.
The problem of fresh water scarcity is becoming a global issue, due to rapid urbanisation, population growth, water pollution, climate change and compounded effects. The incorporation of water reuse in upcoming urban water systems will not only satisfy a large part of water demand but also create a situation where wastewater treatment will be essential due to accountability towards the end users of water reuse. There are various technical and non-technical challenges towards the conceptualisation and materialisation of water reuse for a sustainable urban water system. The selection of appropriate technologies for a specific urban settlement is one of the key challenges. A plethora of existing technologies, such as membrane assisted technologies, for wastewater treatment and reuse may pose difficulty in decision making. Decision makers, such as water authorities and industries, often come across a lot of information and facts for a variety of technologies and reuse concepts. A systematic analysis of available technologies and options is necessary in order to increase the chances of success in wastewater reuse projects. Multi-criteria analysis (MCA) is a decision making method for systematic appraisal of wastewater reuse technologies. In this research the MCA has been carried out for the ranking of candidate technologies, after incorporating all the factors in terms of numerical values. Eight membrane assisted technologies have been short-listed due to their suitability under considered water reuse scenarios. Subsequently, most relevant technology selection criteria have been assessed. The MCA based ranking of candidate technologies provides a relative indication of the suitability of various membrane assisted water reuse technologies. It has been concluded that a systematic and rigorous analysis of candidate technologies can help decision makers to compare various available technological options and select the best available option for a sustainable water reuse concept.
Dwindling supplies of fossil fuel along with detrimental release of greenhouse gases have led to the quest for renewable sources of fuel such as bioethanol from cellulosic materials. Conversion of biomass to bioethanol involves a set of ?biotransformation? and ?recovery/concentration? processes. With the help of membrane technology, several process steps that were conventionally separate can be integrated and the production of bioethanol simplified. In addition to efficient recovery of bioethanol, this can facilitate removal of inhibitory side products from the fermentation broth and recovery of the inhibitory but valuable side products. This chapter provides a critical review of the application of membrane technology in various steps of bioethanol production. The challenges to widespread deployment of full-scale bioethanol facilities equipped with membranes have also been outlined.
Saroj DP, Guglielmi G, Chiarani D, Andreottola G (2008) Subcritical fouling behaviour modelling of membrane bioreactors for municipal wastewater treatment: The prediction of the time to reach critical operating condition, DESALINATION 231 (1-3) pp. 175-181 ELSEVIER SCIENCE BV
The physical properties of excess sludge wasted from a large pilot scale membrane bioreactor (MBR) have been routinely monitored over almost two years. A statistical analysis highlighted the significant impact of temperature on the capillary suction time and sludge filterability, due to the increase of organic matter in the liquid phase. Suspended solids have resulted to be the most important component affecting sludge filterability, although the impact of colloids and solutes increased when temperature decrease, thus confirming the generally worse characteristics of sludge in such conditions. Conditioning and dewatering test have been performed on a pilot scale fixed volume recessed plate filter press. Six different chemicals were used for sludge pre-conditioning and, for each additive, three dosages were tested in the range 5-25 gpolymer kgMLSS- 1. After about sixty filtration trials at three different pressure values (7, 11 and 15 bar), the kind of polymer seem to be the most important factor influencing the final cake-dryness, with less evident impact for dosage and operational pressure. Finally, when performed on the aerobically digested excess sludge wasted from a conventional activated sludge plant, the filtration tests show no differences with the MBR sludge. © 2009 Elsevier B.V. All rights reserved.
Wilson SP, Ouki SK, Saroj DP, Pearce PA, Bancroft L, Germain E (2015) Adopting primary plastic trickling filters as a solution for enhanced nitrification., Water Environ Res 87 (1) pp. 80-87
The wastewater industry is under pressure to optimize performance of sewage treatment works (STW), while simultaneously reducing energy consumption. Using a process configuration selection matrix, this paper explores the practicability of placing a hypothetical cross flow structured plastic media (CFSP) trickling filter (TF) immediately ahead of an existing conventional trickling filter process (CTFP), without intermediate clarification. The viability of this configuration is subsequently demonstrated using an empirical multispecies TF model. This predicts the enhanced nitrification performance of the CTFP by simulating prior removals of biochemical oxygen demand (BOD). The model predictions propose that prior 50-80% BOD removals can allow for further reductions in effluent ammoniacal nitrogen (NH4-N) concentrations of 40-70%, respectively. This illustrates that adopting low energy TF technologies can eliminate the requirement for more energy intensive alternatives, such as submerged aerated filters (SAF). Moreover, this configuration maximizes the potential of existing assets, while simultaneously improving nitrification robustness when compared with tertiary nitrification processes.
