Chemical Oxygen Demand Levels Research Articles

The Influence of Aloe Vera Biocoagulant and Mixing Time in Reducing Biological Oxygen Demand, Chemical Oxygen Demand and Total Suspended Solids Levels

Aloe vera is a plant with complex composition of carbohydrates, sugars, and mucilage, enabling it to bind particles in water and serve as a coagulant in the coagulation-flocculation process. This study aims to assess the impact of varying doses and rapid stirring times on the reduction of biochemical oxygen demand (BOD), chemical oxygen demand (COD), and total suspended solids (TSS) levels in liquid waste from pharmaceutical companies. The research involves two factors: (1) aloe vera concentration at three levels (20 mL/L, 40 mL/L, and 60 mL/L); (2) fast mixing time at three levels (20 minutes, 40 minutes, and 60 minutes), with each treatment repeated thrice. Levels of BOD, COD and TSS were measured post-treatment using a jar test tool. The results of the analysis showed that the optimal efficacy of the aloe vera coagulant occurred at a concentration of 40 mL/L for 40 minutes. At this optimal condition, the effectiveness of the aloe vera coagulant in reducing BOD, COD and TSS levels was 72.3%, 78.5%, and 65.3%, respectively. This indicates that the aloe vera coagulant can be effectively utilized in the treatment of pharmaceutical industrial wastewater to reduce BOD, COD and TSS levels

Low Strength Wastewater Treatment Using a Combined Biological Aerated Filter/Anammox Process

To achieve the in situ capacity expansion of the post-denitrification biological aerated filter (BAF-DN), the integration of BAF with the anammox process (BAF/AX) was proposed. With the objective of maximizing retaining ammonia nitrogen, the operational optimization of BAF was achieved by two distinct strategies. The treatment performance of BAF demonstrated that the removal efficiencies of chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N) was 66.3~67.3% and 4~12%, respectively, under conditions of low aeration intensity (0.4 m3·m−2·h−1) or a shortened empty bed residence time (EBRT) of 30 min. Residual NH4+-N in the BAF effluent served as the ammonia substrate for the subsequent anammox process, which was successfully launched by using ceramic particles and sponges as carriers. Notably, the sponge carrier facilitated a shorter start-up period of 41 to 44 days. Furthermore, the sponge-based anammox reactor exhibited a superior NH4+-N removal capacity (≥85.7%), under operations of a shorter EBRT of 40 min, low influent NH4+-N concentrations (≤30 mg/L), and COD levels of ≤67 mg/L. In addition, a comprehensive evaluation of the BAF/AX process was conducted, which considered performance, cost-effectiveness, and engineering feasibility. The performance results illustrated that the effluent quality met the standard well (with a COD level of ≤ 50 mg/L, and a TN of ≤3.1~10.5 mg/L). Following a comparison against the low aeration intensity operation, it was recommended to operate BAF at a low EBRT within the BAF/AX process. Consequently, the treated volume was double the volume of the standalone BAF-DN, synchronously achieving low costs (0.413 yuan/m3).

Assessment on the Effect of Rapid Urbanization on Groundwater Quality of Mirpur Area, Dhaka City, Bangladesh

Dhaka’s population is increasing day by day as more people are migrating towards Dhaka city for improving their level of living and for availing the cities amenities. Hence, this is creating pressure on the overall water quality of Dhaka city. The work intended to assess the groundwater standard in Mirpur area of Dhaka City, Bangladesh by analyzing eight (08) different physicochemical water quality parameters. In December 2023, six (06) separate water samples were taken throughout the dry season from six (06) sites across the area. The results showed that all sites had pH levels between 7.18 to 7.50, which is within acceptable ranges for drinking water quality and indicates neutral to slightly alkaline conditions. Total dissolved solids (TDS) continued to be far below safety limits (210–250 ppm), indicating that the water's mineral content was quite low. Electrical conductivity (EC) measurements fell within acceptable ranges (290-350 μS/cm), indicating suitable groundwater quality. Dissolved oxygen (DO) levels varied (3.7-9.3 mg/L), with some sites exhibiting satisfactory oxygenation while others raised concerns about potential water quality issues. Total hardness (TH) levels (330-900 mg/L) exceeded recommended limits (200-500 mg/L) at all sites, suggesting potential issues with water quality. However, chemical oxygen demand (COD) levels were minimal or zero (0-3 mg/L), indicating minimal organic pollution. Iron concentrations were generally low (0-0.05 mg/L). Total chlorine (TC) concentrations varied (0- 0.03 mg/L) across sites. In summary, the study emphasizes how crucial it is to continuously monitor and regulate the quality of groundwater in order to guarantee the sustainability and safety of water resources in the Mirpur region.

