Anaerobic Treatment Process Research Articles

Electric stimulation mitigated the mixed microplastic inhibition to anaerobic digestion during wastewater treatment

The presence of mixed microplastics (MPs) in anaerobic wastewater treatment processes has been shown to impede fermentation performance by suppressing microbial activity. Microbial electrosynthesis (MES), with its extensive potential, offers a promising solution for refractory substances management and methane recovery, achieved through the enhancement of microbial metabolism and interspecies electron transfer. This study, therefore, delves into the functional impacts and the microbial response to MES in the remediation of wastewater contaminated with mixed-MPs. Results indicated that mixed-MPs could inhibit methane production (−52.38%) and substance removal (−26.59%), and MES could effectively mitigate this inhibitory effect (−22.86%, −19.01%). Concurrently, MES also boosts enzymatic activities pivotal for electron transfer, such as cytochrome c and nicotinamide adenine dinucleotide (NADH), as well as those linked to energy metabolism like adenosine triphosphate (ATP). Furthermore, MES bolsters microbial resistance to mixed-MPs, as evidenced by an increase in extracellular polymeric substances (EPS), albeit with a minor rise in reactive oxygen species (ROS) production and lactate dehydrogenase (LDH) release. Correspondingly, electric stimulation promoted the enrichment of functional microorganisms associated with fermentation, acetate production, electrogenesis, and methanogenesis, and stimulated elevated expression levels of genes related to methane metabolism. Notably, the Methanothrix-mediated acetoclastic pathway emerges as the predominant methanogenic route, succeeded by the Methanobacterium-driven hydrogenotrophic pathway. Lastly, the study underscores the supportive role of applied voltage and carriers in energy metabolism and substance transport, which are associated with methanogenesis. Overall, MES demonstrates efficacy in mitigating the biotoxicity induced by mixed-MPs exposure and in enhancing anaerobic wastewater treatment and methane recovery.

Performance evaluation of ICX reactor in treatment of paper mill wastewater: a case study in South Vietnam.

This study evaluates the performance of the Internal Circulation eXperience (ICX) reactor in treating high-strength paper mill wastewater in the south of Vietnam. The ICX reactor effectively managed organic concentrations (sCOD) of up to 11,800 mg/L. Results indicate a volumetric loading rate (VLR) of 26.8 kg/m3 × day, achieving processing efficiency exceeding 81% while consistently maintaining volatile fatty acids (VFA) below 300 mg/L. The study employed Monod and Stover-Kincannon kinetic modeling, revealing dynamic parameters including Ks = 56.81 kg/m3, Y = 0.121 kgVSS/kgsCOD, Kd = 0.0242 1/day, μmax = 0.372 1/day, Umax = 151 kg/m3 × day, and KB = 175.92 kg/m3 × day, underscoring the ICX reactor's superior efficiency compared to alternative technologies. Notably, the reactor's heightened sensitivity to VFA levels necessitates influent concentrations below 1,400 mg/L for effective sludge treatment. Furthermore, the influence of calcium on treatment efficiency requires post-treatment alkalinity maintenance below 19 meq/L to stabilize MLVSS/MLSS concentration. Biogas production ranged from 0.6 to 0.7 Nm3 biogas/kg sCOD; however, calcium impact diminished this ratio, reducing overall treatment efficiency and biogas production. The study contributes valuable insights into anaerobic treatment processes for complex industrial wastewaters, emphasizing the significance of controlling VFA, calcium, and alkalinity for optimal system performance.

Using the kriging method based on cross-validation stepwise variable selection to optimize anaerobic wastewater treatment process

In this study, process parameters for wastewater treatment are optimised in order to improve the efficiency of energy recovery from wastewater treatment. In order to identify process parameters that have a significant impact on carbon recovery, we propose a stepwise forward variable selection method based on K-fold cross kriging to validate the loss ER.The results show that for complex wastewater treatment systems, the cross-validated kriging-based stepwise variable selection method can predict carbon recovery quickly and accurately. Finally, this paper combines the kriging prediction model with the PSO optimisation strategy to determine the optimal set points of process parameters with the objective of maximising carbon recovery.