Kumar P, Saroj DP (2013) Water-energy-pollution nexus for growing cities, Urban Climate
Most recognised global challenges of modern times are related to energy production and consumption. The trends of energy demand for a growing world population and global urbanisation have raised serious concerns, and they are often termed as "global challenges" that include climate change, pollution and demands of clean water, food and energy. In thematic debate of the 2013 UN General Assembly in New York on "Sustainable Development and Climate Change: Practical Solutions in the Energy-Water Nexus" it was highlighted that adequate attention should be given to the importance of inter-linkages between water and energy sectors in framing the post-2015 development agenda. In fact, the implications of energy consumption in the modern world go beyond these boundaries. Therefore we argue that there is a need for establishing a broader nexus - "water-energy-pollution" - where implications of energy production, related water consumption and environmental pollution (air and water) are embedded. The notion of this integrated nexus can play an important role in systemic appraisal of energy production and consumption in growing urban environments. © 2014 Elsevier B.V.
Guglielmi G, Chiarani D, Saroj DP, Andreottola G (2008) Impact of chemical cleaning and air-sparging on the critical and sustainable flux in a flat sheet membrane bioreactor for municipal wastewater treatment., Water Sci Technol 57 (12) pp. 1873-1879
The paper discusses the experimental optimisation of both chemical and mechanical cleaning procedures for a flat-sheet submerged membrane bioreactor fed with municipal wastewater. Fouling was evaluated by means of the critical flux concept, which was experimentally measured by short-term flux-stepping tests. By keeping constant most important parameters of the biological process (MLSS, sludge age), two different chemical cleaning protocols (2,000 mg L(-1) NaOCl and 200 mg L(-1) NaOCl) were applied with different frequency and, after approximately 9 months of operation, the criticality threshold was determined under different values of SAD(m) (specific aeration demand per unit of membrane surface area). The weaker and more frequent chemical cleaning regime (200 mg L(-1), monthly) proved much more effective than the stronger and less frequent strategy (2,000 mg L(-1), once every three months). The improvement of performances was quantified by two TMP-based parameters, the fouling rate and the DeltaTMP (difference between TMP values during the increasing and decreasing phase of hysteresis). The best performing configuration was then checked over a longer period by running four long-term trials showing an exponential trend of the sub-critical fouling rate with the imposed flux.
This study investigates the simultaneous removal of Escherichia coli and metals (Pb, Cd and Zn) in a continuous flow system and provides an insight into the mechanisms involved during bacterial cells kill when in contact with silver-modified zeolite. Results showed complete disinfection and metal removal at 570 min contact time, thereafter E. coli breakthrough followed by Cd and Zn at 1080 min. Due to the zeolite?s high selectivity for Pb removal, no breakthrough was observed up to 7920 min run time. Column performance was influenced by changes in flow rate and bed height, as breakthrough occurred at 240 min when the flow rate was increased from 2 to 5 mL/min and the bed height decreased from 1 to 0.5 cm. Morphological characterization of treated cells revealed extensive damage and synthesis of nano- and micro-sized silver particles as a part of their defence mechanism. The treated effluent was passed through a non-modified zeolite column with 98% silver recovery achieved. This study showed the capability of this system to simultaneously handle bacterial and heavy metals contamination while providing an insight into the mechanism of disinfection via complex E. coli-silver ion interactions that occur during treatment and demonstrating the potential of silver recovery for reuse.