Enhanced lipid production of Auxenochlorella pyrenoidosa using biochar-pretreated tobacco industry wastewater

Tobacco industry wastewater, containing high levels of nicotine, organic carbon, dyes, and other pollutants, presents significant environmental and health challenges. This study evaluates the combined application of wood-derived biochar and microalgal biorefineries for effective treatment of this wastewater. A 3 % biochar dosage was determined to be optimal, achieving complete nicotine removal, enhancing wastewater transmittance from 12.29 % to 88.8 %, and reducing chemical oxygen demand (COD) levels by 87.7 % to 1757.3 mg/L, creating conditions favorable for the growth of Auxenochlorella pyrenoidosa. The pretreatment preserved key nutrients, such as sugars, total nitrogen (TN), and total phosphorus (TP), which supported enhanced microalgal photosynthesis and led to significant increases in biomass and lipid accumulation, particularly in unsaturated fatty acids. This shift in lipid composition contributed to a significant reduction in the cold filter plugging point value, improving the suitability of microalgae-derived biodiesel for use in cold climates. Transcriptomic analysis revealed upregulation of pathways involved in photosynthesis, carbon fixation, and fatty acid biosynthesis, while downregulation of the tricarboxylic acid (TCA) cycle minimized acetyl-CoA consumption, further promoting lipid synthesis. This integrated approach not only effectively detoxifies tobacco industry wastewater but also converts it into valuable biofuels, offering a promising and sustainable strategy for waste management and biofuel production.

Influence of Organic Loading Rates on the Treatment Performance of Membrane Bioreactors Treating Saline Industrial Wastewater

This study investigated the efficacy of membrane bioreactor (MBR) technology in treating saline industrial wastewater, focusing on the impact of the organic loading rate (OLR) and the food-to-microorganism (F/M) ratio on treatment performance. This research utilized saline industrial wastewater from Al-Hasa, which had salinity levels ranging from 5000 to 6900 mg/L. It explored treatment processes at varying Chemical Oxygen Demand (COD) concentrations of 800, 1400, and 2000 mg/L, corresponding to an OLR of 0.80 ± 0.05, 1.41 ± 0.07, and 1.98 ± 0.12 g COD/L, respectively. The average F/M ratios used were 0.20, 0.36, and 0.50 g COD/g MLSS·d, maintaining a constant Sludge Residence Time (SRT) of 12 days, a hydraulic retention time (HRT) of 24 h (hrs.), and a flux of 10 L/m2·h. The MBR system demonstrated high COD removal efficiencies, averaging 95.7 ± 1.6%, 95.5 ± 0.4%, and 96.1 ± 0.3%, alongside Biochemical Oxygen Demand (BOD) removal rates of 98.3 ± 0.2%, 99.8 ± 0.1%, and 98.5 ± 0.1%, respectively. However, an increased OLR led to elevated residual COD and BOD levels in the treated effluent, with COD concentrations reaching 34.2 ± 12.8, 63.3 ± 5.9, and 76.5 ± 5.4 mg/L, respectively. This study also reveals a significant decline in ammonia and Total Kjeldahl Nitrogen (TKN) removal efficiencies as OLR increases, dropping from 96.1 ± 0.5% to 80.2 ± 0.9% for ammonia and from 83.8 ± 3.4% to 65.8 ± 2.3% for TKN. Furthermore, higher OLRs significantly contribute to membrane fouling and elevate the transmembrane pressure (TMP), indicating a direct correlation between OLRs and operational challenges in MBR systems. The findings suggest that for optimal performance within the Saudi disposal limits for industrial wastewater, the MBR system should operate at an F/M ratio of ≤0.33 g COD/g of Mixed Liquor Suspended Solid (MLSS)·d. This study underscores the critical role of the OLR and F/M ratio in treating saline industrial wastewater using MBR technology, providing valuable insights for enhancing treatment efficiency and compliance with environmental standards.

