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Carbon nanotubes (CNTs), as a new type of carbon material with complete molecular structure, have great application potential in the field of nanocomposites. In this study, carbon nanotubes were first surface modified to give them good hydrophilicity. Subsequently, the nanocomposite coagulant (PASS-T) with different modified CNTs (m-CNTs) contents was prepared by alkaline titration method. The CNT, m-CNT, PASS and PASS-T were characterized by FTIR, XRD and XRF. Then the coagulant was applied to oily sewage, and the coagulation results showed that the PASS-T (0.1%) had the best oil reduction rate (92%) and turbidity reduction rate (97%). Appropriate addition of m-CNT can increase the local concentration of coagulant at the molecular level, making the flocs of oily sewage larger. It can be found by SEM that PASS-T produces large and knotted flocs in oily sewage. Finally, the residual turbidity and oil removal rate of the different coagulants were statistically analyzed. [ABSTRACT FROM AUTHOR]

The rapid expansion of global urbanization and industrialization has significantly increased the discharge of municipal wastewater, leading to issues of carbon emissions and energy consumption when using traditional biological treatment processes. This study proposes an innovative process that couples iron coagulation with microalgal–bacterial granular sludge (MBGS), with optimization and regulation based on operational conditions. The study found that the coagulation performance achieved optimal levels at an iron concentration of 25 mg/L and an anionic polyacrylamide concentration of 1 mg/L, which could remove approximately 61% of the organics and over 90% of phosphorus from raw wastewater. By relying on heterotrophic microorganisms, such as Proteobacteria, Bacteroidota, and Chloroflexi, along with the synergistic interaction between algae and bacteria, the subsequent MBGS process could further effectively remove organics over the day-night cycles. Moreover, the addition of inorganic carbon sources of NaHCO3 increased the abundance of denitrification-related genes, reduced the accumulation of nitrite within MBGS, and led to effective total nitrogen removal. These results indicate that the iron coagulation–MBGS coupling process can efficiently treat municipal wastewater, offering potential for environment-sustainable pollutant removal with reduced energy consumption. These findings provide valuable insights for the practical engineering application of MBGS in wastewater treatment systems aiming for carbon-neutral wastewater treatment. [ABSTRACT FROM AUTHOR]

Microplastics (MP), fragments of plastic generally defined as, less than 5 mm in size, originating from various urban sources, have become a significant environmental concern due to their widespread presence and potential impacts on ecosystems. This study investigates the efficiency of an advanced wastewater treatment plant discharging into the Mediterranean Sea in removing MPs from wastewater. The plant processes wastewater through a series of treatment stages, including screening, desanding, coagulation/flocculation, biological filtration, and sludge incineration. Samples were collected and analysed during three distinct campaigns (dry, rainy, and touristic seasons) to assess the plant's performance under varying conditions. Using matrix-representative sampling methodologies and Focal Plane Array micro Fourier-Transform Infrared Spectroscopy (FPA-µFT-IR) for MP quantification, the study measured MP concentrations and removal rates. The treatment plant demonstrated high removal rates of microplastics across different periods. Using a mass balance approach, the removal efficiency during the dry sampling period was 99.85%. In the rainy campaign, the efficiency slightly decreased to 99.11% due to increased runoff, while during the touristic period, the efficiency peaked at 99.95%. Polyester was identified as the predominant polymer type. The primary treatment stages, particularly coagulation/flocculation and lamellar settling, are most effective in MP removal. The majority of MPs are retained in the sludge, which is subsequently incinerated, preventing environmental discharge. This research demonstrates that a WWTP employing advanced treatment processes is not a source of MP to the environment but rather a sink. Despite variations in influent MP concentrations across different seasons, the plant consistently maintained high removal rates, effectively mitigating MP pollution. In this study, sludge incineration further ensured that MPs were prevented from entering the environment. [ABSTRACT FROM AUTHOR]

The search for eco-friendly materials has greatly evolved ahead of basic requirements encompassing sustainable practices. The selection of such sustainable material requires procedural systematic screening tests to facilitate decision-making. Water and wastewater treatment processes involve several chemicals, and they need to transition from commercial to natural materials owing to their environmental and economic concerns. The present study aimed to select and screen natural coagulants for wastewater treatment. The criteria assessment factors for the present study were easy availability, economic value, turbidity removal efficiency, and reduced sludge generation with high dewaterability. A standard jar test apparatus was used for the coagulation experimental runs. The physicochemical parameters were analyzed using standard methods. The results presented positive insights into the efficiency of tested natural coagulants, with the least turbidity removal of 83.3% by rice husk at 1gm/500ml and the highest being 96.4% by onion peel at 1gm/500ml. The sludge obtained after treatment with natural coagulants has presented an excellent dewaterability, with the least being 29.17% by tamarind seeds at 1gm/500ml and the maximum being 90.2% by coconut fibre at 1gm/500ml. From the study, was concluded that the screening method promoted the selection of the best coagulant type and dose and reduced the efforts and time needed to eliminate the non-performers. [ABSTRACT FROM AUTHOR]

The use of coagulants, such as ferric chloride hexahydrate, in wastewater treatment processes is known to induce pipe corrosion and to contribute to the discoloration of treated water. This study explores alternative approaches to sludge dewatering by evaluating the effectiveness of polymeric aluminum chloride (PAC) as a coagulant and polyoxyethylene alkyl ether (POAE) as a surfactant. The impacts of coagulation/flocculation were assessed using time to filtration (TTF) and a pressure filter press. The effects of certain coagulant and surfactant dosages were studied. The inputs were in the range of 105–1750 mg/L for PAC and 28–152 mg/L for POAE, which were determined based on zeta potential (ZP) measurements. The optimal concentrations were 876 mg/L for PAC and 114 mg/L for POAE, resulting in a TTF of less than 1 min. Moreover, the effect of pH on anaerobic sludge dewaterability was investigated. At a low pH below 8, the ZP reached the maximum value, and a higher pH resulted in a reduction in ZP. Under low-pH adjustments, it was observed that the dewatering performance of the POAE surfactant improved more significantly than that of the PAC coagulant. In addition, the effect of pressure was analyzed using a pressure filter under conditions favoring POAE, with relatively lower dosages and greater cost-effectiveness. In order to evaluate the solubility of organic matter under pressurized conditions, the filtrate's removal efficiency, chemical oxygen demand (COD), and total phosphorus (TP) were investigated. Solubilization did not occur at an increased pressure of around 10 bars. The findings presented in this study provide technical assistance for sludge treatment. [ABSTRACT FROM AUTHOR]

In this study, the effectiveness of sequentially applying coagulation and adsorption processes in treating soft drink industry wastewater was assessed based on COD removal. In the electrocoagulation method with iron electrodes, the highest COD removal occurred at 42%, achieved with a current of 9A and the natural pH of the wastewater at 5.51. In chemical coagulation, using FeCl3 •6H2 O as a coagulant, the highest removal rate of 23% was achieved at pH 5 with a coagulant dose of 2.5g/L. Activated carbon adsorption, in doses ranging from 10 to 40g/L, was applied to the effluents of both electrocoagulation and chemical coagulation at various contact times, up to 150 minutes, resulting in COD removal rates of 42% and 36%, respectively. According to the results, the COD removal efficiencies for the electrocoagulation-adsorption and chemical coagulation-adsorption systems were 66% and 51%, respectively. The findings of this study are important because they demonstrate the necessity of research on the use and development of physicochemical methods for the treatment of soft drink industry wastewater. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the applicability and efficiency of sequential coagulationflocculation (CF) and electrooxidation (EO) processes for cattle slaughterhouse wastewater by evaluating treatment efficiency and total operating cost values together. The effect of two different coagulant dosages (FeCl3 and alum) in the CF process and operating parameters such as current density (5 to 30 mA/cm² ), wastewater flow rate (0.9 to 3.6 L/h), and supporting electrolyte concentration (1 to 3 g NaCl/L) in the EO process on chemical oxygen demand (COD) and turbidity removal were investigated. During the first part of the study, the FeCl3 coagulant dosage worked better than other coagulants, eliminating 50% of the COD and 68% of the turbidity. Due to the insufficient removal efficiencies of COD and turbidity, a secondary treatment was required. In the second part of the study, a boron-doped diamond (BDD) electrode was used to treat the coagulated effluent in a continuous EO reactor. The COD and turbidity removal efficiency under optimum treatment conditions (j = 30 mA/cm², Q = 0.9 L/h, pH = 8.5, SE = 3.0 g NaCl/L, and hydraulic retention time = 1 hour) were calculated as 97.2% and 99.9%, respectively. At these optimum conditions, the energy consumption and total operating cost were calculated as 91.1 kWh/m³ (73.5 kWh/kg COD) and 3.50 US $/m³ (1.5 US $/kg COD), respectively. As a result, combined coagulation-flocculation and electrooxidation processes have proven to be very successful and cost-efficient for treating cattle slaughterhouse wastewater. [ABSTRACT FROM AUTHOR]

