Effluent Treatment Research Articles

In-situ generation of bifunctional reagents via Al/C microelectrolysis for efficient coagulation–Fenton oxidation treatment of leachate MBR effluent

Coagulation–Fenton oxidation stands as a prevalent method for organic pollutant removal from MBR effluent in landfill leachate. However, its dependence on intricate coagulant preparation and hazardous H2O2 handling presents challenges in logistics. Herein, a novel Al0/C–N, Cl composite was developed via high-energy ball milling and high-temperature sintering, which facilitates in situ generation of H2O2 and aluminum salt coagulant upon stirring in oxygen-containing aqueous solutions. Under conditions of 2 g/L Al0/C–N, Cl and initial pH 9, H2O2 production achieved 459 mg/L within 1 h, yielding an Al3+/H2O2 bifunctional reagent. Subsequent coagulation in MBR effluent and Fenton oxidation achieved removal efficiencies of 85.5 %, 76.4 %, and 99.3 % for UV254, total organic carbon, and chromaticity, respectively. The efficient degradation of refractory fulvic-like substances was obtained from this novel “coagulation–Fenton” hybrid process without additional coagulants and H2O2. These results illustrated that the hybrid process is a promising and efficient technology for the advanced treatment of landfill leachate.

Development of graphene oxide and magnesia immobilized kaolin supported dual biopolymeric hybrid material for methyl orange and malachite green removal from water

Industrial usage of various dyes seriously depends on the efficient treatment of industrial effluents. Efficient retention of waste matter using a variety of adsorbent materials has as a result turned into dangerous. In this research article, graphene oxide (GO) cum magnesium oxide (MgO) impregnated kaolin (KA) based chitosan (CS) and pectin (Pect) composite namely GO/MgO/KA/CS-Pect as an adsorbent material for effective methyl orange (MO) and malachite green (MG) removal in aquatic system. The physico-chemical properties like bonding, structural morphology and elemental composition of GO/MgO/KA/CS-Pect were explored with numerous sophisticated instrumental techniques viz., FTIR, SEM, XRD, EDAX and elemental mapping analysis. The influencing parameters of adsorption method, with effect of reaction time, solution pH, dosage, pHzpc, initial MO/MG concentration and temperature were investigated for MO and MG removal under batch scale. The removal of MO and MG rate of the GO/MgO/KA/CS-Pect was incredibly fast and the adsorption kinetic method was driven with intraparticle diffusion (IPD) and pseudo-second-order (PSO) kinetic models. The adsorption isotherm strongly well-adapted with Langmuir isotherm and the maximum removal efficiency of GO/MgO/KA/CS-Pect was found to be 45.50 and 42.00 mg/g for MO and MG respectively within 40 min. The MO and MG uptake by GO/MgO/KA/CS-Pect was majorly owing to chemical adsorption namely electrostatic adsorption, hydrogen bonding and π-π interaction mechanism. The prepared GO/MgO/KA/CS-Pect was productively regenerated with absolute ethanol and could be repetitively reused. This exploration reveals the feasibility and selectivity of the GO/MgO/KA/CS-Pect as genuine adsorbent material for removal of MO and MG from the aquatic system.

Comparative Analysis of Concentrations of Heavy Metals in Surface Water of Nafada, Ashaka and Almakashi Corridors of River Gongola, Nigeria

A study on comparative analysis of heavy metals concentrations in surface water was carried out in three selected stations: Nafada, Ashaka and Almakashi along the corridors of River Gongola in Gombe state for a period of eighteen months. The water samples were collected in triplicate from the sampling stations. Water samples were collected using sampling bottles of 250ml dipped below the water surface for water collection. Zinc, lead, copper, cadmium and manganese were determined using Atomic Absorption Spectrophotometer. The result elucidates that most of the heavy metals were found to be within the recommended ranges as compared to standard limits. The result of concentrations of heavy metals in the surface water elucidates that there was a significant difference (P>0.05) among the months with respect to zinc and there was no significant difference in the concentration of lead (P<0.05). The concentrations follow the order (Zn >Cd>Cu>Mn>Pb). The higher concentration of heavy metals was found in Ashaka corridors with Zinc concentration ranging between 0.99±0.01 and 0.33±0.01, Cadmium 0.88±0.02 and 0.03±0.00, Cupper 0.58±0.02 and 0.14±0.02, Manganese 0.87±0.56 and 0.17±0.01, Lead 0.28±0.36 and 0.01±0.01. The wastewater from the cement effluent factory in Ashaka might have impacted negatively on the water chemistry by elevating the levels of some heavy metals. Therefore, more intensive treatment of the factory effluents before discharging into the River Gongola is recommended.