NOB suppression by organic pollutants in mainstream single-stage partial nitrification/anammox (PN/A) process: Experimental evidence and modelling investigation

Effectively and stably suppressing nitrite oxidizing bacteria (NOB) under mainstream conditions is difficult for the wide application of the partial nitrification/anammox (PN/A) process. In this work, a continuous-flow single-stage PN/A reactor experiencing nitrate accumulation was restored by increasing the influent chemical oxygen demand (COD) concentrations. Experimental results showed that the total nitrogen removal efficiency quickly increased from 70 ± 2.54 % to 84 ± 1.21 % while effluent nitrate concentrations dropped from 30 ± 4.07 mg N/L to 10 ± 3.18 mg N/L following increasing the influent COD concentrations. A modified and calibrated mathematical model was employed to quantify the nitrogen conversion process and microorganism distributions under various influent COD levels. The detailed nitrogen metabolism network was calculated by labeling the source and sink of nitrite and nitrate. Simulation results revealed that influent COD suppressed NOB activity and enhanced anammox bacteria (AMX) activity in a short-term dynamic state while leading to the elimination of NOB and enrichment of the AMX under long-term pseudo-steady state. N-metabolism simulation results indicated that more nitrite (from 46.62 mg N/L to 55.05 mg N/L) was diverted to AMX with the assistance of heterotrophic bacteria (HET). NOB was outcompeted due to the dual pressure of competing with HET and AMX for oxygen and nitrite, respectively. Microbial analysis solidly supported these findings, showing that Candidatus_kuenenia, Thauera and Denitratisoma were enriched, while the relative abundance of Nitrospira decreased after COD addition. These findings demonstrate the potential of using organic pollutants to suppress and eliminate NOB, thereby enhancing the stability and efficiency of mainstream PN/A reactors.

Innovative waste activated sludge pre-treatment using a raceway pond Reactor: Integration of Low-Temperature and solar radiation

A novel pre-treatment, using a raceway pond reactor (RPR), combining the use of thermal and solar effects, was applied to enhance anaerobic digestion (AD) of waste activated sludge (WAS) from an urban wastewater treatment plant. Thermal pre-treatment at 25, 50, 60 and 70 °C was carried out for 5 h with (under distinct values of UV radiant power) and without solar radiation and varying WAS depth in the RPR (5 or 7 cm). Higher temperatures (60 and 70 °C) and longer treatment times (3 to 5 h) resulted in increased disintegration of bacterial cells. The WAS pre-treatment significantly (p-value ≤ 0.001) boosted soluble chemical oxygen demand (SCOD) levels, achieving a disintegration degree of 19.7 % at 70 °C with solar radiation (7.2 kJUV L-1WAS), which corresponds to a 15-fold increase of SCOD, compared to the baseline at 25 °C without radiation. Moreover, at the highest temperature (70 °C), there was a significant SCOD increase (p-value ≤ 0.05) of approximately 400 mgO2 L-1 in the presence of solar radiation. This synergetic effect between temperature and solar radiation caused cell damage, membrane rupture, and release of cellular content, shifting extracellular polymeric substances from tightly bound to loosely bound and soluble fractions, consequently improving methane production. Methane production increased by 131 % compared to the control (25 °C) under 70 °C and after 7.2 kJUV L-1WAS, indicating a positive impact on WAS hydrolysis. The technology adopted in this work fosters methane production predominantly using renewable solar energy without chemical residues. This is the first report on RPR for WAS pre-treatment, combining mild temperature and solar radiation.