The vegetable oil industry uses high amounts of water as a process and contains high concentrations of various pollutants and compounds resistant to biodegradation. In this study, the coagulation/flocculation process was applied to treat these wastewaters that have a negative effect on the receiving environment. In coagulation-flocculation experiments performed with Al2(SO4)3.18H2O, the highest COD (92%) and Oil-Grease (89%) removal efficiencies were obtained at a coagulant dose of 800 mg Al+3/L. In experiments conducted with FeCl3.6H2O coagulant, the highest COD (88%) and Oil-Grease (89%) removal efficiencies were obtained at a dose of 600 mg Fe+3/L coagulant. This study demonstrated the effective use of the coagulation/flocculation process in the treatment of vegetable oil industry wastewater containing high COD and Oil-Grease. [ABSTRACT FROM AUTHOR]

Coagulation–flocculation is one of the most mature and effective process, which can remove most of the colloids. The objective of this study was to investigate a treatment for denim-washing wastewater by coagulation–flocculation and Fe/garnet filtration to evaluate the potential use of the sludge produced. The reaction time, stirring rate, dose, and coagulant agent using Ca2+, Mg2+, and Fe2+ as chlorides on the % removal of color, chemical oxygen demand, and turbidity were evaluated using an experimental design 32. The best chemical oxygen demand (49% of these low efficiencies may be related to chloride interferences), color (84.6%), and turbidity removal (82.3%) efficiencies were achieved at a dose of 1.4 g/L Ca2+, time of 20 min, and shaker speed of 50 rpm. Under these conditions, Ca(OH)2 commercial (Calidra® at 75–85%) was also tested, removing chemical oxygen demand, turbidity, and color by 67, 97, and 93%, respectively, at 1.4 g/L Ca2+. The effluent from the garnet filtration process was characterized, the pH was reduced from 11.8 initial to 7.7 final, and removals of 59.0% total organic carbon, 20.5% chemical oxygen demand, and 28.6% color. The effect of sludge from the coagulation–flocculation process with Ca(OH)2 was studied in Lactuca sativa seed. The life cycle assessment concluded that the treatment reduced the midpoint impacts of the environmental category indicators, such as freshwater eutrophication, marine eutrophication, freshwater ecotoxicity, marine ecotoxicity, human noncarcinogenic toxicity, land use, and mineral resource scarcity. Treated wastewater can be reused in the same process for denim washing. [ABSTRACT FROM AUTHOR]

This study investigated water recovery with the treatment of leather industry processes wastewater (washing, pickling, and degreasing units) using coagulation, ultraviolet/persulfate (UV/PS) treatment, and nanofiltration processes. Coagulation studies were carried out using alum as the coagulant, and the highest chemical oxygen demand (COD) removal efficiency was obtained at pH 7 for all the wastewater. The highest COD and total organic carbon (TOC) removal were 80.9 and 50.5% in the wastewater washing unit ( : 8 g/L, pH 7) and 76.5 and 96.1% in the wastewater degreasing unit ( : 16 g/L, pH 6) using UV/PS oxidation, respectively. High COD and TOC removal could not be achieved with UV/PS oxidation in the wastewater pickling unit. In the studies performed with NP030 nanofiltration membrane after UV/PS oxidation, the highest permeability and COD removal was achieved at pH 7 under 4 × 105 Pa pressure in wastewater washing and degreasing units. After 75 min of nanofiltration at pH 7 in washing and degreasing units, the total filtrate amount was 39.8 and 42.3 L/m2 h, respectively. COD concentration in the wastewater washing unit decreased from 4434 to 138 mg/L, while it decreased from 5833 to 212 mg/L in the wastewater degreasing unit with coagulation, UV/PS processing, and nanofiltration. As a result, the treatment of leather industry wastewater through separate streams with coagulation, UV/PS, and nanofiltration, washing, and degreasing unit wastewater provides very high COD removal. Also, it has been shown impossible to treat the pickling unit wastewater by UV/PS oxidation. [ABSTRACT FROM AUTHOR]

• Recycle of the coagulated Ti-loaded sludge to obtain functional C/TiO2 composites. • The first to evaluate the application of the Ti-loaded sludge derived C/TiO2 composites for anode of LIBs. • In-situ carbon-coated to enhance the structural integrity and improve Li+ transport of C/TiO2 composite. • The obtained C/TiO2 composites showed superior cycling performance to the commercial TiO2. Resource recycling from waste-water and sludge is an important part of the 14th Five-Year Plan in China. The emerging titanium-based coagulants have drawn growing attentions due to their strong coagulation capability in water purification and value-added Ti-loaded sludge production. Management and recovery of the high value-added sludge into functional nanomaterials is highly significant for both sludge reduction and environmental remediation. The present study was carried out to investigate the recycle of the coagulated Ti-loaded sludge to produce functional C/TiO 2 composites as the anode materials for lithium-ion batteries (LIBs). It is the first time that the application of the Ti-loaded wastewater sludge derived C/TiO 2 was evaluated for LIBs. The experimental results showed that the carbon coating through in-situ carbonization of the sludge produced the C/TiO 2 composites with a high specific surface area, stable structural integrity, and excellent electrochemical properties that would facilitate Li+ diffusion in long-term LIBs usage. The C/TiO 2 composites calcinated from the polytitanium sulfate-coagulated sludge at 800°C (N 2) exhibited the best electrochemical performance during the cycling tests (601 mAh/g at 100 mA/g after 200 cycles). The research work demonstrates the promising prospect of the recycle and value-added utilization of the Ti-loaded sludge in the production of high-performance C/TiO 2 composites for energy storage applications. This study provides a new way for the management and reuse of Ti-loaded waste-sludge. [Display omitted] [ABSTRACT FROM AUTHOR]

The present study aims to investigate the efficiency of a combined cheese wastewater treatment approach involving coagulation with ferric chloride coupled with a photo-Fenton-like oxidation process for potential reuse in irrigation. Laboratory-scale tests were conducted, examining the effect of various operational parameters on the treatment process. Specifically, the effects of initial wastewater pH, coagulant dosage, decantation time for the coagulation process, and initial pH, chemical oxygen demand (COD) concentration, and Fe3+ and H2O2 dosages for photo-Fenton-like oxidation were studied. Coagulation was found effective at natural pH of 6 and showed a highest removal efficiency in terms of COD (50.6%), biological oxygen demand BOD5 (42.1%), turbidity (99.3%), and least sludge volume generation (11.8% v/v) for an optimum coagulant dose of 400 mg Fe3+ L–1 and 8 h of decantation time. Thereafter, photo-Fenton-like oxidation (Fe3+/H2O2/UVA-300W) of the pretreated cheese effluent enhanced the removal of COD, BOD5 and TOC to 91.2%, 91.4%, and 97.5%, respectively, using the optimized conditions (pH = 3; [Fe3+] = 5.0 × 10−4 mol L−1; [H2O2] = 0.2 mol L−1 and tirr = 24 h). This study also shows that the proposed combined process allowed a significant phytotoxicity reduction toward lentil seed germination. The obtained outcome was encouraging and supports the possible use of the treated cheese wastewater as an additional water source for agricultural irrigation. [ABSTRACT FROM AUTHOR]

This study investigated the oxidation of wastewater generated during the production of glass fiber manufacturing material, which contains high organic carbon (18.32 g/L) and has a pH of 8.8, by chemical coagulation, electrocoagulation and electroadvanced oxidation techniques. It was determined that the total organic content (TOC) of wastewater was reduced by 53% using the chemical coagulation method. After electrocoagulation with Al/Al electrode pair for 300 minutes at 500 mA, 73% TOC removal was achieved at pH 8.8. While 50% TOC removal was completed in 2 h at 400 mA in electrocoagulation with Fe/Fe electrode pair, 71% TOC removal was obtained in the combined electrocoagulation/electro-Fenton process by adding hydrogen peroxide to the medium under the same conditions. In addition, it was also observed that the success of the anodic oxidation methods alone was lower. The electro-Fenton application after electrocoagulation was effective and provided 78% TOC but required work at pH 3 and a longer treatment time. [ABSTRACT FROM AUTHOR]

