Removal Of Pollutants In Wastewater Research Articles

Pollutant Removal in Wastewater from Anaerobic Digesters by Water Lettuce (<i>Pistia stratiotes</i> L.) at Both Still-Water and Running-Water Stages

Pollutant Removal in Wastewater from Anaerobic Digesters by Water Lettuce (<i>Pistia stratiotes</i> L.) at Both Still-Water and Running-Water Stages

Development of a novel polydopamine-imprinted MOFs targeted for removal of refractory organic pollutants: Synergistic mechanisms of adsorption and degradation

In this study, a novel dopamine-imprinted MOFs (metal organic frameworks) was developed for the first time to achieve targeted degradation of refractory organic pollutants (ROPs) in advanced oxidation process. The targeted adsorption and degradation capacity of sulfamethoxazole (SMX) by molecularly imprinted catalyst (Fe-MOFs@MIP) was 3.17 times and 5.47 times that of Fe-MOFs, respectively. The results showed that the polydopamine (PDA) imprinted layer not only enhanced the targeted adsorption of SMX, but also improved the activity of the catalyst by promoting electron transfer. The physicochemical properties of Fe-MOFs@MIP were investigated. In situ Fourier transform infrared spectroscopy and molecular dynamics theory were used to investigate targeted adsorption mechanism. The active species were identified by quenching experiments and electron paramagnetic resonance (EPR). The reaction sites of SMX were predicted using density functional theory (DFT) and the possible degradation pathways of SMX were proposed. Finally, the targeted degradation mechanism of Fe-MOFs@MIP was elucidated. This study has a guiding significance for the deep removal of refractory organic pollutants in wastewater.

Synergistic CdS@CeO2 nanocomposites: Harnessing Z-scheme electron transfer for enhanced photocatalytic CO2 conversion and aqueous Cr(VI) reduction

The present work describes the fabrication of CdS-D@CeO2 Z-scheme heterojunctions as highly stable, efficient and recyclable photocatalysts for the visible light assisted reduction of CO2 to methanol as well as Cr(VI) to Cr(III). The bare CeO2 produced methanol with the rate of 111 μmolh−1g−1 that is much lower in comparison to CdS-D@CeO2 (501 μmolh−1g−1). In addition, the photocatalytic efficiency remained nearly same for three successive runs, indicating the higher stability and recycling ability of the heterojunctions CdS-D@CeO2. It was also observed that under direct sunlight irradiation, CdS-D@CeO2 efficiently reduced 100% Cr(VI) to Cr(III) in an aqueous medium in just 40 minutes. Moreover, >95% removal was maintained even after 5 catalytic cycles. Additionally, for mimicking real contaminated water samples, the influence of the foreign ions on Cr(VI) reduction was evaluated by using lake water sample and no adverse effects on the result were observed. Thus, this work showed a way to develop cost-effective, easily synthesized, durable and recyclable composite photocatalysts for CO2 utilization and proficient removal of waste water pollutants by employing the clean, green, and renewable solar energy.

UV/H2O2 produced degradation of 2,4-D and 4-CPA

2,4-dichlorophenoxyacetic (2,4-D) acid and 4-chlorophenoxyacetic acid (4-CPA), as widely utilized organochlorine pesticides, are normally detected in wastewater and atmosphere. Their harmfulness to the ecosystem cannot be ignored. UV/H2O2 is one of the most conventional advanced oxidation processes, which has remarkable advantages for the removal of refractory organic pollutants in wastewater. However, the reaction mechanisms and pathways of pollutants with reactive radicals are still unclear. In this study, the degradation efficacy and mechanisms during the photodegradation of 2,4-D and 4-CPA in UV/H2O2 processes were investigated by experiments and density functional theory calculations. The results showed that 2,4-D was more likely to be degraded by UV/H2O2 treatment than UV photolysis alone. In contrast, 4-CPA can be degraded effectively and rapidly under UV irradiation alone. By LC-MS analysis, the degradation products of 2,4-D and 4-CPA in the UV/H2O2 processes were identified and they were produced by hydroxylation and photolysis. Therefore, we speculated a competition mechanism presented between direct photolysis and indirect photolysis in the UV/H2O2 degradation of 2,4-D and 4-CPA. The OH-initiated reaction mechanisms of 2,4-D and 4-CPA in aqueous environments were investigated using quantum chemical methods SMD/M06–2X/6–311++G (3df, 2p)//SMD/M06–2X/6-311 + G (d,p). The pH dependence of the reaction mechanisms and rate constants in their degradation process induced by ·OH was also investigated. The calculation results showed that the ionic forms (2,4-D- and 4-CPA-) were more prone to react with ·OH in comparison to the corresponding molecular forms (2,4-D and 4-CPA). The total rate constants of 2,4-D and 4-CPA with OH increased with the pH from 1 to 10, and decreased with continued pH increase. The toxicities of 2,4-D, 4-CPA and their products were assessed by the QSAR-based toxicity evaluation software. The results showed that several products were more toxic than their parent compounds, such as 2,4-dichlorophenol, 3,5-dichlorocatechol, 4-chlorophenol and hydroquinone. This work can contribute to clarifying the environmental risks of 2,4-D and 4-CPA and offer a complete understanding for the photodegradation behavior of 2,4-D and 4-CPA in aqueous ecosystems.