Investigation of organic content and microbial characteristics distribution at the pretreatment units for wastewater treatment plant sustainable upgrading

It is necessary and significant to acquire the influent characteristics in the whole pretreatment units of the activated sludge process in wastewater treatment plants (WWTPs) for the sustainable upgrading. In this work, we drawn the samples and continuously investigated all the structure units of the pretreatment section in a typical wastewater treatment plant including the anaerobic and aerobiotic treatment processes. We monitored the routine environmental parameters in the water, including dissolved oxygen (DO), pH, and suspended solids (SS). At the same time, we investigated the concentration distribution patterns of chemical oxygen demand (COD) and biochemical oxygen demand (BOD5) and found that the degradation of organic matter in the sewage continued in the pretreatment section. And the remarkable decreasing tendency of organic pollution concentration was confirmed along the flow direction in the pretreatment section, suggesting a modest depletion effect on influent organic matter of the pretreatment process. Moreover, to further validate the degradation process of organic compounds in the preprocessing procedure, analysis and detection were conducted on the types of organic compounds and the microbial community structures in the water samples collected at various sampling points through three-dimensional fluorescent spectroscopy and high-throughput sequencing, respectively. Conclusively, the detailed and accurate influent characteristics can support the scientific basis for the WWTP sustainable operation, management, and upgrading, especially for that with the low C/N ratio influent.

Study on the Environmental Impact and Benefits of Incorporating Humus Composites in Anaerobic Co-Digestion Treatment.

This study evaluated the environmental impact and overall benefits of incorporating humus composites in the anaerobic co-digestion of kitchen waste and residual sludge. The life cycle assessment method was used to quantitatively analyze the environmental impact of the entire anaerobic co-digestion treatment process of waste, including garbage collection, transportation, and final product utilization. Moreover, the comprehensive assessment of the environmental impact, energy-saving and emission-reduction abilities, and economic cost of using humus composites in the anaerobic co-digestion treatment process was conducted using a benefit analysis method. The results showed that the anaerobic co-digestion of kitchen waste and residual sludge significantly contributed to the mitigation of global warming potential (GWP), reaching -19.76 kgCO2-eq, but had the least impact on the mitigation of acidification potential (AP), reaching -0.10 kgSO2-eq. In addition, the addition of humus composites significantly increased the production of biogas. At a concentration of 5 g/L, the biogas yield of the anaerobic co-digestion process was 70.76 m3, which increased by 50.62% compared with the blank group. This amount of biogas replaces ~50.52 kg of standard coal, reducing CO2 emissions by 13.74 kg compared with burning the same amount of standard coal. Therefore, the anaerobic co-digestion treatment of kitchen waste and residual sludge brings considerable environmental benefits.

Deciphering the core bacterial community structure and function and their response to environmental factors in activated sludge from pharmaceutical wastewater treatment plants