Recycled paper pulping wastewater (RPPW) will cause serious environmental problems due to the high loads of dissolved organic matter (DOM) and toxic components. In the present work, the degradation of DOM in the biologically treated RPPWs (cardboard wastewater (CW) and corrugated container wastewater (CCW)) by a combined coagulation and ozonation process was investigated. The optimal chemical oxygen demand (COD) removal of CW reached 73.64% at aluminum sulfate (Al2(SO4)3) dosage of 800 mg/l, aeration aperture of 10 μm, pH of 9, hydrogen peroxide (H2O2) dosage of 100 mg/l, and reaction time of 70 min. The optimal COD removal of CCW reached 55.76% at a poly-aluminum chloride (PAC) dosage of 700 mg/l, H2O2 dosage of 140 mg/l, and reaction time of 50 min. This study provided some insights into the change of DOM during the combined treatment through the use of UV–Vis spectroscopy and excitation-emission matrix spectroscopy (EEM). PAC and Al2(SO4)3 removed high molecular weight organic such as lignin and lignin-derived compounds to improve the biodegradability of the wastewater. Ozone oxidized high molecular weight organic with complex functional groups to low molecular weight organic with simple functional groups and even mineralization, and this phenomenon resulted in the COD of ozonation effluent significantly reduced. Thus, the results presented in this study support the application of the combined coagulation and ozonation process in treating RPPW. [ABSTRACT FROM AUTHOR]

Background: The adequate management of dairy effluent is of prime importance to mitigate environmental damages. In addition, its adequate treatment could enable its reuse inside the dairy industry, contributing to a sustainable economy. Results: The optimization of the coagulation/ flocculation/ sedimentation stage through a Box–Behnken Design was proposed using real dairy effluent and natural coagulant of Moringa extracted with CaCl2. Then, nanofiltration with a NF 270 membrane was applied, using the raw wastewater and the wastewater pre‐treated with coagulation/ flocculation/ sedimentation, enabling apparent color and turbidity removals of >98% in the three studied conditions. A satisfactory chemical oxygen demand (COD) removal of 88.9% was obtained only with the combination of the pre‐treatment by coagulation/ flocculation/ sedimentation followed by nanofiltration. When the effluent was subjected to nanofiltration directly, the COD removal did not reach 61%. Besides improving the removal values, the pre‐treatment improved the transmembrane flow, reducing the fouling and the membrane total resistance when compared to the dairy wastewater directly subjected to nanofiltration. Conclusion: When the wastewater was pre‐treated using the natural coagulant, the nanofiltration stage was improved because the membrane presented a lower fouling (~10%), lower total resistance and less calcium build‐up compared to direct nanofiltration of the wastewater (~60%). This indicates that the membrane lifespan can be extended when the pre‐treatment is applied. The quality evaluation of the treated effluent demonstrated that it presents the potential to be reused inside the dairy industry, which could greatly contribute to a sustainable and economic scenario. © 2023 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Response surface methodology (RSM) and Box–Behnken design (BBD) were investigated to optimize the coagulation–flocculation process (CF) of cardboard industry effluent using polyaluminum chloride (PAC) and cationic polyacrylamides (c-PAM). The aim is to identify the optimum combination of coagulant dose, pH, and flocculant dosage for the highest removal efficacy of chemical oxygen demand (COD) and anionic surfactant removal. According to the results, COD reduction was principally controlled by PAC and c-PAM, while anionic surfactant was affected by pH and PAC. In addition, COD and anionic surfactant removal models fitted well with the experimental results (R2 > 0.85). Coagulation/flocculation using optimum conditions of pH, PAC, and c-PAM led to the total removal of anionic surfactant and the reduction of more than 95% of COD. [ABSTRACT FROM AUTHOR]

This work reports a combined coagulation-electrocoagulation process using a biocoagulant from the Opuntia ficus-indica for treatment of cheese whey wastewater. The process parameters as pH, biocoagulant dosage, and current density were evaluated from the chemometric tools. A Box-Behnken design was used, having as responses the removal percentages of turbidity and chemical oxygen demand (COD). The results showed that for the studied variable ranges, linear models were obtained and the pH was parameter more significant for treatment proposed. The pH showed synergic effect with the investigated parameters, while the biocoagulant dosage and density current showed antagonistic effects. The desirability function was used to optimization of process, and suggested values were pH 10.0, biocoagulant dosage of 4.4 g L−1, and current density of 31.5 mA cm−2, which showed removals of turbidity and COD of 98.9 and 83.8%, respectively. [ABSTRACT FROM AUTHOR]

In this work, Lallemantia royleana seed mucilage (LRSM) was applied as a plant based coagulant in the initial stage of an integrated method for dye degradation. Photocatalytic ozonation (PCO) process was used under visible-light irradiation in the post-treatment stage. MnO2.MoS2 heterostructure nanocomposite was fabricated by hydrothermal synthesis and applied for the first time in PCO to mineralize Acid Blue 113 dye. The synthesized nanocatalyst was characterized by FT-IR, XRD, FE-SEM, TEM, DRS and BET. Characterization of the nanocatalyst showed that the composite consisted MoS2 with a sheet-like structure and MnO2 in the form of nanoparticles with different sizes in the range of 15–30 nm. By using the response surface methodology (RSM) approach, the best operational condition in the coagulation-flocculation (CF) stage has been acquired at pH 5.0, LRSM dose of 220 mg/L within 27 min. By applying the PCO process, complete decolorization has been attained using 11 mg of the catalyst and 0.2 g/L.h ozone dosage within 9 min. The use of LRSM along with MnO2.MoS2 nanocatalyst in the CF/PCO combined process for treating real wastewater samples indicates that the proposed technique is highly efficient and can be effectively employed to treat dye-containing industrial effluents. [ABSTRACT FROM AUTHOR]

In this study, coagulation combined with the electro-Fe0/H2O2 reaction was developed to treat refractory organics in the landfill leachate effluent of a membrane bioreactor (MBR), and the change in biodegradability was investigated. The results showed that polymerized ferric sulfate (PFS) was the best coagulant, with removal efficiencies of chemical oxygen demand (COD) and chromaticity of 74.18% and 72.22%, respectively, when the dosage was 2 g/L and the initial pH (pH0) was 6. Under the optimal conditions of pH0 of 3, current density of 5 mA/cm2, Fe0 dosage of 3 g/L, and H2O2 dosage of 0.059 M, the electro-Fe0/H2O2 reaction showed the removal efficiencies of COD and chromaticity for coagulated effluent were 76.68% and 74%, respectively. UV-vis and 3D-EEM spectral analysis showed that humic and fulvic acids were effectively degraded, and the effluent was mostly small molecules of aromatic protein-like substances. The whole process increased the BOD5/COD from 0.049 to 0.46, indicating that the biodegradability was substantially improved. This is due to the conjunction of the Fe0/H2O2 reaction with electrochemistry, which accelerated the reduction of Fe3+ to Fe2+ on the Fe0 surface and cathode and improved the efficiency of hydroxyl radical (•OH) generation, thus promoting the removal of pollutants. The operating cost was only 4.18 $/m3, with the benefits of less Fe0 loss and no pH adjustment. In summary, coagulation combined with the electro-Fe0/H2O2 reaction is a cost-effective method for treating refractory organics in leachate and enhancing biodegradability. [ABSTRACT FROM AUTHOR]

Using natural flocculants for water and wastewater treatment through coagulation-flocculation process has received growing attention due to its simplicity and safety process. In this research, the performance of pomegranate seed powder as a novel natural flocculant in treating pulp and paper wastewater (PPWW) was evaluated. Chemical oxygen demand (COD) reduction and turbidity removal from PPWW were monitored using different dosages of pomegranate seeds and alum salt. In addition, the synergistic effect of dual flocculation between pomegranate seeds and alum on PPWW treatment was investigated and optimized. Zeta potential (ZP), Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) analyses were conducted to elucidate the flocculation mechanism. The results revealed that pomegranate seeds composed of active substances such as protein, polysaccharides and fiber contents that contribute to its coagulating ability. The highest removal efficiencies of 60% and 87% were achieved for COD and turbidity, respectively when using pomegranate seeds at the optimal dosage of 600 mg/L after 30 min treatment. Dual flocculation of pomegranate seeds and alum showed a synergistic effect, resulting in a maximum removal of 81% of COD and 98% of turbidity under optimal condition: Alum = 400 mg/L and pomegranate seeds = 800 mg/L at much shorter treatment time (2 min). The ZP and FTIR test results and SEM images revealed that charge neutralization and sweeping mechanism induced by alum combined with bridging mechanism by pomegranate seeds led to the synergy. [Display omitted] [ABSTRACT FROM AUTHOR]