Sunlight-mediated efficient remediation of organic pollutants from water by chitosan co-decorated nanocomposites of NiO loaded with WO3: Green synthesis, kinetics, and photoactivity

Azo dyes such as Tropaeolin OOO (TOOO) and Eriochrome black T (EBT) are used in various industrial and laboratory applications. However, their recalcitrant properties make them toxic chemicals and require efficient removal-strategy based on polymer decorated semiconductor nanocomposite. Herein, photodegradation of TOOO and EBT in water was investigated at different reaction parameters through NiO@WO3-chitosan synthesized by green procedure using A. indica. PXRD spectra peaks show semi-crystalline behaviour with spherical morphology and chitosan around metal oxide. In FT-IR, New spectral peaks observed at 1023 cm−1, 870 cm−1, and 540 cm−1 vibration indicated between Ni-O-W, Ni-N, and W-N confirmed effecting coupling. Both dyes (10 mg/L) were found completely colourless within 3 h under sunlight with pH of 7 at 20 mg of catalyst load. Difference in max degradation of 96 % and 92 %, respectively to TOOO and EBT dye credit to structure difference. 1st-order reaction kinetics following early Langmuir adsorption and degradation at optimum condition rate constant k (0.26–0.19-min−1) and half time t1/2(2.68––3.64 min−1). Efficiency of NiO@WO3-chitosan was maintained due to its fine morphology with elevated surface-area (75 m2g−1), large negative zeta potential (−29.5 mV), and lesser value of band distance (2.1 eV). Involvement of •OH, O2–• and holes in photocatalysis mechanism to break complex molecules of TOOO and EBT was revealed in Scavenger analysis. After degradation, small-safer metabolites were confirmed by LC-MS. Reusability up to 8th cycle of NiO@WO3-chitosan without photoactivity reduction makes it a cost-effective cum sustainable composite for industries and wastewater pollutants removal with good surface properties.

Green synthesis of metal nanoparticles from Codium macroalgae for wastewater pollutants removal by adsorption

AbstractAlgae have adsorption properties and reducing agents due to their rich content. In this study, palladium nanoparticles (Pd NP), platinum nanoparticles (Pt NP), and iron oxide nanoparticles (Fe3O4 NP) were prepared from Codium macroalgae using green synthesis. The structure of the synthesized nanoparticles was elucidated by X‐ray diffractometry, Fourier transforms infrared spectroscopy, Brunauer–Emmett–Teller analysis, transmission electron microscopy, ultraviolet‐visible spectroscopy and scanning electron microscopy‐energy dispersive X‐ray spectrometry and their use as nanoadsorbents for the removal of pollutants from aqueous media was investigated in detail. Naproxen (NPX), an anti‐inflammatory drug, and the dyes methylene blue (MB) and cresol red (CR) were selected as pollutants for this study. Batch adsorption experiments were conducted using both real wastewater obtained from the Organised Industrial Zone of Isparta Province and synthetic water samples prepared with tap water from Burdur Province and pure water. Under optimum adsorption conditions, Pd NP showed significant efficiency in the real wastewater sample, with an adsorption capacity of 37.19 and 50.03 mg g–1 for CR and NPX, respectively, within 150 min. In comparison, Pt NP showed an adsorption capacity of 40.01 mg g–1 for MB within the same timeframe. These findings indicate that while Pd NP showed the highest adsorption capacity for both CR and NPX, Pt NP showed the highest adsorption capacity for MB. The Langmuir model and the pseudo‐second‐order equation were more suitable to describe the adsorption behavior of CR, MB, and NPX. In addition, studies on the desorption and reusability of the nanoadsorbents were carried out under the same optimum experimental conditions.