The present study evaluated the effectiveness and durability of TDR for biofilm development and related long term usage in fixed biofilm reactors for wastewater treatment. TDR incubated (30±2ºC) with activated sludge showed comparatively higher biofilm development (0.51g) under aerobic than under anaerobic (0. 42g) conditions after 7 weeks. During biofilm succession, a significant shift in bacterial community was observed from pathogenic to autotrophic after 4 weeks. The decreasing bacterial count (MPN index) ( 80%) (E .coli and feacal coliforms) and COD, and BOD (70% approx.) depicted diminishing organic load in sludge. While, changes in pH and nutrients like NO2-, NO3-, PO43-and SO32- indicated presence of other key-bacterial species with efficient nutrient consuming abilities in biofilm. Scanning Electron Microscopy showed few aberration and rich bacterial growth on treated TDR. Furthermore, detailed analysis through FTIR spectroscopy confirmed minor transformation in TDR under anaerobic conditions. TDR proved to be considerably durable and cost effective support material that can be used in aerobic fixed biofilm reactors for wastewater treatment. However, operational conditions of the reactor should be optimized to keep the biofilm structure intact and for achieving desired wastewater treatment efficiency.
Skouteris George, Ouki Sabeha, Foo Dominic, Saroj Devendra, Altini Maria, Melidis Paraschos, Cowley Brian, Ells Geoff, Palmer Stephanie, O'Dell Sean (2018) Water footprint and water pinch analysis techniques for sustainable water management in the brick-manufacturing industry,Journal of Cleaner Production 172 pp. 786-794
Brick-manufacturing is an intensive water-consuming industry that requires a sustainable and integrated water management strategy to reduce reliance on freshwater consumption. This study aims to develop a rigorous analytical tool based on water footprint principles and water pinch analysis techniques that can be used to manage and optimise water consumption. By performing thorough water audits, the water consumption footprint (the sum of blue and green water footprints) and the theoretical water pollution footprint (grey water footprint) were quantified. The total water consumption footprint of a brick is determined as 2.02 L, of which blue water is identified as 1.71 L (84.8%) and green water as 0.31 L (15.2%). The theoretical grey water footprint of a brick was found to be 1.3 L, a value that would have been higher if in-situ wastewater treatment had not been operated before effluent discharge. In order to reduce the water footprint of a brick, water pinch analysis techniques were applied for the brick-manufacturing processes. Two water recovery schemes were explored, i.e. direct re-use/recycle and water regeneration. For the former, water targeting was first carried out using the material recovery pinch diagram. Next, an algebraic technique was utilised for the targeting of water regeneration, where an interception unit is used to partially purify the water sources for further re-use/recycle. The network that fulfils the water flow rate targets was then designed using the nearest neighbour algorithm. The calculation indicates that direct re-use/recycle scheme reduces with the standard water consumption footprint reduced only by 15.6%. Water regeneration scheme, on the other hand improved the current value (which relies on an unsystematic water regeneration scheme) by 56.4%. The analysis clearly shows that the water consumption footprint of a brick is improved when the brick-manufacturing industry operates sustainable water management strategies. This study, a first of its kind, demonstrates that integration of water pinch analysis coupled with water footprint concepts, provides a robust and effective tool for the manufacturing industries that aim for sustainable water consumption.
This research is focused on the effect of temperature on the growth of active biofilms on polypropylene (PP) filter media in aerobic fixed biofilm reactors (FBR) for wastewater treatment.
High?throughput sequencing was used to explore the composition and diversity of the microbial community of 14?days old (starting phase) biofilms grown at 10, 20 and 30°C. Members of the classes Proteobacteria, Bacteroidetes, and Firmicutes were predominant in all the biofilm samples retrieved from PP?FBRs. A total of 108 genera of bacteria were identified, with some of them present in all three reactors, including Trichococcus, Zoogloea, Aeromonas, Acidovorax, and Malikias, among others. Besides these shared populations, certain genera were abundantlyfound in individual biofilm samples, like Brevundimonas (17.1%), Chitinimonas (10.3%) and Roseateles (39.3%), at 10, 20, and 30°C, respectively. The metabolic capabilities of active microbial communities in PP?FBRs were estimated by assessing the changes in different variables (BOD, DO, and pH) in the influent and effluent during operation. A note worthy BOD removal (66.6%) was shown by PP?FBRs operating at 30°C, as compared to 20°C (28.3%) and 10°C (28.8%),consistent with the DO levels recorded in the effluents, highest at 30°C (70.5%), and decreasing with the declining temperatures. Substantial wastewater treatment efficiencies were observed in the reactors at 30°C, attributable to the higher relative and diversity of microbial biofilms.