In this study, sequential coagulation and electro-oxidation (EO) processes were applied to landfill leachate, which is highly contaminated and complex wastewater. Since the pollutant content of the leachate was too high, the coagulation process (poly aluminum chloride (PAC) as a coagulant) was applied as a pre-treatment to reduce the cost of the EO process. The Box-Behnken design of response surface methodology was used. The color number (CN) removal efficiency estimated by the model under optimum operating conditions was 80.1%, while it was 77.6% in the experimental studies performed under optimum conditions to verify the model conformity. Multi-metal oxide doped Ti (MMO/Ti), Pt doped Ti (Pt/Ti), and graphite were used as anode and stainless steel was used as cathode in the EO process. In the EO process in which Pt/Ti anode was used, chemical oxygen demand (COD), UV254, and CN removal efficiencies were 52.8, 68.1, and 85.6%, respectively under the conditions of applied current 1.25 A and the pH 5. The CN value decreased to 4.2 after the coagulation process and it was 0.6 at the effluent of the EO process. [ABSTRACT FROM AUTHOR]

Commercial bakeries producing cakes, pies, cookies, biscuits, brownies, rolls, and a variety of other desserts generate wastewater with high loads of suspended solids, fats, oils, and grease (FOG) and high chemical oxygen demand (COD) and nutrients like ammonium nitrogen and nitrate-nitrogen which are too high for discharge to a municipal sewage system without pre-treatment. Due to the complex nature of this wastewater, it requires a multi-step solution. The objective of the present investigation is to perform a multiple-step treatability study of bakery wastewater such as chemical treatment using chemical coagulant, secondary treatment in anaerobic sequencing batch reactors (ASBR) with anaerobic bacteria, and finally aerobic treatment in a batch-fed reactor by the development of acclimatized seeds for both carbon oxidation and nitrification with subsequent study of the flow of chemical and microbiological processes in dynamics. A composite wastewater sample was collected from a nearby bakery plant located in Dhulagarh, West Bengal. After necessary characterization observed COD value was within a range of 4500 mg/L whereas ammonium nitrogen ( –N) and nitrate nitrogen ( –N) level was found in the range of 57 and 69 mg/L as N respectively. Simulated synthetic bakery wastewater was prepared in the laboratory. Chemical treatment was done using alum and polyelectrolyte to reduce mostly the organic materials present in the wastewater in the form of COD as the values of COD, –N, and –N were found within a range of 3000, 48, and 82 mg/L as N respectively after chemical treatment. For reduction of the residual high value of COD and nitrate nitrogen content of chemically treated real-life bakery wastewater anaerobic sequencing batch reactors (ASBR) were provided. Finally aerobic treatment was done for the final clarification of the wastewater. After three stage treatment process effluent wastewater become free from both organics and nutrients. [ABSTRACT FROM AUTHOR]

Nowadays, the treatment of mixed domestic–industrial wastewater has gained more attention, so, the main target of the study is to degrade the wastewater through a combination of primary, biological, and advanced oxidation processes. To enhance the treatment of the wastewater, the processes of coagulation, flocculation and sedimentation were applied before the biological treatment. The effect of the type and dose coagulants and effect of using polyacrylamide (PAM) as a coagulant aid were studied. The optimized conditions selected for the experiments were ferric chloride and alum. They showed a close treatment effectiveness since 400 mg/L was the best coagulant dose, and 10 mg/L was the best PAM dose. The chemical oxygen demand (COD), biological oxygen demand (BOD5), and total suspended solids (TSS) removal efficiencies were 58.8%, 55.9% and 67.5%, respectively at 10 mg/L PAM and 400 mg/L alum doses. When doses of ferric chloride and PAM were at 400 and 10 mg/L sequentially, the removal efficiency of COD, BOD5 and TSS were 61.8%, 59.7% and 71.1%, respectively. After the primary treatment, extended aeration was used for the biological wastewater treatment. The study aimed to evaluate the effect of hydraulic retention time (HRT) on the performance of the biological treatment via extended aeration. The removal rates at HRT of 24 h for COD, BOD5, TSS and total Kjeldahl nitrogen (TKN) were 70.6%, 86.2%, 58% and 70.7%, respectively. Increasing the HRT more than 24 h exerted a slight improvement in the pollutant removal efficiency. After the biological treatment, COD, BOD5, TSS and TKN in the effluent decreased, but the values did not meet the Egyptian standards. A Fenton process was provided in the treatment to ensure that the COD removal as stipulated by the regulations would be obtained in the final effluent. Different reaction conditions of Fenton treatment were examined, including H2O2 concentration and H2O2/Fe2+ ratios. The maximum removal was achieved at H2O2/ COD = 4.7. In addition, five different H2O2/Fe2+ molar ratios (20–160) were tested. COD removal percentage was 68.4% at the molar ratio of 160 and increased to 84.9% at the molar ratio of 40. [ABSTRACT FROM AUTHOR]

In addition to the large volume, the generated wastewater in paper and cardboard recycling industry contains various organic compounds and dyes. Treatment of these wastewaters is difficult due to the diversity of contaminants and the complexity of their chemical structure. This study aimed to investigate the efficiency of the coagulation and flocculation process by the new mixture of coagulants for wastewater treatment in one of the paper and cardboard recycling industries. To determine the efficiency of the coagulation and flocculation process in removing the parameters, including turbidity, colour, TSS, and COD, the Jar Test was used in laboratory conditions. By changing the variables, such as pH, coagulant type (PAC/MgCl2, PAC/Polymer, MgCl2/Polymer, MgCl2/PAC, PAC/MgCl2/Polymer), coagulant dose, and polymer dose, the optimal conditions were determined. Based on the results, the highest turbidity removal efficiency was achieved for the combination of coagulant and coagulant aid (PAC/MgCl2/Polymer) at pH 11. According to the experiments, the highest removal efficiency of turbidity, colour, COD and TSS were95.43%, 25.16%, 16.16%, and 83.33%, respectively. According to the obtained results, the coagulation and flocculation is a suitable method to remove turbidity and suspended solids in the paper and cardboard recycling industry wastewater. However, in order to remove more colour and COD, additional treatment is required. [ABSTRACT FROM AUTHOR]

Nejayote is a wastewater byproduct of traditional processes used to make corn tortilla flour, and needs to be treated to protect the environment. In this work, nejayote was treated by subjecting it to coagulation/flocculation and electrocoagulation processes. These two processes were evaluated independently and in combination. In the coagulation/flocculation process, the dose of coagulant/ flocculant and the influence of pH were determined. The electrocoagulation process was carried out using an Al/Fe (anode/cathode) system, and the effectiveness of the electrocoagulation as a function of pH and electrolysis time was studied. The control variables were the cell potential difference and NaCl concentration. The nejayote treatments was analyzed by measuring the resulting color, turbidity, and chemical oxygen demand (COD), and carrying out a UV-Vis analysis. The results showed that exclusive application of the electrocoagulation process to the nejayote was the most effective, having nearly completely eliminated color (99.4%), turbidity (98.08%) and COD (84.0%) after 150 min of electrolysis. The coagulation/flocculation process using the Sudflock P-63/Sumex Biofloc A-01 system was the least effective in reducing color (86.7%), turbidity (82.7%) and COD (34.2%), while the combined process (coagulation/flocculation–electrocoagulation), at a pH of 9.0 and 195 min of electrolysis, managed to remove 98.5% of the color, 97.7% of the turbidity and 78.0% of the COD. [ABSTRACT FROM AUTHOR]