Facile construction of a novel S-scheme Fe2TiO5/BiVO4 photocatalyst for efficient visible light-driven fenton-like degradation of ciprofloxacin

The rational design and fabrication of stable and efficient heterogeneous Fenton-like catalyst is of great significance for wastewater treatment, but is still fraught with obstacles. In this paper, a novel S-scheme Fe2TiO5/BiVO4 nano-heterojunction with high visible-light photocatalytic performance was synthesized by an in-situ growth method. The optimized Fe2TiO5 (20 wt%)/BiVO4 composite exhibited remarkable photocatalytic activity and rapid degradation ability towards CIP (50 mg/L) with the addition of H2O2 (20 mM), achieving a removal efficiency of 94.2 % within 90 mins. This performance is significantly superior to that of pure BiVO4 (43.8 %) or pure Fe2TiO5 (48.2 %). The S-scheme heterojunction formed between Fe2TiO5 and BiVO4 facilitates efficient charge separation, and preserves the powerful photogenerated electrons in CB of Fe2TiO5 and holes in the VB of BiVO4, contributing to the fast degradation of CIP. The synergistic effects of the S-scheme heterojunction and H2O2 activation account for the excellent performance of Fe2TiO5/BiVO4 photocatalyst. The prepared photocatalyst demonstrates remarkable efficiency, non-selectivity, exceptional stability, and adaptability to various environmental conditions. This study proposes a novel approach for designing and synthesizing photo-assisted Fenton-like S-scheme photocatalysts for efficient removal of organic pollutants in wastewater.

Biofilm formation monitoring using SEM in synthetic wastewater pollutant removal by combination of DAF and modified MBBR

Nowadays, moving bed biofilm reactors (MBBR) and dissolved air flotation (DAF) are frequently used in combination for the biological and physical treatments of synthetic oily wastes. The efficiency of the biocarriers utilized in MBBR is crucial since it has a big impact on the system's overall performance. A study was carried out utilizing a DAF-MBBR technique to treat synthetic oily wastewater in order to evaluate this. Two different kinds of biocarriers were used in this modified MBBR: polyethylene and plastic bottle caps. The result showed the DAF-MMBBRs process demonstrated excellent removal efficiencies for a range of parameters. Moreover, it seemed that DAF had higher COD, nitrite, nitrate, and turbidity removal efficiencies. For COD, the average removal efficiency was 39.62%; for oil and grease, it was 77.05%; and for ammonia, it was 39.71%. In the same way, MBBR1 is effective at eliminating phosphate, ammonia, TSS, and oil and grease. For COD, the average removal efficiency was 39.12%; for oil and grease, it was 94.10%; and for ammonia, it was 85.42%. The average removal efficiencies for COD, oil and grease, and ammonia in MMBBR2 were 38.76%, 84.95%, and 86.49%, respectively. Furthermore, Scanning electron microscopy (SEM) was used to assess the biofilm within the system. This revealed a well-developed biofilm layer on the interior surfaces of the biocarriers, improving the effectiveness of synthetic wastewater treatment. Excellent removal efficiencies were shown by the DAF-MBBR system for a range of parameters during a ten-day operational period.

Biomimetic ZrO2-modified seaweed residue with excellent fluorine/ bacteria removal and uranium extraction properties for wastewater purification

Exploring and developing promising biomass composite membranes for the water purification and waste resource utilization is of great significance. The modification of biomass has always been a focus of research in its resource utilization. In this study, we successfully prepare a functional composite membrane, activated graphene oxide/seaweed residue-zirconium dioxide (GOSRZ), with fluoride removal, uranium extraction, and antibacterial activity by biomimetic mineralization of zirconium dioxide nanoparticles (ZrO2 NPs) on seaweed residue (SR) grafted with oxidized graphene (GO). The GOSRZ membrane exhibits highly efficient and specific adsorption of fluoride. For the fluoride concentrations in the range of 100–400 mg/L in water, the removal efficiency can reach over 99 %, even in the presence of interfering ions. Satisfactory extraction rates are also achieved for uranium by the GOSRZ membrane. Additionally, the antibacterial performance studies show that this composite membrane efficiently removes Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). The high adsorption of F− and U(VI) to the composite membrane is ascribed to the ionic exchange and coordination interactions, and its antibacterial activity is caused by the destruction of bacterial cell structure. The sustainability of the biomass composite membranes is further evaluated using the Sustainability Footprint method. This study provides a simple preparation method of biomass composite membrane, expands the water purification treatment technology, and offers valuable guidance for the resource utilization of seaweed waste and the removal of pollutants in wastewater.