The development of physiologically active biofilms in PP at all prevailing temperatures strongly suggests that the material is suitable to be employed in FBRs for wastewater treatment at different operational temperatures.
Sadr Seyed M.K., Saroj Devendra, Mierzwa Jose Carlos, McGrane Scott J., Skouteris George, Farmani Raziyeh, Kazos Xenofon, Aumeier Benedikt, Kouchaki Samaneh, Ouki Sabeha K. (2018) A multi expert decision support tool for the evaluation of advanced
wastewater treatment trains: A novel approach to improve urban
sustainability,Environmental Science and Policy 90 pp. 1-10
Wastewater Treatment (WWT) for water reuse applications has been accepted as a strategic solution in improving
water supplies across the globe; however, there are still various challenges that should be overcome.
Selection of practical solutions is then required whilst considering technical, environmental, socio-cultural, and
financial factors. In this study, a multi expert decision support tool that considers a variety of evaluation criteria
is proposed to provide a ranking system for competing advanced WWT technologies in terms of their performance.
Two scenarios of water reuse in the contexts of Brazil and Greece are defined, and evaluation is undertaken
based on opinions of water reuse experts. The results prove that the tool would successfully facilitate
rigorous and methodical analysis in evaluation of WWT technologies for water reuse applications with potential
for use under various sets of evaluation criteria, WWT technologies and contexts.
The aim of this research is to evaluate the potential of low energy wastewater treatment processes to meet UK performance requirements, with respect to an increasingly strict regulatory framework
This research proposes the implementation of double filtration trickling filters (TF) operating in series without the requirement for intermediate settlement. Performance data is analysed and presented to demonstrate how a 50-80% biological offload of organic carbon (BOD) using a primary plastic media TF can enhance nitrification of existing conventional TFs. This configuration is capable of providing 97.4%, ammoniacal nitrogen (NH4-N) removal with effluent concentrations as low as 1.2mg/L.
Process performance data from 120 TF wastewater treatment works (WWTW) are analysed in order to evaluate the relative nitrification performance of TF WWTWs, both with and without aerated tertiary nitrifying processes. Multivariate regression analysis whilst considering flow, temperature and infiltration determines that tertiary nitrification contributes to a significantly higher risk of NH4-N consent being exceeded during colder winter periods. This directly challenges the current strategy of adopting tertiary processes for enhancing nitrification on TF WWTWs.
A decentralised facultative aerated lagoon (FAL) system with novel mixing and point source aeration is investigated and evaluated to determine its suitability for offloading existing WWTWs. Computational fluid dynamics (CFD) modelling describes the systems complex hydrodynamics and is validated with an experimental tracer study. Overall, this study showed that low energy mixing is capable of preventing hydraulic short circuiting and thermal stratification, which are notorious for reduced performance in traditional waste stabilisation pond variants.
Phosphorus (P) is an essential non-substitutable nutrient for all living organisms, but it is also a dwindling non-renewable resource. Approximately two-thirds of the world?s supply of phosphate rock is located in China, Morocco, and the USA. Phosphate rock is included in the EU list of ?critical raw materials? and is ranked 20th in an index of commodity price volatility. P recovery from waste water can help alleviate reliance on imported phosphate and reduce vulnerability to fluctuating prices. This project explored the options for P recovery from wastes produced across Thames Water?s waste water treatment plants (WWTPs), the main foci being sludge dewatering liquors and incineration/pyrolysis residues.
The research focussed specifically on the Slough WWTP and the operation of a newly installed Ostara system for recovery of P as struvite from dewatering liquors. The Ostara process is designed to operate with centrate PO4-P concentrations above 100 mg/l; to obtain these concentrations chemical coagulant dosing in the enhanced biological nutrient removal process must be reduced. Centrate monitoring following this change showed that Fe concentrations must measure consistently below 1.5 mg/l for PO4-P concentrations to remain steadily above 100mg/l. Following these changes onsite, operational savings and revenue can be produced onsite. Significant operational and maintenance savings totalling to £113K can be made in the first year of operation of the P recovery system in Slough WWTP. Sale of P rich struvite fertiliser produces annual revenue of £20K. Moving beyond the local benefits of P recovery, national benefits of P recovery were quantified. In a national context, a total of 28±1 kt P/year can be recovered from all WWTP waste streams, reducing P fertiliser imports by 36±1%. P recovery from WWTP influent and incinerated sewage sludge ash would reduce P losses to water bodies by 22±2%.