Advanced chitosan-based composites for sustainable removal of Congo red from textile wastewater

The non-biodegradable Congo red (CR) dye which is widely used in textile industries has poses carcinogenic risks due to its complex reactions that may generate benzidine. Effective treatment of industrial effluent containing CR dye is imperative. This study assessed chitosan (Cs) and chitosan/fly ash (Cs/Fa) composites for biosorbing CR dye from synthetic textile wastewater. Fly ash varied in the range of (1:0.25–1:1) with chitosan to assess adsorption performance. Characterization techniques included FTIR, SEM, EDX, BET, and zeta potential analyses. Response surface methodology guided the determination of optimal variables. The study examined Cs and Cs/Fa dosage (A), time (B), and initial dye concentration (C) effects on CR removal. Incorporating fly ash substantially cut adsorption costs by 50% while enhancing dye removal up to 85% at pH 6. Improved acidic stability of chitosan (Cs/Fa 1:0.75) was notable. Chitosan (Cs) exhibited a high Congo red removal efficiency of 98% while the chitosan/fly ash (Cs/Fa) composites showed a substantial removal efficiency of 94%. Optimal conditions were 2 g L−1 of adsorbents, initial CR concentration of 40 mg L−1 for 120 min. Freundlich isotherm model best described adsorption behavior. Pseudo-second-order kinetics correlated significantly (R2 = 0.999). This study showed the potential of Cs and Cs/Fa bio-composites for effective textile wastewater treatment.

Adsorptive removal of naproxen onto nano magnesium oxide-modified castor wood biochar: Treatment of pharmaceutical wastewater via sequential Fenton's-adsorption process.

This current investigation explored the thermal conversion process of castor wood into biochar, which was subsequently harnessed for removing naproxen from pharmaceutical industrial effluent via adsorption. Surface composition analyses conducted through scanning electron microscopy-energy dispersive X-ray, laser-induced breakdown spectroscopy, and Fourier-transform infrared studies unveiled the presence of nano MgO particles within the adsorbent material. Employing optimization techniques such as response surface methodology facilitated a refined approach to batch study. The optimized conditions for batch naproxen sodium (NPX) adsorption on nano-MgO-modified biochar were identified as pH 4, 1.5 g/L adsorbent dosage, and a 120-min contact time maintaining a constant NPX concentration of 10 mg/L. The adsorption capacity was calculated to be 123.34 mg/g for a nano-magnesium oxide-modified castor wood biochar (modified biochar) and 99.874 mg/g for pristine castor wood biochar (pristine biochar). Fenton's reagents comprising 15 mM of FeSO4 (7H2O) and 25 mM of H2O2 have been scrutinized under conditions of pH 3.0, a reaction time of 30 min, a temperature of 30°C, and stirring at 120 rpm, followed by batch adsorption treatment. The COD, NH3-N, NO3 -, PO4 3-, and NPX removal percentages was found to be 90%, 87%, 79%, 80%, and 90%, respectively. Thus nano MgO-modified biochar holds promise of treatment of pharmaceutical effluent.