Aquaculture effluent treatment is essential to eliminate the undesirable characteristics of water to ensure cleaner production and environmental sustainability. In an effort to develop green coagulant without compromising cost, this research investigated the feasibility of aquaculture effluent (AQEF) pollutant removal using Picralima nitida seeds extract (PNSC) and its bio-coagulation/adsorption kinetic characteristics with the substrate in water. The coagulative decrease was observed in terms of TD (turbidity), TSS (total suspended solids), COD (chemical oxygen demand), BOD (biochemical oxygen demand), and COLR (color) from AQEF. The active coagulant was extracted from the seeds and analyzed for its spectral and morphological characteristics through FTIR and SEM. The influence of PNSC dosage (0.10–0.50 g L−1), pH (2–10), settling time (0–60 min), and temperature (303–323 K) on the removal of contaminants were surveyed. The process kinetics of coagulation–flocculation were also explored. Maximal TD reduction of 90.35%, COD (82.11%), BOD (82.38%); TSS (88.84%), and COLR (65.77%) at 0.2 g PNSC L−1, pH 4, and 303 K was achieved. Analysis of variance (ANOVA) tests proved that pH, temperature, and settling time had a significant effect on pollutant removal. Results fitted Von Smoluchowski's perikinetics theory at the optimum conditions, which gave R2 > 0.900. At perikinetics circumstances, the Kb (reaction rate) and t f 1 2 (half-life) correspond to 0.0635 Lg−1 min−1 and 1.9 min. More so, sorption results fitted the Lagergren over the Ho model. Additionally, the net cost of using PNSC to handle 1 L of AQEF (including electricity, material, and labor costs) was evaluated to be €4.81. Overall, the PNSC appears reliable and useful in pretreating AQEF for improved biodegradability and superior effluent quality. [ABSTRACT FROM AUTHOR]

In this study, COD removal efficiencies were investigated in dairy industry wastewater by using variations of coagulation-flocculation and ozone oxidation in laboratory. Coagulationflocculation (CF), ozonation (O), ozonation following coagulation-flocculation (CF+O) and coagulation-flocculation following ozonation (O+CF) processes were applied to the wastewater. Optimum pH and optimum dosages were studied at various pH values and at various coagulant doses at room temperature (25oC). In ozone oxidation, wastewater was taken to ozonation reactor and ozone was given 1 g/hour dose and COD removal efficiencies were determined by taking samples in 15, 30, 45, 60, 90, 150, 210 and 240 minutes. Treatment performance of coagulation and flocculation and ozonation processes and their variations were evaluated by COD removal efficiencies. The optimum pHs for the Al2(SO4)3 and FeCl3 were found as 7 and 6 respectively. The optimum dosages were 1200 mg/L for Al2(SO4)3 and 500 mg/L for FeCl3. At optimum conditions, approximately 45% and 28% of COD were removed by using FeCl3 and Al2(SO4)3 respectively. When only ozonation was applied, COD removal efficiency was determined as 20% at the end of 240 minutes. COD removal efficiency was 65% with the application of ozonation after coagulation-flocculation (CF+O). When the coagulation-flocculation process was applied after the ozonation process (O+CF), COD removal efficiency remained at 52%. [ABSTRACT FROM AUTHOR]

[Display omitted] In this study, bauxite tailings were innovatively employed as the coagulant resource in the treatment of nanofiltration concentrated landfill leachate (NCLL) via bipolar membrane electrodialysis (BMED). The employment of H 2 C 2 O 4 as the leaching acid, in lieu of HNO 3 , not only promoted the leaching of metal ions but also minimized the competitive migration of free H+, attributable to its chelating effect. The COD removal increased from about 40.4 % to about 49.9 %, while the energy consumption (EC) decreased to about 0.05 kWh/g COD when the acid is replaced by H 2 C 2 O 4. An optimal dosage of bauxite tailing is crucial for effective COD removal. An increase in the initial concentration of H 2 C 2 O 4 benefits metal leaching, while, an excessive concentration thereof augments the competition of H+ ions, thereby impeding the coagulation process. Furthermore, the current density exerted a notable impact on both COD removal and EC, with an optimal density identified at 5 mA/cm2. Connecting more treatment units still maintains COD removal efficiency at approximately 50 %, with a significant reduction in EC of about 24 %, necessitating only 0.038 kWh/g COD. Humic-like and fulvic-like acids are efficiently coagulated, which represent the principal biorefractory substances in NCLL. Consequently, this research delineates a novel approach for the utilization of bauxite tailings and the treatment of NCLL. [ABSTRACT FROM AUTHOR]

Two coagulants (Al2(SO4)3 and FeSO4) were investigated for their performance in treating raw and anaerobic effluents from a palm oil mill. The treatment efficiencies for both palm oil mill effluents (POMEs) were assessed based on chemical oxygen demand (COD) removal. Different dosages of Al2(SO4)3 and FeSO4 were investigated in terms of COD removal in raw and anaerobic effluents under different pH levels. The results show that FeSO4 performed better than Al2(SO4)3 in removing COD from both effluents. The maximum COD removal efficiency (94%) was achieved when both effluents were treated with 0.4 g of FeSO4 at pH 3, while the maximum COD removal achieved by Al2(SO4)3 was 70% using 0.4 g at pH 7. Using these optimal operational conditions, the removal of 11 parameters, namely COD, color, total suspended solids (TSS), electrical conductivity, biochemical oxygen demand (BOD), pH, NH3-N, Cu+2, Fe+2, Zn+2, and Pb were measured and assessed. The results were analyzed statistically using factor analysis (FA) and cluster analysis (CA) to identify the main factors responsible for the differences in the parameters and to display the similarity and dissimilarity between the selected parameters among the different POME sources. The FA method produced four factors responsible for more than 99% of the differences in data. The first factor covered COD, color, TSS, and BOD and was responsible for explaining 36% of the differences, whereas the second factor was responsible for explaining 34% of the differences, including NH3-N, Cu+2, Fe+2, and Zn+2. The percentage variance explained by the third and fourth factors was 16% and 14%, respectively. The CA method produced three different groups (clusters). It was found that raw and anaerobic POMEs treated with Al+3 and raw POMEs treated with Fe+2 were close to each other, representing the second cluster, while the raw treatment represented the first cluster. The last cluster represents the anaerobic effluent before and after coagulation using Fe2SO4. The results reveal that Fe2SO4 is an efficient method for removing organic and heavy metal content from POME. The study provides essential data and knowledge that can be used to evaluate and manage POME treatment. [ABSTRACT FROM AUTHOR]

BACKGROUND: Efficient pretreatment is key to improving landfill leachate biodegradability. This is the first study to combine hydrodynamic cavitation (HC) and potassium ferrate (K2FeO4) for the treatment of landfill leachate, using chemical oxygen demand (COD) and UV absorbance at a wavelength of 254 nm (UV254) as the main test indicators. The feasibility of HC combined with K2FeO4 as a mature leachate pretreatment method was explored. RESULTS: The HC experiment used 40 L of mature landfill leachate raw water, with optimal reaction conditions of: pH 4, 70 min continuous cavitation and K2FeO4 dosage of 1.5 g/L. The leachate COD decreased from 3812.64 mg/L to 1833.8 mg/L (51.69% removal), while UV254 decreased from 20.44 to 6.14 (65.14% removal) and total organic carbon decreased from 1489 to 915.3 mg/L (38.53% removal). After HC/K2FeO4 treatment, the biochemical oxygen demand after 5 days (BOD5)/COD (0.61) was greatly improved compared to the raw leachate (0.362), with effluent reaching the standard (BOD5/COD >0.6) required to be considered fully biodegradable. Studies have shown that HC can accelerate the reaction rate of Fe(VI) with pollutants, while also forming a Fenton‐like system with the products of Fe(VI) reduction. FT‐IR analysis results showed that HC/K2FeO4 treatment achieved the removal of complex high molecular weight compounds, by carbonization or decomposition into more biodegradable substances. CONCLUSION: Compared with the traditional pretreatment process, HC/K2FeO4 exhibits strong oxidation and coagulation performance, achieving the significant removal of leachate humus and effectively improving biodegradability, while also being suitable for large‐scale applications, such as landfill leachate treatment. © 2022 Society of Chemical Industry (SCI). [ABSTRACT FROM AUTHOR]

Utilization of pinecone powder as a plant-based natural coagulant for the treatment of iron and steel factory effluent was examined. The concentrations of chemical oxygen demand (COD), total suspended solids (TSS), ammonia-nitrogen (NH3 –N), manganese (Mn), iron (Fe), zinc (Zn), aluminum (Al), and nickel (Ni) in effluent wastewater were investigated. Results showed that the maximal removal of COD, TSS, NH3 –N, Mn, Fe, Zn, Al, and Ni using pinecone powder were 83.3%, 99%, 83.9%, 86.8%, 93.7%, 89.7%, 73.7%, and 86.7%, respectively for effluent at natural pH 8 using a dosage of 3 g/L. The Fourier-transform infrared spectroscopy result showed the existence of various functional groups involved in the coagulation process. Overall, this study shows that pinecone powder has enormous promise as a natural coagulant for water treatment and it could be utilized to treat effluent from iron and steel plants. [ABSTRACT FROM AUTHOR]