Effectiveness of Eco Enzymes in Reducing Chemical Parameters of Tofu Factory Liquid Waste in Klumutan Village, Saradan District

The tofu industry generates substantial liquid waste that poses environmental challenges due to its high chemical oxygen demand (COD), total suspended solids (TSS), and pH levels. This study aimed to determine the effectiveness of Eco Enzymes in reducing these chemical parameters in the tofu industry waste in Klumutan Village, Saradan District. Utilizing a Quasi-Experimental method, the research employed purposive sampling of liquid waste from tofu production. The findings revealed that the application of Ecoenzyme at doses of 5%, 10%, and 15%, with detention times of 10, 15, and 20 days, significantly reduced COD, TSS, and pH levels. The results showed that both the dosage and detention time had a substantial impact on the effectiveness of Ecoenzyme in treating the waste. The implications of this study suggest that Eco Enzymes can be an effective, eco-friendly solution for improving wastewater management in the tofu industry, thereby contributing to environmental sustainability.

Effectiveness of natural herbs on sewage and treated municipal wastewater: A comparative study

Improperly handled sewage is the main cause of water pollution. Nearly 62% of wastewater in urban India remains untreated or partially treated, which further gets disposed of in the natural water bodies. The usual treatment methods include the activated sludge process, oxidation ponds, aerated lagoons, and trickling filters. These methods need spacious areas, a lot of energy and time, which drives up the cost of the treatment. The expense of the treatment process can be decreased by using natural coagulants. The indigenous medical system uses plants, which are abundant in secondary metabolites, to treat a variety of illnesses. The purpose of this study was to comprehend how these indigenous plants can be utilized for treating sewage water, as a low-cost accessible method that can be used by citizens to get access to clean drinking water. Material & Methods: A quick and low-cost method was created to investigate the efficacy of Moringa oleifera (Moringa), Ocimum sanctum (Tulsi), and Azadirachta indica (Neem) in the treatment of sewage water. This herb treated water was then compared to municipal treated water from the Ghatkopar Wastewater treatment facility, managed by the Municipal Corporation of Greater Mumbai (MCGM), Mumbai, India. All the herb-based components were bought from regional markets, and water samples from a lagoon found in the nearby Ghatkopar lagoon in Mumbai. Results: When compared to the lagoon-treated water, the efficacy of the sewage water treated with herbs was higher or comparable. Coliform and copper levels decreased considerably in the treated sample. Herb-treated samples showed a reduction in the Chemical Oxygen Demand (COD) levels as compared to the treated water. Conclusion: When combined, the herbs had a significant impact on lowering the COD, Copper, and coliform levels, making the native plants a valuable source for the treatment of sewage water.

Mitigating environmental pollution from tofu industry wastewater: Case of Suyanto Tofu Factory, Mojokerto

Background: This research investigates the impact of tofu industry wastewater on water environments at Suyanto Tofu Factory, Mojokerto. The tofu industry generates liquid waste containing high pH, Total Suspended Solids (TSS), Biochemical Oxygen Demand (BOD), and Chemical Oxygen Demand (COD), potentially polluting local rivers. Despite Suyanto Tofu Factory having wastewater treatment facilities, these are currently non-functional, underscoring the urgent need for designing new wastewater treatment installations. Methods: In this context, the study aims to determine the volume of wastewater produced, analyze the levels of BOD, COD, TSS, and pH in the wastewater, and design sustainable wastewater treatment facilities using a Constructed Wetland system. Findings: This method is expected to minimize the environmental impact of tofu wastewater, protect surrounding aquatic ecosystems, and comply with environmental regulations. By proposing sustainable solutions, the research aims to enhance awareness and management of wastewater in the tofu industry, offering technology solutions appropriate to local conditions. Conclusion: In conclusion, implementing effective and sustainable wastewater treatment installations is crucial to safeguard water quality and river ecosystems around Suyanto Tofu Factory. Novelty/Originality of this Study: By proposing a Constructed Wetland system for tofu industry wastewater treatment, this research introduces an innovative, sustainable solution tailored to local conditions, potentially revolutionizing waste management practices in small-scale food industries.