Applications of bismuth-based nanoparticles for the removal of pollutants in wastewater: a review

This review discusses the characteristics and synthesis methods of Bi-based NPs. It delves into the removal efficiency in wastewater, emphasizing traditional/emerging strategies to enhance the performance, mechanisms, toxicology, and challenges.

Recent Advances on Removal of Pharmaceuticals Pollutants in Wastewater using Metal Oxides and Carbonaceous Materials as Photocatalysts: A Review

Pharmaceuticals industry have played an important role in the developing medicines in improving health and quality of life in treating human and animals around the world. But they are also...

Photo-Catalytic Activity Improvement for Organic Pollutant Removal in Wastewater using Zinc Oxide Quantum Dots: An Experimental and Modeling Study

Photo-catalyst nanoparticles (NPs) find applications in many diverse fields, including environmental remediation, energy conversion, and organic synthesis. By optimizing the nanoparticle's composition, size, morphology, and surface properties, the photo-catalytic performance can be enhanced to develop more efficient and sustainable catalytic systems. This work aligns with this innovative approach and aims to improve the photo-catalytic degradation of Sulfamethoxazole (SMX) through the intensification of the photo-catalyst and the micro-reactor. ZnO-NPs were synthesized using the sol-gel method. Zinc Acetate (Z.A) and sodium hydroxide were used as precursor materials. The resulting ZnO-NPs were characterized for their structure and crystallinity using X-Ray Diffraction (XRD) and the photo-catalytic activity was assessed with a micro-structured polymer reactor. The degradation of SMX through photo-catalysis proceeds through several stages that involve coupled processes, such as the transportation of molecules and chemical reactions. To solve the mathematical equations governing the transport and photocatalytic reaction, COMSOL Multiphysics software was utilized. The characterization results demonstrate the excellent crystallinity and high purity of the synthesized ZnO-NPs, enabling the estimation of the average diameter of the NPs under different synthesis conditions. The grain growth is faster (3.5 hr) at higher temperatures (70, 80, and 90 °C), and slower (4 hr) at lower temperatures (50 and 60°C). The photo-catalytic degradation is significantly more efficient on 16 nm ZnO-NPs than 50 nm ZnO-NPs. At this size, the conversion rate reaches 96%, surpassing the performance of commercial ZnO-NPs, which only degrades 81% of SMX. The conversion rate obtained through simulation is slightly higher than that achieved in the experiments. However, this difference remains negligible, and overall, the model fits well with the experimental data. This validation of the chosen model confirms its reliability and accuracy.

Synthesis of MnOOH-hydroxyapatite nanowires for degradation of tetracycline

Antibiotics are commonly present in the natural environment and pose a threat to human health due to their resistance to degradation or recycling. Therefore, finding an effective catalyst for antibiotic treatment remains a challenge. In this study, a fibrous inorganic nanocomposite, MnOOH-hydroxyapatite nanowires (MnO-HApNWs), was successfully synthesized by in-situ solvothermal method, and applied for removal of antibiotics. Tetracycline (TC), a widely used antibiotic, could be rapidly degraded with removal rates being 87.6% within 5 min, and 93.6% within 60 min, respectively. Based on nano-structure characterization, influence of key parameters, measurement of active species and analysis of degradation intermediates, the mechanism and degradation pathways of catalyze degradation was investigated. The high specific surface area and pore size of MnO-HApNWs facilitated the adsorption of TC onto its surface followed by catalytic degradation through the generation of reactive oxygen species. The scavenger experiments revealed that active radicals, such as •OH and O2•－, played a crucial role in the degradation of TC. Furthermore, MnO-HApNWs demonstrated cyclic stability and universality with over 85.1% efficiency even after 8 cycles of recycling. In summary, the prepared novel fibrous inorganic nanocomposites materials (MnO-HApNWs) exhibit exceptional catalytic performance with promising prospects for application in wastewater pollutant removal.