P-32 powdered activated carbon detoxifies potentially toxic elements in the Kumasi Abattoir Ghana effluent

Industrial activities, particularly from abattoirs without effluent treatment facilities, threaten ecosystems, releasing a spectrum of potentially toxic elements (PTEs) into the environment. With a defunct wastewater treatment plant (WTP), exploring a low-cost but efficacious and eco-friendly adsorbent for the Kumasi Abattoir Ghana (KAG) effluent treatment is warranted. The study is the first attempt to utilize activated carbon (AC), such as the P-32 Powdered AC (PAC) brand, to detoxify PTEs—Cadmium (Cd), Copper (Cu), Zinc (Zn), Iron (Fe), and Lead (Pb)—in Ghana’s abattoir effluent. The adsorbent was manufactured and supplied by the Climate/Environmental Research and Technology (CLERET) Laboratory, one of the Research and Development (R&D) departments of Explore Scientific Innovations (ESI) Ltd., Ghana, using palm nutshell wastes as precursor. The study systematically evaluated the efficiency and adsorption prowess using incremental masses of 0.5, 1.0, 1.5, 2.0, and 2.5 g of the adsorbent/100 ml effluent, with three replicates per experimental unit in one cycle application of the adsorbent. The PTE concentrations were determined using standard methods before and after applying the adsorbent. Three adsorption isotherm models Langmuir, Freundlich, and Elovich, were applied to investigate the adsorption mechanisms governing the PTEs. The model performance was evaluated using R2 and Root Mean Squared Error (RMSE) metrics. The findings unveiled varied percentage removal efficiencies (% Rs), with Zn exhibiting the highest (79.64 %) at 2.5 g and Cd the least (7.8 %) at 0.5 g, of the carbon. The Freundlich isotherm emerged as the most robust model, consistently exhibiting the highest coefficient of determination (R2) with the lowest RSME values. Fe and Cd had the highest and lowest adsorption capacity (Kf) of 0.181 and 0.001, respectively. The Freundlich exponent (nf) values were within the favorability range of 1–10. The PTE adsorptions were physical rather than chemical. P-32 PAC provided a promising avenue for abattoir effluent management.

Optimization of the use of Moringa oleifera in wastewater treatment by rotational central composite design

Textile effluents have a complex waste composition due to the various compounds present and their resistance to degradation. Given the harmful effects of these pollutants on aquatic ecosystems, adequate treatment before disposal is essential, usually involving chemical processes such as coagulation and flocculation. This study optimizes textile wastewater treatment using Moringa oleifera as a natural coagulant through Rotational Central Composite Design (RCCD), a type of Response Surface Methodology (RSM), aiming to improve color removal, a key factor for effluent quality. By exploring Moringa oleifera as a sustainable alternative, the research provides new insights into environmentally friendly coagulant use and treatment optimization. The treatment’s effectiveness depends on the coagulant dosage, the energy applied, and the pollutant concentration. Dye removal was evaluated using spectrophotometry, and the evaluated factors in the optimization process were slow and fast mixing times, coagulant dosage, and pollutant concentration. The study identified pollutant concentration and slow mixing time as the most influential factors in treatment effectiveness. The model achieved a coefficient of determination (R²) of 87.9 %, and maximum dye removal reached 80.2 % under optimal conditions: 30 mL of coagulant, 20 min of slow mixing, 2 min of fast mixing, and a pollutant concentration of 300 mg ∙ L−1. The average removal efficiency was 47.86 %, indicating that natural coagulants offer a viable alternative for textile effluent treatment.

373 Effect of Cu and Zn contents in growing finishing pig diets on animal performance and Cu and Zn content in manure, according to three manure management chains