Assessment of temporal and spatial variations of water quality parameters in the Zarafshan River basin

AbstractRiver ecosystems in Central Asia face significant stress from environmental changes and pollution. This study assesses temporal and spatial variations in water quality parameters within the Zarafshan River Basin using retrospective data and field measurements. Water quality indicators, including electrical conductivity (EC), total suspended solids (TSS), ammonium nitrogen (N‐NH4), nitrite nitrogen (N‐NO2), nitrate nitrogen (N‐NO3), temperature (T), chemical oxygen demand (COD), dissolved oxygen (DO), and discharge, were analyzed using the Pearson's correlation coefficient and ANOVA, with the Mann–Kendall (MK) test detecting trends over time. Obtained results indicate significant seasonal effects with elevated TSS during summer, increasing sediment load and changing aquatic habitats. The strong inverse correlation (–0.89) between DO and N‐NH4 signifies ecological challenges particularly in low DO concentrations during summer (3.25 mg L–1). Long‐term analysis identifies Navoiazot chemical factory as a major pollution hotspot. Spatial analyses based on extended sampling have revealed the Siab and Dargom canals and Samarkand City as major pollution sources of elevated N‐NO2 and COD, respectively. Trends at various gauging stations (MK‐test) show increasing EC (τ = 0.72) and N‐NH4 (τ = 0.46) levels, with decreasing TSS, N‐NO3, T, and COD levels over time. Recommendations include targeted measures to reduce pollution at the Navoiazot factory and downstream, introducing sustainable agriculture practices, increasing public awareness for environmental conservation, and improving urban wastewater treatment to meet water quality requirements for different users.

On-line measurement of COD and nitrate in water against stochastic background interference based on ultraviolet–visible spectroscopy and physics-informed multi-task learning

Traditional ultraviolet–visible spectroscopic quantitative analytical methods face challenges in simultaneous and long-term accurate measurement of chemical oxygen demand (COD) and nitrate due to spectral overlap and the interference from stochastic background caused by turbidity and chromaticity in water. Addressing these limitations, a compact dual optical path spectrum detection sensor is introduced, and a novel ultraviolet–visible spectroscopic quantitative analysis model based on physics-informed multi-task learning (PI-MTL) is designed. Incorporating a physics-informed block, the PI-MTL model integrates pre-existing physical knowledge for enhanced feature extraction specific to each task. A multi-task loss wrapper strategy is also employed, facilitating comprehensive loss evaluation and adaptation to stochastic backgrounds. This novel approach significantly outperforms conventional models in COD and nitrate measurement under stochastic background interference, achieving impressive prediction R2 values of 0.941 for COD and 0.9575 for nitrate, while reducing root mean squared error (RMSE) by 60.89 % for COD and 77.3 % for nitrate in comparison to the conventional chemometric model partial least squares regression (PLSR), and by 30.59 % and 65.96 %, respectively, in comparison to a benchmark convolutional neural network (CNN) model. The promising results emphasize its potential as a spectroscopic instrument designed for online multi-parameter water quality monitoring against stochastic background interference, enabling long-term accurate measurement of COD and nitrate levels.

Potential of Vermifiltration Technique to Reduce Chemical Oxygen Demand, Biological Oxygen Demand, and Total Suspended Solid of Farm Dairy Effluent in Developing Countries: Case of Indonesian Farm Dairy Industry