Laboratory investigation of filtration indicators in a gravity filtration unit filled with nano-packing

Today, the lack of drinking water has caused severe crises in many countries. One of the ways to deal with water shortages is to treat wastewater. Petrochemical industries are among the factories that produce significant wastewater. These industries cause a lot of damage to the ecosystem. The use of nanomaterials can play a significant role in the removal of wastewater pollutants. The use of nano-packing in the filtration structure has not been investigated in previous literature. In this research, a gravity filtration unit was used to treat the outlet wastewater from the Fajr petrochemical desalination unit. This unit is filled with titanium dioxide nano-packings. The results of this research show that the turbidity of the effluent discharged from the gravity filtration bed is reduced by about 39 %. This research shows that nano-packing has a significant effect on reducing total dissolved solids and organic carbon. This study shows that the amount of total dissolved solids and organic carbon in treated wastewater is equal to 1 % and 17.1 %, respectively. This research shows that the use of a gravity filtration unit has a significant role in reducing petrochemical effluent pollutants.

Syntheses characterization, and photocatalytic property of an organic-inorganic compound obtained by bromine salt and the β-Mo8O26 anion

According to the structure/property characteristics of polyacids, the design and synthesis of new inorganic organic hybrid materials based on POMs is of great significance for the rapid and effective removal of pollutants in wastewater. In addition, many researchers have synthesized a large number of POMs-based inorganic organic hybrid compounds with organic cations as templates. Based on the above background, in this article, a new supramolecular compound named o-[C20H18N2O4][Mo8O26]0.5.H2O was obtained through hydrothermal method by reacting 1, 2-bis[4-nitrile-pyridine)-N-methylene]phenyldibromide (L1) with (NH4)6Mo7O24.4H2O. The compound was characterized by IR, PXRD, and single crystal X-ray analysis. Single crystal X-ray analysis shows that the compound consists of a [β-Mo8O26] 2–, a dicarboxylic acid chelating ligand and a water molecule. This compound exhibits good catalytic activity towards MB. The degradation rate of MB by photocatalysis of compound 1 was 75.2% . The novelty of this work lies in the synthesis of a cyano-hydrolyzed ligand and the high efficiency of MB degradation of the compound.

Sustainable nanohybrid of CaO with rGO for efficient photocatalytic removal of wastewater pollutants

The prominent water pollutants, Safranin (SF) and Eriochrome Black T (EBT) dye extensively used in plastic, leather, complexometric titrations, and textile industries, cause severe toxic impacts on the environment and human health. So, for their elimination, a cost-effective and sustainable hybrid of calcium oxide with reduced graphene oxide (rGO@CaO) was employed, synthesized using waste egg shells (precursor of calcium oxide), and thermal reduction of graphene oxide produced via modified Hummer's method. The sharp PXRD peaks confirmed the crystalline nature of the nanocomposite's pure and deformed spherical nanoparticles (20–40 nm). The removal of dyes was subsequently studied using the rGO@CaO nanocomposite (5–25 mg) at specific reaction conditions investigated (pollutant: 10–50 mgL-1, pH: 3–11, dark–sunlight). Under UV irradiation, the rGO@CaO nanocomposite demonstrated maximal degradation (SF: 97 % and EBT: 93 %) with 10 mg of catalytic dose at the initial dye concentration (10 mgL-1). The efficient photocatalytic efficacy of the rGO@CaO nanocomposite was supported by its small size, large surface area (48.06 m2g−1), higher negative zeta potential (-31.5 mV), and smaller bandgap (2.0 eV). Scavenger analysis revealed that holes, O2, and OH radicals play a crucial role in breaking the complex structure of SF and EBT. After degradation, safer metabolites developed, which was verified by LC-MS analysis. In conclusion, hybrid rGO@CaO nanocomposite is an efficient catalyst for industrial applications with broad potential due to its stability, higher charge separation, cost-effectiveness, and increased reusability (n = 8).

Recent progress on the remediation of dyes in wastewater using cellulose-based adsorbents

The increasing rise of hazardous dye (toxic and carcinogenic) in wastewater produced by multiple industries continues to become major threats to human health and environment, providing a big problem for conventional water treatment facilities to tackle this issue. Based on their appearance and physical characteristics, dyes are classified into different categories and are used in many industries. The presence of these dyes in water effluents imposes negative impacts on humans, ecosystem, and the aquatic organisms. To overcome these problems, numerous physical, chemical, and bio-based treatment methods have been researched and reported with different level of removal efficiencies based on the limitations of each approach and experimental conditions. Featuring high performance in removal efficiency, simplicity of usage, economical, and high recyclability of the absorbents have made adsorption as one of the most effective dye remediation methods. The creation of excellent nanomaterials has sped up the revolution in most industries. Green nanomaterials sourced from plant are the most promising technology as the raw materials exist in abundance in addition to the renewable resources. Nanocellulose from plant biomass exhibits excellent characteristics of renewability, biocompatibility with large surface area and high strength. In recent years, interest in utilizing nanocellulose and its derivatives as potential green approach for the removal of wastewater pollutants has emerged drastically. The present review focuses on the cellulose-based adsorptions for dye remediations, characterization aspects, parametric influence, modelling, and mechanisms.