An evaluation of a laboratory scale chemical coagulation using aluminium chlorohydrate (1%) and polyamine (1%) coagulants on its effectiveness in the removal of bulk inert pollutant contents such as particulate chemical oxygen demand (COD) and turbidity to obtain clean effluent discharge and most cost-effectively treated effluent using a jar test was conducted in this current study. This study aimed to find the viable inert removal coagulant between the two above-mentioned coagulants in order to achieve zero liquid effluent discharge (ZLED). The preliminary results showed that adding variable dosages of polyamine and 50% aluminium chlorohydrate combined coagulants dosages presented an improved particulate chemical oxygen demand, color, and turbidity removal efficiencies. The ascertained turbidity removal efficiency using the combined coagulation dosage of polyamine–aluminium chlorohydrate (PAC) treatment was 90.50% and 59.36% particulate chemcial oxygen demand removal, as comparable to polyamine alone with particulate chemical oxygen demand removal of 50% and turbidity of 75%. Likewise, an appreciable removal efficacy was observed as the aluminium chlorohydrate treatment alone was for particulate chemical oxygen demand and turbidity was 37% and 54%, respectively. In essence, this study emphasized the knowledge gap of the significant effect of the polymeric polyamine flocculant strength in adopting the combined coagulation dosage method to improve its coagulation efficiency and the high agglomeration on suspended solids, thereby, removing more of the unwanted inert contents from brewery wastewater. To determine zero liquid effluent discharge, this study clearly recommended an integrated treatment approach, microbial fuel cell integrated with a lab scale chemical coagulation technique for efficient non-biodegradable pollutant removal. [ABSTRACT FROM AUTHOR]

The effects of initial total phosphorus (TP) concentration, current density, conductivity and initial pH value on the removal rate of TP and energy consumption, as well as the behaviour and mechanism of phosphorus removal, were investigated by sinusoidal alternating current coagulation (SACC). The flocs produced by SACC were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy FTIR and X-ray photo electron spectroscopy. The thermodynamic and kinetic behaviours of phosphorus removal by iron sol adsorption were also studied in detail. In a self-made SACC reactor equipped with five sets of parallel iron electrodes spacing 10 mm, the removal rate of TP reached 90.9% for a pH 7.0 wastewater with 5 mg dm−3 TP (κ = 800 μS cm−1) after being treated for 60 min by applying 2.12 mA cm−2 sinusoidal alternating current. Compared with direct current coagulation (DCC), SACC exhibits a higher removal efficiency of phosphorus due to the stronger adsorption of the produced flocs. It was found that the adsorption in the SACC process follows pseudo-second-order kinetic with the involvement of the intra-particle model. The adsorption of iron sol to phosphorus was an endothermic and spontaneous process, and its adsorption behaviour can be characterized with Langmuir and Redlich–Peterson isothermal adsorption models. SACC may be employed for the treatment of more complex wastewater combined with biological and/or electrochemical techniques. [ABSTRACT FROM AUTHOR]

This study examines the integrated electro-coagulation–electro-oxidation (EC–EO) process as an alternative for the treatment of an industrial effluent originating from a soluble coffee production. Experiments were carried out in a laboratory-scale batch cell reactor. Monopolar configuration of electrodes was employed (EC: anode: iron and cathode: stainless steel; EO: anode: boron-doped diamond-Si and cathode: stainless steel), operating in galvanostatic mode. The effect of main operation parameters on decolorization, chemical oxygen demand (COD) and total organic carbon (TOC) degradation and total operation costs was studied. The experimental design, analysis of variance, response surface methodology and constrained optimization algorithms let to establish the most effective operation conditions as follows: for EC (support electrolyte = 4.32 g of Na2SO4/L; current density (J) = 150 A/m2; gap between electrodes = 3 mm; stirring velocity = 350 RPM; electrolysis time (t) = 60 min; and EC's initial pH (pHi, EC) = 4.71 (the pH of raw wastewater)); and for EO (J = 300 A/m2; t = 100 min; gap between electrodes = 3 mm; stirring velocity = 125 RPM; and pHi, EO = 7.0). The integrated EC–EO process let to accomplish ca. 98% decolorization, ca. 73% of both COD and TOC removal, more oxidized (Average Oxidation State = 0.149), biocompatible (BOD5/COD ratio = 0.404) and less toxic effluent (median lethal concentration of an analyte which causes 50% population death, LC50 lower than 126.43 ppm of raw wastewater), generating 3.782 g/L of sludge, with total operation costs of 8.43 USD/m3. During EC, contaminants with molecular weight (MW) higher than 30 kDa were effectively decomposed. The integrated EO process additionally let to break down pollutants with MW in the range of 5 to 10 kDa. The EC–EO total operation time of 160 min. was required to meet Colombian permissible discharge limits. [ABSTRACT FROM AUTHOR]

Wastewater from olive oil mills (OMW) represents a major environmental problem that requires effective treatment to decrease pollution. In the present work, the treatment of olive oil mill wastewater by coagulation was studied using Moringa Oliefera as a natural coagulant. The processing is optimized using both Design of Experiments (DOE) methodology and a central composite design (CCD) combined with the response surface methodology (RSM). The optimization describes the relationship between 3 responses (turbidity, COD, and polyphenols) and 4 independent variables (Moringa Oliefera concentration, pH, agitation speed, and time). Analysis of variance ANOVA using Fisher's test indicated that the established models were significant. The study showed that the model was characterized by a good fit, justified by the very high adjusted coefficient of determination (R2Adj = 86.73%, R2Adj = 90.39% and R2Adj = 93.33% for the turbidity, COD, and polyphenols, respectively). Furthermore, the optimum conditions for a good purification performance of OMW using Moringa Oliefera are as follows [Mo] = Moringa Oliefera = 65 g/L, pH = 6, Agitation speed (Ss) = 35 rpm and Agitation time (St) = 25 min. Under these conditions, the turbidity, COD and polyphenol removal efficiencies are 96%, 88%, and 86% respectively. Finally, the proposed treatment process is a critical development in sustainable environmental technologies. [ABSTRACT FROM AUTHOR]

[Display omitted] • Cake layer formed in C-UF dominated reversible fouling and notably affected irreversible fouling. • Residual HA in coagulation effluent also played an important role on irreversible fouling. • Cake layer could be used as dynamic membrane to remove HA and alleviate membrane fouling before UF. • Cake layer mainly removed HA with larger MW by physical adsorption or interception on the upside. • Hydrophilic cake layer formed by compact flocs with positive charge could better remove HA. Cake layer is considered to play a crucial role in membrane fouling during the coagulation-ultrafiltration process. However, the contribution of the cake layer on membrane fouling and probable natural organic matter (NOM) removal in this process is unclear, leading to a limited understanding of cake layer and potential secondary utilization. Here, ultrafiltration (UF) membrane fouling contribution, NOM removal, and dynamic membrane application of the cake layer were investigated. Results showed reversible fouling was dominated by cake layer, whereas irreversible fouling was determined by both cake layer and residual NOM in coagulation effluent. Compared with direct UF, the cake layer improved approximately by 15 % of HA removal with molecular weight (MW) of 2000–4000 Da. By optimizing membrane material, HA removal and membrane fouling alleviation were synchronously achieved by cake layer deposition-UF. According to mechanisms analysis, HA removal was attributed to the adsorption or interception of HA with larger MW by the cake layer. Zeta potential and fractal dimension of flocs, and contact angle of the cake layer were closely related to HA removal by cake layer, whereas reversible and irreversible fouling were positively correlated with cake layer thickness and floc fractal dimension respectively. Compared with other dynamic membranes, the cake layer had the best economic performance, which provided application potential on NOM removal in micro-polluted surface water. [ABSTRACT FROM AUTHOR]

The deep removal of organic pollutants is challenging for coagulation technology in drinking water and wastewater treatment plants to satisfy the rising water standards. Iron (III) chloride (FeCl 3) is a popular inorganic coagulant; although it has good performance in removing the turbidity (TB) in water at an alkaline medium, it cannot remove dissolved pollutants and natural organic matter such as humic acid water solution. Additionally, its hygroscopic nature complicates determining the optimal dosage for effective coagulation. Biochar (BC), a popular adsorbent with abundant functional groups, porous structure, and relatively high surface area, can adsorb adsorbates from water matrices. Therefore, combining BC with FeCl 3 presents a potential solution to address the challenges associated with iron chloride. Consequently, this study focused on preparing and characterizing a novel biochar/ferric chloride-based coagulant (BC–FeCl 3) for efficient removal of turbidity (TB) and natural organic matter, specifically humic acid (HA), from synthetic wastewater. The potential solution for the disposal of produced sludge was achieved by its recovering and recycling, then used in adsorption of HA from aqueous solution. The novel coagulant presented high TB and HA removal within 10 min of settling period at pH solution of 7.5. Furthermore, the recovered sludge presented a good performance in the adsorption of HA from aqueous solution. Adsorption isotherm and kinetics studies revealed that the Pseudo-second-order model best described kinetic adsorption, while the Freundlich model dominated the adsorption isotherm. • A novel biochar/ferric chloride composite coagulant-adsorbent was synthesized. • FeCl 3 's hygroscopic issue resolved; optimal coagulation dosage determined effectively. • The coagulation with 10 min of settling time at near-neutral pH solution was achieved. • A remedial approach for mitigating sludge-borne iron contamination is proffered. • The recovered sludge presented a good performance in the adsorption of HA. [ABSTRACT FROM AUTHOR]