Sewage sludge may be incinerated, producing incinerated sewage sludge ash (ISSA), or alternatively pyrolysed to produce sewage sludge char (PSSC). The possibility of recovering P from these residual solids was also investigated. PSSC samples contained significantly more nitrogen and lower heavy metal concentrations than ISSA samples due to the process conditions. The % P extractions from both ISSA and PSSC plateaus at 0.6M and 0.8M H2SO4 acid concentrations, respectively, due to the formation of gypsum on the particles, so that further increase in acid concentrations does not increase P recovery.
The knowledge gained through this research has been used to improve the understanding and efficiency of the P recovery system at Slough WWTP. The information learned about pyrolysis residues will be used by Thames Water to develop a novel P recovery process from PSSC. Combined, these findings can impact the industry by creating incentives and inform policies regarding P recovery.
Current research is based on an innovative approach of the fabrication of encapsulated sustainable, green, phytogenic magnetic nanoparticles (PMNPs), to inhibit the generation of secondary pollutants (Iron/Feo) during water treatment applications. These novel bio-magnetic membrane capsules (BMMCs) were prepared using two-step titration gel crosslink method, with polyvinyl alcohol and sodium alginate matrix as the model encapsulating materials to eliminate potentially toxic metals (Pb2+ and Cd2+) from water. The development of BMMCs was characterized by FTIR, XRD, XPS, SEM, VSM, TGA and EDX techniques. The effects of various operating parameters, adsorbent dose, contact time, solution pH, temperature, initial concentration of metals cations and co-existing ions were studied. The hysteresis loops have illustrated an excellent super-paramagnetic nature, demonstrating the smooth encapsulation of PMNPs without losing their magnetic properties. The maximum monolayer adsorptive capacities estimated at pH 6.5 by the Langmuir isotherm model were 548 and 610.67/mg/g for Pb2+ and Cd2+, respectively. The novel BMMCs did not only control oxidation of PMNPs but also sustained the adsorptive removal over a wide range of pH (3?8), and the electrostatic interaction and ion-exchange were the core adsorption mechanisms. The BMMCs could easily be regenerated using 25% HNO3 as an eluent for successful usage in seven repeated cycles. Therefore, the BMMCs as a material can be used as an excellent sorbent or composite material to remove toxic metals Pb2+ and Cd2+, showing strong potential for improving water and wastewater treatment technologies.
Novel bio-magnetic membrane capsules (BMMCs) were prepared by a simple two-step titration-gel cross-linking method using a polyvinyl alcohol (PVA) and sodium alginate (SA) matrix to control the disintegration of phytogenic magnetic nanoparticles (PMNPs) in an aqueous environment, and their performance was investigated for adsorbing cationic malachite green (MG) dye from water. The prepared BMMCs were characterized by FTIR, powder XRD, SEM, EDX, XPS, VSM and TGA techniques. The findings revealed that the hysteresis loops had an excellent superparamagnetic nature with saturation magnetization values of 11.02 emu g?1. The prepared BMMCs not only controlled the oxidation of PMNPs but also improved the adsorptive performance with respect to MG dye (500 mg g?1 at 298.15 K and pH 6.5) due to the presence of a large amount of hydrophilic functional groups (hydroxyl/?OH and carboxyl/?COOH) on/in the BMMCs. The smooth encapsulation of PMNPs into the PVA?SA matrix established additional hydrogen bonding among polymer molecular chains, with improved stability, and adsorptive performance was maintained over a wide range of pH values (3?12). Importantly, the prepared BMMCs were easily regenerated just by washing with water, and they could be re-utilized for up to four (4) consecutive treatment cycles without observing any apparent dissolution of iron/Fe0 or damage to the morphology. According to the mass balance approach, an estimated amount of 100 mL of treated effluent can be obtained from 160 mL of MG dye solution (25 mg L?1) just by employing a 0.02 g L?1 adsorbent dosage. Finally, a model of BMMCs based on zero-effluent discharge was also proposed for commercial or industrial applications. The prepared BMMCs are greatly needed for improving the water/wastewater treatment process and they can be utilized as an excellent adsorbent to remove cationic pollutants for various environmental applications.