Abstract Copper (Cu) and zinc (Zn) are essential nutrients for swine. However, as pigs have a low retention rate for these elements, more than 90% of ingested Cu and Zn are excreted, mainly in feces. After spreading manure, these trace elements could accumulate in the soil and potentially have negative environmental effects. Moreover, Cu and Zn are also limited natural resources that should be preserved. A better understanding of the behavior of these elements throughout the feed-animal-effluent-treatment continuum according to feed composition and manure management chain is thus required to propose alternative ways to reduce these environmental impacts. Three feeding strategies differing in their Cu and Zn contents were compared in 72 growing-finishing pigs raised in individual pens [from 24.3 ± 3.3 up to 110 ± 9.0 kg body weight (BW), one-half males; and one-half females] a first diet with Cu and Zn at maximum EU regulation levels (20 and 100 ppm of Cu and Zn, respectively; REG), a second diet without any Cu and Zn supplementation (5 ppm Cu, 30 ppm Zn; WS) and a third diet with Cu and Zn at an intermediary level (10 and 50 ppm of Cu and Zn; INT). Cu and Zn were supplemented as Cu2O (CoRouge, Animine) and ZnO (HiZox, Animine), respectively. Eighteen additional finishing pigs (6 per diet) were raised in digestibility cages for excreta collection over 10 d, and their feces were submitted to two types of manure treatment: anaerobic digestion (AD) and composting with straw. Over the entire experimental period, the dietary Cu and Zn content did not influence growth performance of pigs. The Cu and Zn concentrations of the feces decreased linearly (P < 0.001) with dietary content from 191 and 834 (REG) up to 63 and 359 (INT) and 40 and 213 (WS) mg Cu and Zn/kg dry matter (DM) respectively. After both manure treatments, the degradation of the organic matter resulted in a significant increase (twice as much) in Cu and Zn concentration per kg of DM. Feeding strategy appears to be the main lever to reduce the Cu and Zn content of effluents. However, in the context of the diversification of manure management strategies, it is also important to take into account the effect of the effluent collection and treatment chain (e.g., spreading of raw slurry, phase separation, anaerobic digestion, composting), which has also an impact on the behavior of Cu and Zn and consequently on the risk for the environment.

Novel wastepaper nanocellulose/chitosan‐based nanocomposite membrane for effective removal of the textile dye Congo red from aqueous solution

AbstractDevelopment of a cost‐effective and environmentally friendly method to treat dye wastewater is of utmost importance. In this experimental study, wastepaper was used as the raw material for the extraction of cellulose nanocrystals to fabricate a nanocomposite membrane with chitosan. During the extraction process, acid hydrolysis (Sulfuric acid) followed by bleaching (hydrogen peroxide) was adopted. To confirm the nano‐range, particle size analysis, and FESEM were performed, which confirmed the presence of particles in the nano‐range ranging from 313.8 to 122.1 nm and FESEM observed results showed transformation of fibrous to rod shaped nanocrystals after acid hydrolysis. After successful nanocomposite fabrication a porous sieved network of membrane was observed and after adsorption successful adhesion of dye molecules over the membrane matrix was also confirmed. FTIR data showed that during adsorption mechanism some of the prominent peaks gets disappeared suggest interaction of dye molecules onto the nanocomposite. The contact angle of 21.0° was observed for the ChNC3 nanocomposite showed super hydrophilic behavior. Tensile strength was also observed in terms of young's modulus, ultimate strength, and elongation at break. The elasticity and stiffness of a material are usually indicated by its young modulus. In AH CNCs and ChNC3, the young modulus was seen to be increasing from 195< 693, respectively. On the other hand, the ultimate strength indicates AH CNCs and ChNC3 and shows a downward trend of 1.56> 0.316, respectively. Furthermore, the potentiality of the nanocomposite membrane was analyzed for Congo red dye in synthetic wastewater prepared in the laboratory. During the batch study, various working parameters were taken such as initial dye solution (20–100 ppm), pH (1–7), contact time (10–60 min), and dosage (0.1–0.5 mg/L). To know about adsorption, Langmuir and Freundlich isotherm were analyzed it was observed that Freundlich isotherm show best fitted modeling with R2 = 0.99, and n = 1.6 showing favorability of the heterogeneous adsorption. To determine the interaction between the adsorbate and adsorbent, pseudo first order and pseudo second order kinetics models were analyzed, and it was observed that chemisorption interaction followed between the adsorbate and adsorbent. Thermodynamic parameters were analyzed, which confirmed the spontaneous and favorable adsorption mechanism. To avoid fouling problems and maintain cost effectiveness, the resulting, nanocomposite membrane was desorbed using an appropriate solvent. After 5 cycles, the desorption rate decreased from 54% to 38%. This developed nanocomposite membrane appears to be effective in effluent waste treatment because of its simple formulation approach.