Chemical coagulation has gained recognition as an effective technique to enhance the removal efficiency of pollutants in wastewater prior to their entry into a constructed wetland (CW) system. However, its potential impact on the chemical and microbial properties of soil and plant systems within CWs requires further research. This study investigated the impact of using ferric chloride (FeCl 3) as a pre-treatment stage for dairy wastewater (DWW) on the chemical and microbial properties of water-soil-plant systems of replicated pilot-scale CWs, comparing them to CWs treating untreated DWW. CWs treating amended DWW had better performance than CWs treating raw DWW for all water quality parameters (COD, TSS, TP, and TN), ensuring compliance with the EU wastewater discharge directives. Soil properties remained mostly unaffected except for pH, calcium and phosphorus (P), which were lower in CWs treating amended DWW. As a result of lower nitrogen (N) and P loads, the plants in CWs receiving FeCl 3 -amended DWW had lower N and P contents than the plants of raw DWW CWs. However, the lower loads of P into amended DWW CWs did not limit the growth of Phragmites australis, which were able to accumulate trace elements higher than CWs receiving raw DWW. Alpha and Beta-diversity analysis revealed minor differences in community richness and composition between both treatments, with only 3.7% (34 genera) showed significant disparities. Overall, the application of chemical coagulation produced superior effluent quality without affecting the properties of soil and plant of CWs or altering the functioning of the microbial community. [Display omitted] • Wastewater pre-treatment using FeCl 3 improved the performance of CWs. • FeCl 3 pre-treatment had no negative effects on soil and plant properties. • FeCl 3 pre-treatment did not alter microbial community diversity and composition. [ABSTRACT FROM AUTHOR]

Considering the limited literature and the difficulty of quantifying 1-μm micro-nanoplastics (1-μm MNP) in complex aqueous matrices such as wastewater and sludge, the removal rate of these very small particles in wastewater treatment plants (WWTP) represents a major challenge. In this study, coagulation-flocculation-sedimentation (CFS) with aluminum salts was investigated to evaluate the removal of 1-μm MNPs spiked in tap water, raw wastewater, pre-settled wastewater, and activated sludge. Quantification of 1-μm MNP was performed using the high-throughput flow cytometry (FCM) analysis which takes only a few minutes and produces results with high accuracy and reproducibly. The results indicated that the 1-μm MNPs were highly stable in pure water and unable to settle rapidly. In raw wastewater, sedimentation without coagulants removed less than 4% of 1-μm MNP. Conversely, CFS treatment showed a significant improvement in the removal of 1-μm MNP from wastewater. At dosages of 0.3–3 mg Al3+/L, the removal of MNPs in wastewater reached 30% and no flocs were observed, while floc formation was visible with increased dosages of 3–12 mg Al3+/L, obtaining MNP removal greater than 90%. CFS in activated sludge with a solids content of 5800 mg MLSS/L registered the highest removal efficiency (95–99%) even for dosages of 0.3–60 mg Al3+/L and pH dropping to 5. However, activated sludge showed extremely high removal efficiency of MNPs (97.3 ± 0.9%) even without coagulants. The large, dense flocs that constitute activated sludge appear particularly efficient in capturing 1-μm MNPs during the sedimentation process even in the absence of coagulants. [Display omitted] • High-throughput flow cytometry to enumerate 1-μm microplastics in few minutes. • Coagulation-flocculation to investigate microplastics removal from wastewater and sludge. • 1-μm microplastics in wastewater are removed by 30% with 0.3–3 mgAl3+/L. • 1-μm microplastics in activated sludge are removed by 99% with 0.3–3 mgAl3+/L. • Activated sludge showed removal of 1-μm plastics of 97% even without coagulants. [ABSTRACT FROM AUTHOR]

While the effectiveness of Poly-Aluminum Chloride (PAC) coagulation for pollutant removal has been documented across various wastewater scenarios, its specific application in hospital wastewater (HWW) treatment to remove conventional pollutants and hazardous genetic pollutants has not been studied. The research compared three hospital wastewater treatment plants (HWTPs) to address a knowledge gap, including the PAC coagulation-sodium hypochlorite disinfection process (PAC-HWTP), the biological contact oxidation-precipitation-sodium hypochlorite process (BCO-HWTP), and a system using outdated equipment with PAC coagulation (ODE-PAC-HWTP). Effluent compliance with national discharge standards is assessed, with BCO-HWTP meeting standards for direct or indirect discharge into natural aquatic environments. ODE-PAC-HWTP exceeds pretreatment standards for COD and BOD5 concentrations. PAC-HWTP effluent largely adheres to national pretreatment standards, enabling release into municipal sewers for further treatment. Metagenomic analysis reveals that PAC-HWTP exhibits higher removal efficiencies for antibiotic resistance genes, metal resistance genes, mobile genetic elements, and pathogens compared to BCO-HWTP and ODE-PAC-HWTP, achieving average removal rates of 45.13%, 57.54%, 80.61%, and 72.17%, respectively. These results suggests that when discharging treated HWW into municipal sewers for further processing, the use of PAC coagulation process is more feasible and cost-effective compared to BCO technologies. The analysis emphasizes the urgent need to upgrade outdated equipment HWTPs. [Display omitted] • PAC-HWTP better removes genetic contaminants than BCO-HWTP, ODE-PAC-HWTP. • PAC-HWTP is cost-effective, meeting pretreatment norms for sewer release. • Urgent upgrades for outdated HWTPs needed to boost pollutant removal efficiency. • Metal resistance, mobile genetic elements, microbes determine antibiotic resistome. [ABSTRACT FROM AUTHOR]

Haoud Berkaoui is one of the most important oil-producing regions in Algeria. It covers three productive fields namely: Haoud Berkaoui, Guellala and Benkahla. Haoud Berkaoui's production center operations generate daily significant amounts of oily wastewater contaminated with hydrocarbons and suspended matters. At this field is set at each production center a deoiling station to ensure both hydrocarbons recovery and the production of reinjection water. These stations use three conventional techniques for oily wastewater treatment, namely: coagulation, flocculation and sedimentation. In order to improve the efficiency of the implemented process, three new coagulants were developed and tested. For settling period set at 30 min, dosage effects of coagulants ranging from 8 to 40 mL/L of treated oily wastewater were studied for turbidity elimination, suspended matter and hydrocarbons. The use of the coagulant composed of 4% sodium silicate and 1.4% sulfuric acid at a rate of 40 mL/L of treated oily wastewater gave the best results in terms of treatment by ensuring pH normalization, suspended matter; elimination of turbidity and reduction of hydrocarbons content by 81%. [ABSTRACT FROM AUTHOR]

Mining industry uses and returns into the environment great quantities of water resulted both during coal mining and processing. The most important water polluting sources are the coal processing plants. This fact imposes the existence of a complex water circulation process. The reagents used by coal mining industry for waste water cleaning may be divided in three classes: electrolytes or chemical salts; natural polymers and synthetic polymers. Because the waste water quality exceeds the legal limits and the tested reagents regimes did not prove their efficiency this study analyses separately the two processes involved in water cleaning: coagulation and flocculation using trivalent electrolytes: ferric chloride and aluminum sulphate. [ABSTRACT FROM AUTHOR]