Investigating the Potential of Greener-Porous Graphene for the Treatment of Organic Pollutants in Wastewater

Pharmaceuticals have emerged as a new class of ecological pollutants and have majorly contributed to harmful effects on the environment and human health. The presence of these pharmaceuticals in wastewater treatment plants, ground, and seawater has been reported widely. Organic dyes and other organic contaminants which are being considered as emerging contaminants are now in the race among the top organic pollutants that need effective treatment. Removal of these contaminants via green adsorbents has become an essential requirement towards a green and cleaner environment. Herein, we report the efficacy of the novel greener porous graphene obtained via the near-green synthesis method as an adsorbent material for treating seven organic pollutants: Methyl orange, Methyl red, Rhodamine-B, Ciprofloxacin, Atenolol, Ibuprofen, and Carbamazepine. Batch tests were conducted to investigate the effect of adsorption time and varying adsorbent dosages. The obtained greener porous graphene showed fast kinetics, which was determined to be guided by pseudo second-order kinetics and the maximum pollutant removal efficiency (>80%) was seen at a high adsorbent dosage (2 mL injected from a 5 g/L solution). Furthermore, the nonlinear adsorption modeling confirmed that the greener porous graphene followed the Langmuir model for the dye rhodamine-B sorption and the Freundlich model for all the other six contaminants. This greener porous graphene can be considered an effective adsorbent for the removal of organic pollutants in wastewater.

Decrease in the organic content of refinery wastewater by photocatalytic Fenton oxidation using iron-doped zeolite: Catalyst preparation, characterization, and performance

A Fe-exchanged zeolite photocatalyst was synthesized by applying an ion exchange method and used to examine the degradation of effluent from the petroleum industry. The exchanged zeolite catalyst was characterized by X-ray diffraction, X-ray fluorescence, Fourier-transform infrared spectroscopy, Naioatomic force microscopy, Brunauer-Emmett-Teller surface area, and Filed Emission Scanning Electron Microscopy-Energy Dispersive X-ray Spectrometer. Characterization of the catalyst confirmed its composition and phase but also showed a decrease in uniformity and crystallinity. The photocatalyst was tested under ultra-violet lamp irradiation for the removal of pollutants in wastewater from Iraqi petroleum refineries. Experiments were performed using a stirred batch reactor with an initial chemical oxygen demand of 492 mg/L. The exchanged zeolite was used as a catalyst and H2O2 was used as an oxidant. For synthetic wastewater, 99.84 % of organic pollutants were removed in 120 min. Chemical oxygen demand removal values were almost the same (85.29 and 81.67 %, respectively) for real wastewater obtained from the Dora Refinery and North Gas Company. Furthermore, the exchanged zeolite displayed excellent stability and low release of iron ions from the catalyst during the reaction (less than 11 mg/L). The catalyst was recycled five times with power consumption ranging from 691.18 to 826.96 kWh/kg COD.

Spatial-Temporal Variations of Zooplankton in Relation to Selected Limnological Parameters: A Case of Kisii Town Wastewater Treatment Plant, Kisii County, Kenya

Zooplankton have been used as bioindicators of water quality. In this study, we assessed the spatial-temporal variations of zooplankton in the Kisii town wastewater treatment plant and how they were influenced by limnological parameters between May and August 2021. Triplicate zooplankton samples were collected monthly for laboratory analysis. Physical parameters were measured in situ using a YSI multi-parameter probe while triplicate wastewater samples were collected for chemical parameters analyses ex situ. Eleven (11) zooplankton species were identified belonging to three groups. Cladocera was represented by 5 species (45.5 %), Rotifera by 4 species (36.4 %), and Copepoda by 2 species (18.2 %). The total zooplankton density recorded was 515IndL-1 with the family Cladocera dominating (57.7 %) followed by Copepoda (22.8 %) then Rotifera (19.5 %) with the least number in the population density. The limnological parameters measurements indicate considerable wastewater pollutant removal during polishing but negatively influenced zooplankton diversity. Therefore, zooplankton can be used to monitor wastewater treatment progress.