Removal of pollutants from pharmaceutical wastewater through electrofenton membrane bioreactor (EFMBR)

The treatment of effluent with diversified membrane technology related processes is not satisfying due to its own disadvantages and as a result the standard limits prescribed could not be met. This research work mainly focuses on the elimination of impediments associated with membrane bioreactors (MBRs). The irreversible fouling was found to greatly reduce by the addition of electrochemical pre-treatment processes with MBR. Chemical Oxygen Demand (COD) and Total Dissolved Solids (TDS) are the majorly considered water parameters and they are evaluated in the case of integrated electro-fenton membrane bioreactor (EFMBR), which is a hybrid technology comprising of electro-fenton pretreatment process with ozonation and MBR technology. This is proved to be highly effective with an excellent reduction percentage of 92 % COD and 50 % TDS respectively. Gas chromatography (GC) analysis of the pharmaceutical effluent upon treatment in EFMBR justified the quantitative reduction of pharmaceutical compounds. The results obtained on experimentation of EFMBR clearly indicated that there is a little internal and external fouling which is significantly proved through Hermia modelling and Scanning Electron Microscopy (SEM) analysis. The most eminent result obtained in this study were the efficacy of EFMBR to operate without the issue of filamentous bulking and it supported that electro-fenton could have played the major role for the achievement of eradicating fouling in EFMBR. The results obtained from this process gives an insight to researchers to overcome the irreversible fouling in industrial and municipal water treatment. The outcome of this study shows the insightful way employing this technology in water treatment industries could highly reduce the environmental problems.

MoS2@MIL-53 (Ni) nanocomposite for water splitting and water remediation through real time effluent treatment

A novel molybdenum disulfide@ materials institute of Lavoisier (MoS2@MIL-53 (Ni)) hetero-structure material has been designed to act as a hydrogen/oxygen generator and as a water remediation agent. Two-dimensional layered MoS2@MIL-53 (Ni) nanocomposites were prepared through the hydrothermal method. Flower and layered morphology were observed for MoS2, and MIL-53 (Ni), respectively in the field emission scanning electron microscopy (FESEM) images. The MoS2@MIL-53 (Ni) nanocomposite demonstrated a high dye degradation efficiency of ∼98 % and ∼96 % for Rhodamine B (RhB) and bodactive blue (BAB) within 80 minutes of time duration, respectively. In the case of untreated textile industrial effluent (TIE), the nanocomposite achieved an efficiency of around 86 % over a period of 9 hours. The ultraviolet-visible absorption spectra of RhB, BAB, and TIE displayed peaks at ∼565 nm, 665 nm, and 530 nm, respectively. Additionally, the nanocomposite exhibited excellent stability over five cycles when tested against RhB. During hydrogen evolution reaction (HER), MoS2@MIL-53 (Ni) nanocomposite showed a Tafel slope of 105 mV/decade and overpotential of −0.073 V vs. RHE. Similarly, oxygen evolution reaction (OER) studies exhibited a reduced over potential at 0.49 V vs. RHE @ 10 mA/cm2 and the Tafel slope was calculated to be 42 mV/decade. Further, the chronoamperometry analysis of MoS2@MIL-53 (Ni) confirmed that the sample exhibited relatively good stability with respect to both HER and OER analysis for 24 hours. This is indicative of MoS2@MIL-53 (Ni)’s structural stability and its strong electrocatalytic activity.

Investigating the impacts of a recirculation sedimentation application on microalgae biomass cultivation in wastewater treatment

Commercial microalgae production is often interrupted by contamination, leading to short production cycles, reinoculation needs, and culture collapses, significantly increasing costs. This study focuses on investigating Recirculated Sedimentation Application (RSA) to control contamination in microalgae culture systems used for wastewater treatment. Chlorella vulgaris culture was grown in an unsterilized mixture of tertiary treatment effluent and centrate of anaerobic digestion wastewater sludge over a 90-day experimental period. 60 L raceway reactor was operated under a light intensity of 275 μM m−2.s−1 with a 16:8 h light-dark photoperiod. To evaluate the effect of RSA on biological-based problems, the experiment was conducted in three phases. The benefits of utilizing RSA were established through the following observations: effective removal of contaminants at an acceptable level without releasing the culture; extension of the biofilm formation time on the inner walls; inhibition of heterotrophic bacteria and nitrification; enhancement of the suspended solids retention capacity of the raceway tank (up to 770 mg.L−1); and improvement in ammonium removal rate to approximately 30 mg.L−1d−1. The ideal salinity level for both ammonium removal and biomass concentration in RSA should be below 0.02%. These findings demonstrate the potential of phycoremediation for sustainable wastewater treatment and contribute to environmental bioremediation strategies.