Farm dairy effluent (FDE) contains high level of Chemical Oxygen Demand (COD), Biological Oxygen Demand (BOD), and Total Suspended Solids (TSS) which caused river and groundwater pollution. To reduce those parameters, vermifiltration technique was utilized for dairy effluent treatment. It also could reduce greenhouse gasses (GHG) emissions, removing organic and excessive nutrients without odor and recovering manure nutrients in the treated dairy effluent and vermicompost. The objective of this study is to evaluate the potential of Vermifiltration in reducing COD, BOD and TSS of the FDE. Samples of wastewater were collected from dairy farm industry from 3,542 of total cow populations located in Bandung regency, Indonesia. The sample characteristics of COD, BOD, TSS, pH, NH3-N, organic carbon, and macro nutrients (total N, P2O5, and K2O) were measured before and after vermifiltration treatment. Vermifiltration treatment will produce two types of products i.e.: tea water and vermicompost. The result showed that Vermifilter removed the COD, BOD, and TSS of 93%, 95%, and 93% respectively. The organic carbon NH3-N, and total macro nutrients generally decreased after treated by Vermifilter (2.01 to 0.0001% of organic carbon, 718 to 3.75 mg L-1 of NH3-N, 0.2 to 0.02% of total N, 0.19 to 004% P2O5, 0.57 to 0.18% of K2O); however, the pH was not significantly changing (from 8.13 to become 8.05). Vermicompost produced by vermifiltration beds by earthworms consumes sewage solids and excreting them in the vermicast which produces high macronutrients (2.4% of total N, 5.5% of P2O5, and 0.75% of K2O), and organic carbon (15.6%), hence beneficial for soil fertilizer. Vermifilter effectively degrades the organic matter in the dairy effluent. Derivatives produced by the Vermifiltration process, namely tea water and Vermicompost, can be used as substitutes for irrigation materials and organic fertilizers on agricultural land, and act as soil conditioners to improve soil properties.

STATISTICAL ASSESSMENT OF WATER QUALITY PARAMETERS FOR POLLUTION SOURCE IDENTIFICATION IN NOYYAL RIVER, COIMBATORE, TAMILNADU

<p>This study aimed to determine the extent of the water quality decrease in the Noyyal River in Tamilnadu by analyzing the seasonal change of water's physicochemical properties, identifying possible sources of pollution, and grouping the monitoring months based on shared characteristics. The measurements were taken during four different seasons. Forty percent of the water quality indices, including turbidity, DO concentration, EC, Cl concentration, TA, and COD in all seasons, were found to be outside the acceptable limits recommended by various agencies, according to the analytical data. A 95% confidence interval's worth of statistical analysis revealed that 52% of the contrasts differed significantly. Four factors accounted for 93.44% of the variation overall, according to the factor analysis, which showed the best fit between the parameters. The significant pollution loading, primarily attributed to toxicological chemicals and industrial discharge, was reflected in Total Dissolved Solids, Biochemical Oxygen Demand, Chemical Oxygen Demand, Electrical Conductivity, Turbidity, Dissolved Oxygen, and Chloride levels. Cluster analysis revealed a seasonal variation in surface water quality, indicating contamination from rainfall or other sources. Nevertheless, seasons did impact the levels of various physicochemical characteristics, with winter recording the highest pollution values. The Noyyal River's seasonal temperature change and increased rainfall were the causes of this self-refining tendency, which goes winter < summer < pre-winter < rainy season.</p>

The treatment of high concentration wastewater in the natural gas processing industry.

The operation of the Cansolv tail gas treatment device in natural gas plants generates acidic and alkaline wastewater from the venturi unit and amine purification unit (APU), respectively. The APU wastewater is complex in composition and contains hard-to-degrade organic matter, which can adversely impact the normal functioning of the water treatment system. This study assesses the efficacy of three ozone-based advanced oxidation processes (ozone (O3), ozone/hydrogen peroxide (O3/H2O2), and ozone/Fenton (O3/Fenton)) for treating Cansolv wastewater, with chemical oxygen demand (COD) and total organic carbon (TOC) serving as indicators of organic degradation. The findings demonstrate that all three processes effectively eliminate coloration and reducible sulfur, with O3/Fenton exhibiting superior performance in removing organic substances. The treated wastewater has a clarified light-yellow appearance with residual COD levels at 43 mg L-1. Under the optimum Fenton oxidation conditions (initial pH 5, H2O2 dosage 97.8 mmol L-1, FeSO4·7H2O dosage 550 mg L-1), average TOC and COD removal rates reached 50% and 97%, respectively. After a treatment duration of 60 minutes, the wastewater demonstrated an enhanced membrane-specific flux, confirming the effectiveness of the O3/Fenton oxidation process in mitigating membrane fouling while ensuring the stable operation of the wastewater treatment system.