Pharmaceutical wastewater is recognized for its heightened concentrations of organic pollutants, and biological treatment stands out as an effective technology to remove these organic pollution. Therefore, a comprehensive exploration of core bacterial community compositions, functions, and their responses to environmental factors in pharmaceutical wastewater treatment plants (PWWTPs) is important for understanding the removal mechanism of these organic pollutants. This study comprehensively investigated 36 activated sludge (AS) samples from 15 PWWTPs in China. The results revealed that Proteobacteria (45.41%) was the dominant phylum in AS samples, followed by Bacteroidetes (19.54%) and Chloroflexi (4.13%). While the dominant genera were similar in both aerobic and anaerobic treatment processes, their relative abundances exhibited significant variations. Genera like HA73, Kosmotoga, and Desulfovibrio were more abundant during anaerobic treatment, while Rhodoplanes, Bdellovibrio, and Hyphomicrobium dominated during aerobic treatment. 13 and 10 core operational taxonomic units (OTUs) were identified in aerobic and anaerobic sludge, respectively. Further analysis revealed that core OTUs belonging to genera Kosmotoga, Desulfovibrio, Thauera, Hyphomicrobium, and Chelativorans, were associated with key functions, including sulfur metabolism, methane metabolism, amino acid metabolism, carbohydrate metabolism, toluene degradation, and nitrogen metabolism. Furthermore, this study highlighted the crucial roles of environmental factors, such as COD, NH4+-N, SO42−, and TP, in shaping both the structure and core functions of bacterial communities within AS of PWWTPs. Notably, these factors indirectly affect functional attributes by modulating the bacterial community composition and structure in pharmaceutical wastewater. These findings provide valuable insights for optimizing the efficiency of biochemical treatment processes in PWWTPs.

Bioponic systems with biochar: Insights into nutrient recovery, heavy metal reduction, and microbial interactions in digestate-based bioponics

Bioponics is a nutrient-recovery technology that transforms nutrient-rich organic waste into plant biomass/bioproducts. Integrating biochar with digestate from anaerobic wastewater treatment process can improve resource recovery while mitigating heavy metal contamination. The overarching goal of this study was to investigate the application of biochar in digestate-based bioponics, focusing on its efficacy in nutrient recovery and heavy metal removal, while also exploring the microbial community dynamics. In this study, biochar was applied at 50 % w/w with 500 g dry weight of digestate during two 28-day crop cycles (uncontrolled pH and pH 5.5) using white stem pak choi (Brassica rapa var. chinensis) as a model crop. The results showed that the digestate provided sufficient phosphorus and nitrogen, supporting plant growth. Biochar amendment improved plant yield and phosphate solubilization and reduced nitrogen loss, especially at the pH 5.5. Furthermore, biochar reduced the heavy metal accumulation in plants, while concentrating these metals in the residual sludge. However, owing to potential non-carcinogenic and carcinogenic health risks, it is still not recommended to directly consume plants cultivated in digestate-based bioponic systems. Additionally, biochar amendment exhibited pronounced impact on the microbial community, promoting microbes responsible for nutrient solubilization and cycling (e.g., Tetrasphaera, Herpetosiphon, Hyphomicrobium, and Pseudorhodoplanes) and heavy metal stabilization (e.g., Leptolinea, Fonticella, Romboutsia, and Desulfurispora) in both the residual sludge and plants. Overall, the addition of biochar enhanced the microbial community and facilitated the metal stabilization and the cycling of nutrients within both residual sludge and root systems, thereby improving the overall efficiency of the bioponics.

Enzymatic Pretreatment of Slaughterhouse Wastewater: Application of Whole Lipolytic Cells of Rhizopus oryzae Produced from Residual Vegetable Oil

This study assessed the application of whole lipolytic cells in the pretreatment of slaughterhouse wastewater to reduce its lipid content. The fungal biomass of Rhizopus oryzae was evaluated in the hydrolysis of slaughterhouse wastewater containing high lipid concentrations, focusing on the biomass’s concentration and the effect of using an emulsifier and surfactant. The use of the whole-cells lipase of Rhizopus oryzae grown in a residual vegetable oil medium proved effective in the hydrolysis of slaughterhouse wastewater, generating concentrations of free fatty acids (FFA) ranging from 40.36 to 90.14 mM. The action of lipase in the hydrolysis of slaughterhouse residues indicated its effectiveness in pretreating lipid-rich liquid residues, potentially boosting the microbiota of this anaerobic treatment. The results showed that lipase activity without surfactant exhibited a similar performance to that of Triton X-100 in the hydrolysis of liquid residues. However, the combination of lipase and surfactant could represent a promising strategy to optimize free fatty acid production from slaughterhouse residues, strengthening anaerobic treatment processes and potentially enhancing the overall efficiency of waste management systems.