Evaluation of a pilot-scale anaerobic biofilm reactor for the treatment of slaughterhouse effluents in rural areas

ABSTRACT Rural slaughterhouses often lack strict effluent treatment rules, resulting in inadequate treatment prior to release into water bodies. Slaughterhouse wastewater (SWW) is a high-strength effluent, posing risks of contamination to ecosystems and human health. To tackle the need for suitable technologies in these areas, this study evaluated a 215 L pilot-scale fixed-bed biofilm reactor (FBBR), known for its simplicity in implementation, operation, and maintenance. During the operation, an initial startup period, with the liquid fraction of fruit and vegetable waste (LF-FVW) was conducted, followed by a gradual transition to SWW, creating a co-digestion period during the substrate transition. Organic load variations (1.59, 3.35, and 4.00 kgCOD/m3·d), corresponding to flow rates of 50, 75, and 120 L/d, respectively, were implemented to address potential alterations in effluent concentration and composition in authentic rural settings. Removal rates of up to 83.69, 91.81, 87.00, and 92.00% were achieved for COD, sCOD, TS, and VS, respectively, with an average removal of 32.00% for TN, and biogas production exceeded 300 L/h at 4.00 kgCOD/m3·d. These results suggest that FBBR implementation in rural areas effectively confronts SWW treatment challenges by reducing contamination, generating biogas, and adapting to rural conditions.

Harnessing hazardous wastes: the production, characterization, and performance of controlled low strength materials using common effluent treatment plant sludge

India's rapid industrialization has led to an increase in waste generation, necessitating efficient disposal methods. This research addresses this challenge by exploring the use of Common Effluent Treatment Plant (CETP) sludge, a hazardous waste, in the production of Controlled Low-Strength Materials (CLSM). The study aims to mitigate the environmental impacts associated with CETP sludge disposal while providing a sustainable solution. To assess the feasibility of this approach, an experimental program was conducted with variations in the mix ratio of CETP sludge and slag sand, a byproduct of steel production. The properties of the produced CLSM, such as flowability and unconfined compressive strength (UCS), were thoroughly examined using Scanning Electron Microscopy, X-ray Diffraction, and X-ray Fluorescence analyses. The results reveal that the CLSM produced with CETP sludge and slag sand exhibits promising performance, with excellent flowability and UCS values ranging from 1.8 to 5.5 MPa. This research underscores the potential of waste materials in creating sustainable and environmentally friendly construction materials, contributing to effective waste management practices and sustainable industrial growth.

Comparative Study of Adsorbents for Treatment of Industrial Effluent

Water contaminated with various impurities is considered as wastewater and industrial wastewater obtainedfrom industries is known as effluent. The industrial effluent adversely affects the aquatic ecosystems,deteriorate human health, and degrades overall environmental quality. Treatment of such effluent withadsorbent is one of the most efficient and cost-effective method. In the present study, industrial effluent wastreated with various bio-adsorbents obtained from orange peels, cotton, neem tree bark. Effect of adsorptionon parameters like pH, COD, BOD, TDS and TSS were determined and their results were compared withcommercial grade activated charcoal. For majority of the parameters, the effectiveness of adsorbent varied as:activated charcoal > tree bark-based adsorbent > cotton-based adsorbent > orange peels-based adsorbent.Effect of pretreatment- acid treatment- was also examined for cotton and tree bark-based adsorbent.Phosphoric acid was proven to be better acid for pretreatment in comparison with sulfuric acid. For tree barkbased adsorbent treated with phosphoric acid, % removal for COD, BOD, TDS and TSS were 46.5 %, 57.06%, 35.51% and 90.43% respectively