[Display omitted] • The optimal Fe(II)/PMS dosage achieves a 99% alkali lignin removal rate. • Oxidation and coagulation collaborate for effective alkali lignin removal. • Alkali lignin may induce the transition from Fe(III) to Fe(II) • Redox-reaction enhanced degradation and coagulation of alkali lignin. In this work, Fe(II)/Peroxymonosulfate (PMS) treatment with dual functionality of pre-oxidation and coagulation was applied to enhance the removal of alkali lignin in water. The removal efficiency of alkali lignin (2 g/L) could reach ∼ 99% at an optimal dosage of [Fe(II)] = 2.4 mM and [PMS] = 7.8 mM, which was efficiently superior than that using ferric and polymeric coagulant individually. Pre-oxidation, involving hydroxyl radical (•OH) and sulfate radical (SO 4 •−), has been demonstrated to play a crucial role in both oxidative degradation (∼30%) and reducing the molecular weight and hydrophilicity of lignin. Meanwhile, the formation of polynuclear Fe-hydroxide complexes was also fostered, which in turn greatly contribute to the removal of lignin through an enhanced coagulation mechanism. The reductive units present in alkali lignin was demonstrated to initiate a dynamic transition between Fe(III) and Fe(II) by donating electrons. This redox activity is anticipated to continuously promote the formation of electro-neutral and loose flocs, thereby resulting in an enhanced coagulation performance. Furthermore, ultrafiltration (UF) was also demonstrated as a viable liquid/solid separation method following Fe(II)/PMS treatment, effectively promoting membrane flux recovery rate to ∼90%. This highlights the remarkable potential of this method when combined with other treatment processes. This study aims to offer a complementary strategy for remediating alkali lignin wastewater while advancing the fundamental understanding of redox-reaction enhanced in-situ coagulation in water treatment applications. [ABSTRACT FROM AUTHOR]

• An electrocoagulation system was built to separate emulsified metal cutting fluid from water. • Both pH and metal cutting fluid removal increased with time following an exponential behavior. • The effect of drilling holes in the electrodes was studied. • Removal of 90% of the metal cutting fluid was achieved. • Removal efficiency can be increased if the electrodes are perforated. A continuous electrocoagulation reactor with electrode polarity switch was used for removal of a metalworking fluid from synthetic oily water. The effects of perforating the aluminum electrodes, changing the number of holes, flow rate and the distance between electrodes were studied. Higher values of flow rate reduced final pH. Perforating the electrodes led to faster convergence of pH to its maximum value with no measurable increase in mass loss. If the distance between electrodes is also increased, there is an improvement in efficiency. With 10 holes, adjusting flow rate and inter-electrode distance, 90.2 ± 0.3% oil removal was achieved with a final pH of 8.83, which is within limits allowed by legislation. [ABSTRACT FROM AUTHOR]

Raw real silk textile wastewater was treated using batch electrochemical coagulation (ECC) method. Iron and aluminum electrodes in monopolar parallel arrangement were using a specific electrode area to volume of 24 m²/m³ and a cell voltage of 6 V as the optimal operating condition. Chemical oxygen demand removal ranged from 88% to 92% for iron and aluminum electrodes. Settleability and filterability characteristics of ECC-treated wastewater were at ease. UV–visible spectral analysis was carried out to evaluate the efficiency of ECC treatment for color removal from textile wastewater. An electrolysis time of 10–20 min was sufficient to remove maximum apparent color from the solution. The sludge obtained after electrochemical treatment (ECT) was analyzed for its composition by energy-dispersive spectroscopy. The supernatant from ECT after sludge settling was further treated using membrane bioreactor (MBR) for removal of trace pollutants/solids residues. The results proved the suitability of the dual hybrid treatment process for the complete removal of pollutants/contaminants combining ECC and MBR with ~75% clear water reclamation. [ABSTRACT FROM AUTHOR]

Highlights • Industrial container and drum cleaning (ICDC) wastewater characterization was done. • The concentrations of pollutants in ICDC wastewater have very variable structure. • Fenton-like process and combined coagulation/oxidation processes have been studied. • All methods were suitable for the removal of COD, BOD, TOC, TP, and of some metals. • Fenton-like process is a favorable system for modification of existing system. Abstract Industrial container and drum cleaning (ICDC) facilities generated complex wastewater which have organic/inorganic compounds, acids, alkalis, metals, dyes, asbestos, PCBs, chemical cleaning solutions or textile auxiliary chemicals. Treatment of such these wastewaters containing all these pollutants is also very difficult. It is required that the wastewater chemical oxygen demand (COD) is below 1500 mg/L to treat in a centralized wastewater treatment facility in Thrace Region, Turkey. In this study the characterization of ICDC industrial wastewater and treatment alternatives of this wastewater using Fenton-like (FL) process, acidic coagulation-flocculation + H 2 O 2 /UV-C (CF + H 2 O 2 /UV-C) and acidic coagulation-flocculation + S 2 O 8 2− (CF + S 2 O 8 2−) processes have been studied. The existing treatment system already has a biological treatment system after coagulation-flocculation system and couldn't be operated effectively in spite of all the efforts. We have studied processes that can be integrated into the coagulation-flocculation (CF) process used in the existing wastewater treatment plant. According to characterization study, COD values were in the range of 4584–18125 mg/L. The COD of the wastewater used in treatment experiments were 11,853 mg/L. According to the results FL and CF + S 2 O 8 2− systems were suitable for the COD discharge standards specified for the centralized wastewater treatment plant. The optimum conditions of FL process were 0.8 g/L for FeCl 3 and 45 g/L for H 2 O 2 and COD was measured as about 1500 mg/L at these doses. The optimum conditions of CF + S 2 O 8 2− system were determined as 0.64 g/L FeCl 3 for CF and 15 g/L H 2 O 2 doses. At these dosages the highest COD removal efficiency was achieved to 68% after 5 h. All methods used were suitable for the removal of COD, biochemical oxygen demand (BOD), total organic carbon (TOC), total phosphorus (TP) and of some metals. Considering the integration into the existing treatment system and applicability, it is concluded that the FL process is most favorable. [ABSTRACT FROM AUTHOR]

In this study is present the advantages and disadvantages of the use of different type of coagulants and flocculants for industrial wastewater treatment. This paper details how to survey and select appropriate reagents permit resolve of many problems appear in wastewater treatment. It is designed to be used as a study to learn about the operation of flocculation-coagulation process. The industrial wastewater can be regards as black box where mechanical operational-chemical operation are interconnected. Troubleshooting problems in primary system have direct influence over secondary systems (heavy metal removal, emulsion breaking, sludge thickening, dewatering etc.). To reduce the harmful effects that wastewater can produce, some form of treatment is necessary environmentally friendly, with minimize energy consumption. The relationship between water and energy and necessity for better managing energy consumption continues to have a great attention in raw water and wastewater treatment plants. The use of electricity and different reagents for water and wastewater treatment, impose unitary analysis. Appling unitary practice, function of the kind of wastewater treatment plant, will be possible to adopt the best solution considering all processes that concur to obtain a clean water. The aim of this study was analysis of characteristics of flocculants and coagulants, that can be used in wastewater treatment, for establish the application conditions. [ABSTRACT FROM AUTHOR]

The extreme pH, high color, and poor biodegradability of refractory wastewater have severe impacts on its biological treatment. To address this issue, an advanced Fe-Cu process with redox reaction and spontaneous coagulation was investigated and applied for pilot-scale (wastewater flow rate of 2000 m3·day−1) pretreatment of separately discharged acidic chemicals and alkaline dyeing wastewater. The advanced Fe-Cu process had five functions: (1) increasing the pH of chemical wastewater to 5.0 and above, with an influent pH of approximately 2.0; (2) transforming refractory organics of chemical wastewater with 10.0% chemical oxygen demand (COD) and 30.8% color removal, thereby enhancing the ratio of biological oxygen demand after five days (BOD 5) to COD (B/C) from 0.21 to 0.38; (3) neutralizing the pH of the pretreated chemical wastewater for coagulation application with alkaline dyeing wastewater to avoid adding alkaline chemical; (4) achieving average nascent Fe(II) concentrations of 925.6 mg∙L−1 using Fe-Cu internal electrolysis for mixed wastewater coagulation, resulting in an average of 70.3% color removal and 49.5% COD removal; (5) providing more efficient COD removal and B/C enhancement than FeSO 4 ∙7 H 2 O coagulation while avoiding secondary pollution. The green process offers an effective, easy-implemented solution for the pretreatment of separately discharged acidic and alkaline refractory wastewater. [Display omitted] • The advanced Fe-Cu process includes bimetal redox reaction and spontaneous coagulation. • The acid chemical and alkaline dyeing wastewater were simultaneously pretreated by pH adjustment and detoxification. • Compared with traditional pretreatment, this more low-cost process realizes a superior effect. • The pilot-scale study with wastewater flow rate of 2000 m3·day−1 was operated continuously for 24 weeks. • After the actual operation, this process is proved to be worthy of wide application. [ABSTRACT FROM AUTHOR]