Research on the Application and Mechanisms of Electroactive Microorganisms in Toxicants Monitoring: A Review.

A biological treatment is the core process for removing organic pollutants from industrial wastewater. However, industrial wastewater often contains large amounts of toxic and harmful pollutants, which can inhibit the activity of microorganisms in a treatment system, precipitate the deterioration of effluent quality, and threaten water ecological security from time to time. In most of the existing anaerobic biological treatment processes, toxic effects on microorganisms are determined according to the amounts of end-products of the biochemical reactions, and the evaluation results are relatively lacking. When microorganisms contact toxic substances, changes in biological metabolic activity precede the accumulation of reaction products. As sensitive units, electroactive microorganisms can generate electrical signals, a change in which can directly reflect the toxicity level. The applications of electroactive microorganisms for the toxicity monitoring of wastewater are very promising. Further attention needs to be paid to considering the appropriate evaluation index, the influence of the environment on test results, mechanisms, and other aspects. Therefore, we reviewed the literature regarding the above aspects in order to provide a research foundation for the practical application of electroactive microorganisms in toxicant monitoring.

Insight into microbial adaptability in continuous flow anaerobic ammonium oxidation process for low-strength sewage treatment

Organic matter concentration is a critical factor influencing the adaptability of anaerobic ammonium oxidation (anammox) bacteria to low-strength sewage treatment. To address this challenge and achieve stable anammox activity, a micro-aeration partial nitrification-anammox process was developed for continuous-flow municipal sewage treatment. Under limited ammonium conditions, the effective utilization of organics in denitrification promoted the stable accumulation of nitrite and enhanced anammox activity. This, in turn, led to enhanced nitrogen removal efficiency, reaching approximately 87.7%. During the start-up phase, the protein content of extracellular polymeric substances (EPS) increased. This enhanced EPS intensified the inhibitory effect of denitrifying bacteria (DNB) on nitrite-oxidizing bacteria through competition for nitrite, thereby facilitating the proliferation of anammox bacteria (AnAOB). Additionally, several types of DNB capable of utilizing slowly biodegradable organics contributed to the adaptability of AnAOB. These findings provide valuable insights for ensuring efficient anammox performance and robust nitrogen removal in the treatment of low-strength sewage.

Biogas situation and development in Thai Swine Farm

The biogas technology in Thailand has been developed and adopted for many years, especially in the swine farm industry. The objectives of the biogas development are based on three main problems; i.e. (i) to reduce the appalling odor, (ii) to treat the wastewater, (iii) and to produce the biogas which is known as a renewable energy sources from the anaerobic digestion wastewater treatment processes. In this paper, the biogas situation including the technology development for swine farm in Thailand, which are mainly used the upflow anaerobic sludge blanket (UASB) bioreactor system, was discussed. From the results, we found that 11.6 million cubic meters of biogas per year would be produced under the government subsidization projects which gas then be used for various proposes; e.g. electricity generation, LPG or fuel oil substitution in boiler and heating system

Simulating Biogas Production Process from Palm Oil Mill Effluent for Power Generation

The rapid growth of the palm oil industry in Indonesia has made it the world's largest palm oil producer. However, this progress comes with a challenge as the industry generates Palm Oil Mill Effluent (POME), which poses an environmental threat if directly discharged into the environment. POME contains high concentrations of organic compounds that can be harnessed to produce energy in biogas through anaerobic treatment processes. This study aims to develop an efficient POME biogas production technique for large-scale power generation. The biogas production process with a capacity of 675.38 Kg/batch, 51,9 tonnes/year, and economic evaluation were simulated using SuperPro Designer v13.0. Biogas production from POME involves a series of stages employing anaerobic microorganisms for organic material decomposition, including hydrolysis, acidogenesis, acetogenesis, and methanogenesis. The simulation results indicate that the plant can produce biogas with a composition of 86.228% methane, 1.507% water, 0.059% hydrogen, 0.016% hydrogen sulfide, and 1.959% carbon dioxide within a batch time of 114 hours. The economic feasibility simulation resulted in a Net Present Value (NPV) of $553,000, Internal Return Rate (IRR) of 19.3%, and Payback Period (PBP) of 4.22 years. Those results confirm the viability of these projects.