APPLICATION OF PLANT SEED BIO-COAGULANT IN THE REMEDIATION OF ENVIRONMENTAL PAINT EFFLUENT

The discharge of industrial effluents into the environment has been a growing concern worldwide due to its adverse impacts on human health and the ecosystem. Paint effluent, in particular, poses a significant threat due to its high chemical oxygen demand (COD), total suspended solids (TSS), and colour. Conventional methods of treating paint effluent discharge require the use of chemical coagulants, which are expensive, non-sustainable, and can generate hazardous waste. The search for alternative and sustainable methods for treating industrial effluent has led to the exploration of natural coagulants derived from plant sources. One such source is watermelon seeds, which contain significant amounts of proteins that possess coagulating properties. This study aimed to investigate the potential of watermelon seed bio-coagulant (WSB) for the remediation of paint effluent discharge. The effects of the watermelon seed bio-coagulant dosage, pH, and agitation rate on the removal efficiency of the treatment process were evaluated. These results revealed that the bio-coagulant was effective. The optimum coagulant dosage, pH, and agitation rate were found to be 300mg/L,4, and a treatment time of 45 min, respectively, with BOD and COD removal efficiencies of 88.47% and 90.41%, respectively. Statistical optimization of the treatment process was performed using the response surface methodology (RSM). The results revealed that the quadratic model developed using RSM was statistically significant with a high coefficient of determination (R2 = 0.9958). The analysis also revealed that bio-coagulant dosage and pH are the major factors affecting the efficacy of the treatment process. The optimized conditions led to removal efficiencies of88.95% and 90.61% for BOD and COD, respectively, indicating that watermelon seed bio-coagulant could be an effective and sustainable alternative for treating paint effluent. The results of this study suggest that the use of watermelon seed bio-coagulant is a promising approach for optimizing the paint effluent treatment process. It is a cost-effective and eco-friendly alternative to conventional coagulants used in wastewater treatment and has demonstrated efficacy in treating industrial wastewater. This study presents a sustainable and eco-friendly approach to the treatment of paint effluent discharge using a natural coagulant derived from a waste product.

Impacts of fish pond effluent on the water quality of an afrotropical stream: a comprehensive evaluation using the water quality index

This study highlights the importance of managing fishpond effluent to minimize its impact on aquatic environments. Fish effluents are a major concern worldwide in aquatic environments. It also provides information on the impacts of effluents on the water quality index of streams when released into aquatic environments. Streams and fishponds were sampled bimonthly for two annual cycles, covering different sampling stations both upstream and downstream of the fishpond effluents at 50-m intervals. Water quality parameters associated with in situ conditions were determined in the field. In the laboratory, other physicochemical parameters were determined via proper standard protocols. The results of the study revealed that water quality parameters such as turbidity, total suspended solids, total solids, conductivity, total dissolved solids, dissolved oxygen, biological oxygen demand and organic matter recorded in water samples collected from 50 m upstream at the point of effluent discharge were significantly (p < 0.05) different from those recorded at other sampling stations. The WQI value of the discharge point was higher than the WQI recorded in both the upstream and downstream sections of the stream. The findings of this study showed that the point of discharge of fishpond effluents is particularly concerning for the receiving stream compared with other sampling points. This localized area has experienced marked deterioration in water quality, posing significant threats to the health and biodiversity of aquatic ecosystems. The effluent's impact, though slight when dispersed in the receiving waterbody, underscores the necessity for adequate management practices to mitigate its adverse effects. Effective strategies, including regular monitoring, effluent treatment, and sustainable pond management, are imperative to ensure the long-term health and resilience of the aquatic environment.

Isolation and Characterization of Plant-Growth-Promoting Bacteria Associated with Salvinia auriculata Aublet.