Current industrial livestock production has one of the highest consumptions of water, producing up to ten times more polluted (biological oxygen demand, BOD) wastewaters compared to domestic sewage. Additionally, livestock production grows yearly leading to an increase in the generation of wastewater that varies considerably in terms of organic content and microbial population. Therefore, suitable wastewater treatment methods are required to ensure the wastewater quality meets EU regulations before discharge. In the present study, a combined lab scale activated sludge-filtration-ozonation system was used to treat a pre-treated abattoir wastewater. A 24-h hydraulic retention time and a 13-day solid retention time were used for the activated sludge process, followed by filtration (4?7 ¼m) and using ozone as tertiary treatment. Average reductions of 93% and 98% were achieved for chemical oxygen demand (COD) and BOD, respectively, obtaining final values of 128 mg/L COD and 12 mg/L BOD. The total suspended solids (TSS) average reduction reached 99% in the same system, reducing the final value down to 3 mg/L. Furthermore, 98% reduction in phosphorus (P) and a complete inactivation of total coliforms (TC) was obtained after 17 min of ozonation. For total viable counts (TVC), a drastic reduction was observed after 30 min of ozonation (6 log inactivation) at an injected ozone dose of 71 mg/L. The reduction percentages reported in this study are higher than those previously reported in the literature. Overall, the combined process was sufficient to meet discharge requirements without further treatment for the measured parameters (COD, BOD, TSS, P, TC and TVC).
The unrestricted discharge of domestic and industrial wastewaters along with agricultural runoff water into the environment as mixed-wastewater pose serious threat to freshwater resources in many countries. Mixed-wastewater pollution is a common phenomenon in the developing countries as the technologies to treat the individual waste streams at source are lacking due to high operational and maintenance costs. Therefore, the need to explore the potential of the suspended growth process which is a well-established process technology for biological wastewater treatment is the focus of this paper. Different wastewater constituents: representing domestic, pharmaceutical, textile, petroleum, and agricultural runoff were synthesized as a representative of mixed-wastewater and treated in two semi-continuous bioreactors (R1 & R2) operated at constant operating conditions, namely MLSS (mg/L): 4640-R1, 4440-R2, SRT: 21-d, HRT: 48?72?h, and uncontrolled pH. The system attained stable condition in day 97, with average COD, BOD and TSS reduction as 84.5%, 86.2%, and 72.2% for R1; and 85.1%, 87.9%, and 75.1% for R2, respectively. Phosphate removal on average was by 74.3% in R1 and 76.6% in R2, while average nitrification achieved in systems 1 and 2 were 56.8% and 54.7%, respectively. The biological treatment system has shown potential for improving the quality of mixed-wastewater to the state where reuse may be considered and tertiary treatment can be employed to polish the effluent quality.
In this study, a pilot-scale trickling biofilter (TBF) using pebbles and gravels media was evaluated for the treatment of domestic wastewater. The TBF system was installed in an open environment at residential area of Quaid-i-Azam University, Islamabad, Pakistan, and was operated at three different recirculation flow rates (Q), i.e. 0.04, 0.072 and 0.1?m³/day and under three different HRTs, i.e. 48, 72 and 96?h. It was observed that the efficiency of pilot-scale TBF system in terms of pathogens removal was significant, i.e. at flow rates of 0.04, 0.072 and 0.1?m³/day, an average reduction of 39.8?62.5% (p = 0.007), 35.9?48.6% (p = 0.01) and 25.8?57.3% (p = 0.009) respectively were attained in CFU/mL under different HRTs. Moreover, it has been observed that due to high void spaces up to 30%, pebbles and gravels filter media in co-ordination allowing good microbial growth and increased the diversity of bacterial species. Furthermore, it also facilitate the removal of different pollutant indicators, i.e. chemical oxygen demand (COD) (74.2?80.5%), total dissolved solids (TDS) (60.3?69.5%), electric conductivity (EC) (62.8?68.6%) and phosphates (PO4) (45.3?60.3%). A significant reduction in total nitrogen (TN) (59?63.3%) was observed at flow rates of 0.04 and 0.072?m³/day (p = 0.005). The experimental data of this research study will be helpful for further modification in the TBF system using different filter media in association and selecting optimal HRTs and flow rates in future study to get maximum efficiency of TBF system while treating domestic wastewater.