Prediction of the effluent chemical oxygen demand and volatile fatty acids for anaerobic treatment based on different feature selections machine-learning methods from lab-scale to pilot-scale

The effluent chemical oxygen demand (COD) and volatile fatty acids (VFA) are important indicators for measuring wastewater anaerobic treatment systems. Through lab and pilot experiments on the anaerobic treatment process of high-salt wastewater, combined with different prediction requirements, the feature variables are classified. The effluent-COD and VFA prediction models of five different Machine-learning methods (i.e., back propagation neural network (BPNN), Genetic algorithm optimizes BPNN(GA-BP), support vector machine (SVM), Least squares support vector machine (LSSVM), and random forest (RF)) were established. The modeling results on different dataset (i.e., lab dataset, pilot dataset and mixed dataset) showed that the SVM and LSSVM methods based on statistical learning had the best model prediction performance in lab and pilot datasets, and the RF method performed well in mixed dataset. Furthermore, the genetic algorithm was adopted to optimize the RF model. After optimization of mixed dataset, the effluent-COD prediction (i.e., R2 = 0.966, RMSE/MAE are 61.227/48.584 mg/L) and VFA prediction (i.e., R2 = 0.639, RMSE/MAE are 26.838/21.831 mg/L) have been improved compared with the original RF model (i.e., R2 = 0.918, RMSE/MAE are 86.232/65.03 mg/L of effluent-COD, and R2 = 0.539, RMSE/MAE are 35.489/26.726 mg/L of VFA). This research can provide a reference for the prediction of the anaerobic treatment of actual large-scale industrial wastewater.

Rapid start-up strategy and microbial population evolution of anaerobic ammonia oxidation biofilm process for low-strength wastewater treatment

The implementation of the anaerobic ammonium oxidation (anammox) process in treating low-strength wastewater is limited by the difficulty in enriching anammox bacteria (AnAOB). Here, the first enrichment of AnAOB at a high nitrogen (N) loading rate (NLR) as a strategy was proposed to achieve the rapid start-up of the anammox biofilm process treating low-strength wastewater. The long-term stability of the anammox biofilm process after start-up operating at a low NLR of 0.2–0.4 kg N/(m3⋅d) was evaluated. Results showed that the N removal efficiency was up to 75 % under a low NLR of 0.2 kg N/(m3⋅d) condition. Low-strength organic matter promoted the metabolic coupling between partial denitrifying bacteria (PDB) and AnAOB. The genus Candidatus Brocadia as AnAOB (18 %-27 %) can coexist with Limnobacter (PDB, 9 %-12 %) for efficient N removal. This study offers a rapid start-up strategy of anammox biofilm process in treating low-strength wastewater.

Life Cycle Assessment of Three Manure Treatment Modes in Large-scale Pig Farm

With the rapid development of China's livestock breeding industry, it is very important to efficiently deal with the pollution caused by livestock and poultry manure. In this study, the life cycle resource consumption and pollutant emission inventory of a large-scale pig farm were analyzed by life cycle assessment (LCA). The environmental impact potentials of three different modes of livestock and poultry manure treatment were analyzed, including aerobic composting, anaerobic fermentation and black soldier fly larvae (BSFL) treatment. Results showed that the environmental loads of BSFL treatment and anaerobic fermentation were much smaller than those of aerobic composting in the life cycle process of pig manure treatment. The environmental impacts of aerobic composting process were in the order of environmental acidification, eutrophication, and global warming; while the environmental impacts of anaerobic fermentation treatment and BSFL treatment process were in the order of global warming, environmental acidification, and eutrophication. It is recommended to strengthen the emission of CO2 and NH3 in the pig manure treatment process to reduce their environmental impacts.