Developing a novel continuous-flow cascade photocatalytic system for effective sulfamethoxazole elimination from hospital wastewater

In this study, we introduce a novel continuous-flow cascade photocatalytic system specifically designed to efficiently remove sulfamethoxazole (SMX) from hospital wastewater, addressing the critical need for sustainable pharmaceutical wastewater treatment. The system utilizes a carbon sponge-based TiO2 photocatalyst synthesized via a hydrothermal process under mild conditions. The system’s design incorporates multiple stages in a cascade configuration, meticulously optimized to enhance photocatalytic efficacy, thereby significantly improving the rate of SMX elimination while minimizing energy consumption. The study encompasses comprehensive characterization of the photocatalyst, including matching its absorption spectrum to the emission spectrum of the light source, as well as fine-tuning key operational parameters such as catalyst quantity, flow rates, and cascade configuration. Real-world application tests confirm the system’s efficiency, achieving approximately 80 % SMX removal efficiency alongside a notable reduction in Chemical Oxygen Demand (COD) levels. Furthermore, the system’s energy efficiency, as reflected by an Electrical Energy per Order (EEO) value of 7.53 kWh/m3, highlights its potential for scalable and sustainable wastewater treatment solutions. This study not only contributes significantly to the field of environmental catalysis but also represents a significant advancement in sustainable environmental management, offering a promising solution to the urgent challenge of pharmaceutical pollution in water sources.

Green marvel: Harnessing spinach leaves' power for enhanced photodegradation of various effluents with biogenic ZnO nanoparticles

This study investigates the use of ZnO NPs (Zinc oxide nanoparticles) derived from spinach leaf extracts in a sustainable photocatalytic technology to enhance the decomposition of hazardous effluents from refineries and paper mills. The biosynthesized ZnO NPs were characterized through X-ray diffraction (XRD), UV-Vis spectroscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD analysis reveals that ZnO NPs possess a hexagonal wurtzite structure, exhibiting a preferred arrangement of (101) planes. The synthesized ZnO NPs have a spherical shape, as seen in the SEM images. TEM analysis detected the size of the ZnO NPs to be between 35 and 40 nm. The results indicate that ZnO NPs produced via biosynthesis have photocatalytic activity in efficiently decomposing the organic chemicals found in gasoline refining effluent when exposed to light. At a pH of 8, the ZnO NPs exhibited the highest rate of degradation for toluene (84.26 %) and xylene (90.36 %) after being exposed to simulated sunlight for 240 min. In the context of the photocatalytic treatment of paper mill effluents, it has been shown that the subsequent cycles resulted in a reduction in chemical oxygen demand (COD) levels of 81.24 %, 74.14 %, 68.92 %, 60.24 %, and 53.82 %, respectively.

Effect of Initial pH for Polluted River Water Treatment Via Pilot Scale Membrane Photocatalytic Reactor (MPR)

Conventional technologies such as physical, chemical, and biological treatment have low efficiency, a tendency towards fouling, and use high energy consumption, respectively.Coagulation-flocculation base treatment, nearly 40-60%, during thelatest technologies as an advanced organic process (AOP) with Fenton-reagents, nearly 80-85% in dissolved organic compound (DOC) reduction, respectively. It proves that emerging technology and new green technology are needed. Therefore, the objective of this study is (i) to treat polluted rivers using pilot-scale MPRs with different initial pH of 5, 7 and 9 and adsorption-desorption time contact for 20, 30 and 40 minutes using 0.05 g/L ZnO-Kaolin loading, 225W light intensity, pressured one bargand 30 minutes’ photocatalytic reaction time. (ii) analysing the physico-chemical quality of the water before and after the treatment as turbidity, ammoniacal nitrogen (𝑁𝑁𝑁𝑁3𝑁𝑁) biochemical oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), and pH levels using the HACH method with 90.89%, 84.93%, 83.19%, 99.38%, 19.47% and 0.63% removal efficiency respectively. (iii) Analyzing the kinetic reaction between the pseudo-first and pseudo-second order models using turbidity data. In conducting the experiment, the sample of polluted river water was taken at Sungai Sembrong, Batu Pahat. From the result obtained, when pH five and time adsorption-desorption time contact for 30 minutes was the optimum condition for degrading and removing the organic matter. Moreover, it obeys the pseudo-second-order model, which relates to the chemisorption processbetween the ZnO-Kaolin and organic compounds. Overall, MPRs are claimed as a promising technology that is environment-friendly for wastewater treatment applications.