Graphene oxide (GO), as an emerging material, exhibits extraordinary performance in terms of water treatment. Adsorption is a process that is influenced by multiple factors and is difficult to simulate by traditional statistical models. Artificial neural networks (ANNs) can establish highly accurate nonlinear functional relationships between multiple variables; hence, we constructed a three-layered ANN model to predict the removal performance of Cu(II) metal ions by the prepared GO. In the present research work, GO was prepared and characterized by FT-IR spectroscopy, SEM, and XRD analysis techniques. In ANN modeling, the Levenberg?Marquardt learning algorithm (LMA) was applied by comparing 13 different back-propagation (BP) learning algorithms. The network structure and parameters were optimized according to various error indicators between the predicted and experimental data. The hidden layer neurons were set to be 12, and optimal network learning rate was 0.08. Contour and 3-D diagrams were used to illustrate the interactions of different influencing factors on the adsorption efficiency. Based on the results of batch adsorption experiments combined with the optimization of influencing factors by ANN, the optimum pH, initial Cu(II) ion concentration and temperature were anticipated to be 5.5, 15 mg L?1 and 318 K, respectively. Moreover, the adsorption experiments reached equilibrium at about 120 min. Combined with sensitivity analysis, the degree of influence of each factor could be ranked as: pH > initial concentration > temperature > contact time.
Due to the increasing freshwater deterioration and demand for irrigation, there is pressing need to reclaim and reuse wastewater for agricultural operations. While this practice is gaining significant traction in developed world, it is quite rare in most developing countries with inadequate or no functional sewerage facilities and treatment systems at both municipal and industrial levels occasioned by high investment and operational costs. Consequently, wastewaters generated are in complex heterogenous mix of industrial, domestic, municipal and agricultural runoff wastewater. Biological technologies which utilize the expertise of microorganisms are considered robust, efficient and economically attractive for treatment of wide range of wastewaters and they have high suitability in developing countries. This work therefore assessed the potential of suspended growth biological process (SGBP) for reclamation and reuse of mixed wastewater composed a mixture of domestic effluent, pharmaceutical, textile, petroleum discharges and agricultural runoff for irrigation of edible crops (lettuce and beets) with plants phenological parameters as measuring indicators. The germination and phenological characteristics of crops were studied in a hydroponic unit under four irrigation regimes: tap water as control, mixed wastewater, SGBP treated wastewater, and tap water mixed with nutrient solution as upper control, for a duration of 45-d. The results proved that the SGBP treated wastewater had no negative impact on germination responses of the seed crops. However, residual recalcitrant compounds caused early stunted growth in plant root systems with resultant limited access to nutrients. Consequently, plant vegetative growth and phenological development as well as chlorophyll production were reduced. In comparison to nutrients supplemented solution, nutrients deficiency and imbalance in treated wastewater contributed to the poor development in irrigated plants. The outcomes of seed germination and plant growth experiments show a positive indication for reuse of mixed wastewater in agriculture. However, there is need for further research to explore the long-term benefits and limitations of reusing such treated wastewater.
In this work, the removal of Methylene Blue dye from the synthetic textile effluent has been
investigated using a hybrid system (photocatalysis and nanofiltration). The Commercial ZnO
powder was used as a catalyst in the photocatalytic operation. Response surface methodology
(RSM) was employed to optimize the various operating parameters such as pH, catalyst
loading and time duration and this optimization has enhanced the decolorization efficiencies.