Variations in the dairy wastewater properties and bacterial diversity of each unit in membrane-enclosed anaerobic lagoon treatment process in Heilongjiang Province

In order to meet the land use requirements of the treated wastewater from high density polyethylene (HDPE) membrane-enclosed anaerobic lagoons, the physical and chemical properties of the wastewater in an HDPE membrane-enclosed anaerobic lagoon were measured. The total nitrogen content (TN) in wastewater treated in membrane-enclosed anaerobic lagoons is 3165 and 1510 mg/L in winter and summer respectively. The wastewater can be used as liquid organic fertilizer, partly replacing chemical fertilizer. The safety dosage of the wastewater was 21.48 t/ha for rice and 9.54 t/ha for corn, respectively. Meanwhile, the wastewater has the characteristics of high salt (conductivity>16.0 mS/cm) and high organic matter content (COD>16,900 mg/kg). Therefore, the potential negative effects of the wastewater on soil salinity and pH should be assessed. 16S rRNA was used to investigate the bacterial population structure and assess potential biological risks of land use of the wastewater. The wastewater from lagoon has the least and the most bacterial abundance in summer and winter, respectively. The bacterial diversity of wastewater samples from lagoon is the most. 21 and 24 phyla were detected in winter and summer samples respectively. Clostridium is the absolute dominant bacteria in the summer water samples and the absolute dominant bacteria is Trichococcus in winter water samples. Several animal and plant bacterial pathogens such as Campylobacter, Corynebacterium, Facklamia and Erysipelothrix can be detected in the wastewater samples. More than 70% of pathogenic bacteria such as Campylobacter, Facklamia, Erysipelothrix and Acholeplasma can be removed by lagoon in summer, but only about 99% of Corynebacterium is still in the lagoon (XYH). While more than 60% of Corynebacterium, Facklamia and Erysipelothrix are not removed in winter. So the biological risk of land use of anaerobic pond wastewater needs to be considered.

Feasibility of anaerobic ammonium oxidation process for treatment of pretreated printed circuit board wastewater

The treatment of pretreated printed circuit board (PCB) wastewater by anaerobic ammonium oxidation (anammox) process has been rarely reported. This study sought to investigate the performance of the anammox process during various phases of pretreated PCB wastewater treatment. The nitrogen removal efficiency (NRE) reached 90 ± 10% at a Cu2+ concentration of 2.5 mg·L-1, but declined to 22 ± 11% as the Cu2+ level increased to 10.3 mg·L-1. During phase III, there was a 38% increase in the relative abundance of Candidatus Kuenenia compared to phase I. By adjusting the substrate concentration and introducing synthetic wastewater into the reactor, the anammox performance was nearly restored to that of phase I. These findings underscore the potential of the anammox process for treating pretreated PCB wastewater and expanding its practical applications to industrial wastewater treatment.

Surfactant and antibiotic co-occurrence reshaped the acidogenic process for volatile fatty acids production during sludge anaerobic fermentation