Salvinia auriculata Aublet is a floating aquatic plant, capable of absorbing the excess of nutrients and water contaminants and can be used in effluent treatment plants. The ability to survive in degraded areas may be related to the association with beneficial bacteria capable of promoting plant growth. However, little is known about the microbiota associated with this aquatic plant and its potential application to the aquatic environment. In this sense, this work aims to identify bacteria associated with S. auriculata that could be able to promote plant growth. Eighteen bacterial strains were identified by sequencing of the 16S rRNA gene, belonging to the genera Agrobacterium, Bacillus, Curtobacterium, Enterobacter, Pseudomonas, Siccibacter, and Stenotrophomonas. All isolates produced indole compounds, 12 fixed N2, and 16 solubilized phosphate. A new strain of Enterobacter (sp 3.1.3.0.X.18) was selected for inoculation into S. auriculata. For this purpose, 500 mL of nutrient solution and 1 g of the plant were used in the control and inoculated conditions. Enterobacter inoculation promoted a significant increase (p ≤ 0.05) in fresh plant biomass (17%) after 4 days of cultivation. In summary, the present study characterized 18 plant-growth-promoting bacteria isolated from S. auriculata with potential for biotechnological application, such as the production of bioinoculants or biomass resources, to protect or improve plant growth under conditions of stress.

Radical decomposition of hydrogen peroxide catalyzed by iodide for degradation of organic dyes

The decomposition of hydrogen peroxide into hydroxyl radical, a powerful oxidizing agent, has aroused the interest of the scientific community due to the numerous possible applications, mainly in the treatment of effluents. In this work, the potential of using iodide ions as precursors of the hydroxyl radical was evaluated. Iodide, in addition to being theoretically viable, simultaneously leads to the production of molecular iodine, which also has an oxidizing characteristic, and can contribute to the efficiency of the process. The results demonstrated that iodide ions act by promoting the radical decomposition of H2O2 and that the process is dependent on the pH of the reaction medium, with the generation of radical hydroxyl only manifesting itself at pH 2.5 and 3.0. The removal results proved that the anionic or cationic nature of the dye interferes with the reaction mechanism. For methylene blue, a cationic dye, a small portion of TOC was removed by oxidation (7.9 to 20.6%) and the remainder occurred by adsorption (79.4 and 92.1%). The interaction of methylene blue with the surface of molecular iodine prevents its contact with the iodide ions present in the reaction medium, allowing it to remain in a solid state in solution and act as an adsorbent, contributing to better efficiency. For the tartrazine yellow dye, an anionic dye, there was no formation of solid iodine, indicating the absence of an adsorptive process, with the oxidation mechanism, showing removal of 11.3 to 18.9%, similar to the results found for the removal of blue. methylene by oxidation.

Response surface methodology-based optimisation of adsorption of diclofenac and treatment of pharmaceutical effluent using combined coagulation-adsorption onto nFe2O3 decorated water chestnut shells biochar.

This work involved the preparation of pristine and iron nanoparticle-loaded biochar from a water chestnut shell to remove diclofenac sodium (DCF) containing effluent of pharmaceutical origin. To create suitable forecasting equations for the modelling of the DCF adsorption onto the adsorbent, response surface methodology (RSM) was used. The parameters, e.g. pH, adsorbent mass, DCF concentration and contact time, were used for the modeling of adsorption. The RSM model predicts that for 98.0% DCF removal, the ideal conditions are pH 6, an adsorbent dose of 0.5 g L-1, and a contact time of 60 min with an initial adsorbate concentration of 25 mg L-1 at 303 K. The maximum capacity deduced from the Langmuir model was 75.9 mg g-1 for pristine water chestnut shell biochar (pWCBC) and 122.3 mg g-1 for magnetically modified nano-Fe2O3 biochar (mWCBC). Under equilibrium conditions, the Langmuir model was the best-suited model compared to the Temkin and Freundlich models. The adsorption data in this investigation efficiently fitted the pseudo-second-order model, emphasizing that chemisorption or ion exchange processes may be involved in the process. The WCBC demonstrated recyclability after 10 cycles of repeated adsorption and desorption of DCF. A combined coagulation adsorption process removed COD, NH3-N, NO3-, PO43-, and DCF by 92.50%, 86.41%, 77.57%, 84.54%, and 97.25%, respectively. This study therefore shows that coagulation followed by adsorption onto biochar can be a cost-effective substitute for conventional pharmaceutical wastewater treatment.