Biological treatment of N-methylpyrrolidone, cyclopentanone, and diethylene glycol monobutyl ether distilled residues and their effects on nitrogen removal in a full-scale wastewater treatment plant

Manufacturing processes in semiconductor and photonics industries involve the use of a significant amount of organic solvents. Recycle and reuse of these solvents produce distillate residues and require treatment before being discharged. This study aimed to evaluate the performance of the biological treatment system in a full-scale wastewater treatment plant that treats wastewater containing distillate residues from the recycling of electronic chemicals. Batch experiments were conducted to investigate the optimal operational conditions for the full-scale wastewater treatment plant. To achieve good nitrogen removal efficiency with effluent ammonia and nitrate concentrations below 20 mg N/L and 50 mg N/L, respectively, it was suggested to control the ammonia concentration and pH of the influent below 500 mg N/L and 8.0, respectively. In addition, the biodegradability of N-methylpyrrolidone, diethylene glycol monobutyl ether, and cyclopentanone distillate residues from the electronic chemicals manufacturing process were evaluated under aerobic, anoxic, and anaerobic conditions. N-methylpyrrolidone and cyclopentanone distillate residues were suggested to be treated under anoxic condition. However, substrate inhibition occurred when using cyclopentanone distillate residue as a carbon source with chemical oxygen demand (COD) levels higher than 866 mg/L and nitrate levels higher than 415 mg N/L. Under aerobic condition, the COD from both N-methylpyrrolidone and cyclopentanone distillate residues could be easily degraded. Nevertheless, a negative effect on nitrification was observed, with a prolonged lag time for ammonia oxidation as the initial COD concentration increased. The specific ammonia oxidation rate and nitrate production rate decreased under high COD concentration contributed by N-methylpyrrolidone and cyclopentanone distillate residues. Furthermore, the biodegradability of diethylene glycol monobutyl ether distillate residue was found to be low under aerobic, anoxic, and anaerobic conditions. With respect to the abundance of nitrogen removal microorganisms in the wastewater treatment plant, results showed that Comammox may have an advantage over ammonia oxidizing bacteria under high pH conditions. In addition, Comammox may have higher resistance to environmental changes. Dominance of Comammox over ammonia oxidizing bacteria under high ammonia condition was first reported in this study.

Integrated A/O-MBR–NF process for treating high COD content wastewater from traditional Chinese medicine

Traditional Chinese medicine (TCM) wastewater poses a significant environmental challenge due to its high chemical oxygen demand (COD) and complex components. This study demonstrates a highly effective treatment approach for complex TCM wastewater using a combination of hydrolysis-acidification (HA) pre-treatment, anaerobic-aerobic membrane bioreactor (A/O-MBR), and nanofiltration (NF). Pudilan Xiaoyan Oral Liquid (PDL) wastewater, characterized by high COD (around 5500 mg/L) and baicalin content, served as the model feedstock. The A/O-MBR demonstrated removal rates of 23.6 mg COD g biomass−1 h−1 and 1.0 mg NH3-N g biomass−1 h−1. The combined A/O-MBR-NF process achieved exceptional COD removal exceeding 99 %, significantly reducing the wastewater's environmental impact. Importantly, the treated effluent exhibited no biological toxicity in zebrafish acute toxicity tests, demonstrating the effectiveness of this approach in detoxifying PDL wastewater. Analysis of the A/O-MBR's bacterial community further elucidates the treatment mechanism. This study indicates that MBR treatment for complex TCM wastewater is feasible and holds promising industrial prospects, offering a fresh perspective on the treatment of TCM wastewater with high COD levels.