The overuse of surfactants and antibiotics has led to their high concentration in waste activated sludge (WAS), and these exogenous pollutants have been shown to pose various influences on the subsequent anaerobic treatment process. Previous works have primarily concerned the impacts of individual pollutants on WAS anaerobic fermentation process. This work revealed the synergetic effects of sodium dodecyl benzene sulfonate (SDBS) and sulfadiazine (SDZ) co-occurrence in WAS on the biosynthesis of volatile fatty acids (VFAs). The addition of SDBS in the SDZ reactor significantly increased VFAs generation, and this increase was correlated with the concentration of SDZ. The VFAs production exhibited a 200.0–211.9 % and 5.9–20.4 % increase in comparison with the sole SDZ and SDBS reactor, respectively. The SDBS and SDZ co-occurrence facilitated the solubilization, hydrolysis, and acidification stages of WAS fermentation synchronously. SDBS was effectively to disintegrate the cemented structure of extracellular polymeric substances and meanwhile improve the SDZ solubilization, which increase the SDZ bioavailability as well as biotoxicity to the anaerobic species. Herein, the anaerobic consortia structure was evidently reshaped, and the keystone microbes Acetoanaerobium and Fususibacter, as well-tolerated hydrolytic-acidogenic bacteria, were greatly enriched. Furthermore, the functional microbial metabolic traits responsible for the substrate extracellular hydrolysis (e.g., glsA and MAN2C1), intracellular metabolism (e.g., ALDO and asdA), and fatty acid generation (e.g., aarC) were all upregulated in the SDBS/SDZ co-occurrence reactor.

Three-dimensional graphene aerogel mitigated the toxic impact of chloramphenicol wastewater on microorganisms in an EGSB reactor

Anaerobic treatment of chloramphenicol wastewater holds significant promise due to its potential for bioenergy generation. However, the high concentration of organic matter and residual toxic substances in the wastewater severely inhibit the activity of microorganisms. In this study, a three-dimensional graphene aerogel (GA), as a conductive material with high specific surface area (114.942 m2 g−1) and pore volume (0.352 cm3 g−1), was synthesized and its role in the efficiency and related mechanism for EGSB reactor to treat chloramphenicol wastewater was verified. The results indicated that synergy effects of GA for Chemical Oxygen Demand (COD) removal (increased by 8.17 %), chloramphenicol (CAP) removal (increased by 4.43 %) and methane production (increased by 70.29 %). Furthermore, GA increased the average particle size of anaerobic granular sludge (AGS) and promoted AGS to secrete more redox active substances. Microbial community analysis revealed that GA increased the relative abundance of functional bacteria and archaea, specifically Syntrophomonas, Geobacter, Methanothrix, and Methanolinea. These microbial species can participate in direct interspecific electron transfer (DIET). This research serves as a theoretical foundation for the application of GA in mitigating the toxic impact of refractory organic substances, such as antibiotics, on microorganisms during anaerobic treatment processes.

Integrated Method of Ozonation and Anaerobic Process for Treatment of Atrazine bearing Wastewater

The paper presents the treatment of atrazine-contaminated wastewater by ozonation followed by an anaerobic process using Upflow Anaerobic Sludge Blanket (UASB) reactor. The experiment was performed with 100 ppb synthetic solutions of atrazine prepared in ultra-pure water. The corresponding initial Chemical Oxygen Demand (COD) is 226 mg.L-1. The initial pH was adjusted to 9.5. The atrazine-bearing synthetic wastewater was ozonated with an ozone dose of 9.4mg/l for 40 minutes of optimum ozonation time, resulting in a 35% reduction in the initial concentration of atrazine. Along with atrazine reduction, there was a COD removal of 54.42%. Further, it was degraded with an anaerobic process, resulting in the final reduction in atrazine concentration of 81% and the corresponding removal in COD of 86.7%. The process of ozonation led to the mineralization of atrazine and enhancement in the biodegradability of the wastewater. Using ion chromatography, the ozonated wastewater sample was analyzed for ionic by-products before and after ozonation. The ion chromatography results showed the breaking of the atrazine compound and the formation of Cl-, NO3-, SO42-, and F- as intermediate products. Further, the BOD5/COD ratio increased, reflecting the increased biodegradability. This ozonated wastewater was treated in a UASB reactor where the pesticide was degraded to 19 ppb, and COs degraded to 30 mg.L-1. The overall removal of atrazine pesticide and COD were 81% and 86.7%, respectively, in the integrated system of ozonation followed by anaerobic degradation.