The results were compared and contrasted with the individual as well as the combined
systems at optimized conditions. The results indicate that the photocatalysis process alone has
resulted in 33% of dye decolorization and 26.5% of total organic carbon (TOC) removal,
while the individual ceramic nanoflitration system has yielded 43% of decolorization and
35.03% TOC removal. About 94% of the dye were decolorized, and 70% of TOC was
removed in 94.23 minutes of operation by the hybrid system at optimized initial operating
This work reports the influence of ultrasound alone and combined with ozone for the treatment of real abattoir wastewater. Three different frequencies were studied (44, 300 and 1000 kHz) at an applied power of 40 W. The injected ozone dose was fixed at 71 mg/L and the treatment time varied from 1 to 60 min. Using ultrasound alone, 300 kHz was the only frequency showing a reduction in chemical oxygen demand (COD, 18% reduction) and biological oxygen demand (BOD, 50% reduction), while no diminution in microbial content was measured for any of the frequencies studied. Combining ultrasound with ozone, on the contrary, led to a significant decrease in COD (44%) and BOD (78%) removal for the three frequencies under study. A complete inactivation of total coliforms (TC) was obtained, as well as a final value of 99 CFU/mL in total viable counts (TVC, 5 log reduction). That is, the ozonation-sonication combined system was the only treatment method (compared to sonication and ozonation alone) reaching direct discharge limits, as well as meeting drinking water standards for microbial disinfection (TC and TVC).
The present investigation is focused on development of aerobic biofilm on tire derived rubber
(TDR) media and then evaluation of such system for bioremediation of Methylene blue (MB)
dye for 9 weeks. After 9 weeks of operation, the COD, BOD, ammonia and color values have
been declined by 89.2, 98.3, 99.61 and 99.81% respectively, While SEM-EDX results showed
a variance in weight percent of various elements in TDR without biofilm i.e. raw TDR media,
as well as in the 1st and 9th week samples. Moreover, fine and strong peaks were observed in
both the MB simulated wastewater and 9th week TDR samples at 1190, 1300, 1400, 1450, 1500
and 1618 cm-1 respectively by Raman Spectroscopic analysis. Further, FTIR analysis was
performed for the MB simulated wastewater, and absorbance peaks ranging from 1591 to 1363
cm-1 and 3410 cm-1 were observed in all the samples with different intensities. To assess the
biodeterioration of the TDR media, ATR was performed for the raw, 1st, 2nd and 9th week TDR
media samples and in the raw TDR, two important bands, 842 and 2962 cm-1 were noticed
representing ?CH=CH and ?CH3. A clear variation of bands and peak intensities were observed
in different support media samples. The results indicate that TDR media is a resilient,
chemically resistant material and could be employed for the biofilm growth for biological
treatment of textile dye wastewater.
The current work explores the treatment of dye wastewater using the combination of photocatalysis and ceramic nanofiltration process. Commercial ceramic membrane and titanium dioxide (TiO2) photocatalyst were used in this study to investigate the removal of Brilliant Green (BG) dye from the synthetic dye wastewater solution. The effect of various operating parameters on dye decolorization and total organic carbon removal were investigated. The operating parameters (pH, catalyst loading and time duration) were optimized using an experimental design model namely Response Surface Methodology (RSM). The use of experimental design by RSM resulted in the improvement of dye decolorization at optimum conditions. In addition to these operating parameters, the trend of initial dye concentration and the influence of catalyst loading on permeate flux was also studied. Around 99% of decolorization was obtained by the hybrid system at 500 mg L? 1 of dye concentration, 1 g L? 1 of TiO2 dosage, pH of 4.2 and 90 min. The integrated system i.e. photocatalytic reactor with nanofiltration membrane has shown complete removal of BG dye compared to individual systems. From the present study, it can be concluded that this integrated system is one of the efficient methods for dye treatment.
The utilization of dyes in textile industries
has enormously increased in recent years and has
created several environmental problems. Currently,
several methods are in practice to treat wastewaters.
Effective and efficient treatment techniques before the
discharge of used water in the environment are the
need of the hour. This short review covers the research
and recent developments in advanced wastewater
treatment techniques such as nanophotocatalysis,
ceramic nanofiltration membranes, and biofilms. The
primary intent of this review article is to contribute the
ready-made references for the active researchers and
scientists working in the field of wastewater treatment.
This review has mainly focused on advanced physicochemical
and biological techniques for the treatment
of textile dye wastewaters. Further, the influence of
various operating factors on the treatment, advantages,
and disadvantages of various techniques was also
discussed. The recently developed materials for
wastewater treatment are also summarized based on
the latest available literature.