Chemical Coagulation Research Articles

Comparative Study on the Effectiveness of Poly Aluminium Chloride (PAC), Aluminium Sulfate, and Iron Sulfate in Livestock Wastewater Treatment

This study investigates the effectiveness of chemical coagulation methods for treating livestock wastewater, a significant environmental concern due to the high levels of organic and inorganic pollutants it contains. The coagulants employed in this research include Poly Aluminium Chloride (PAC), Aluminum Sulfate (Al₂(SO₄)₃·18H₂O), and Iron Sulfate (FeSO₄·7H₂O). Experimental results demonstrate that the treatment with PAC achieved the highest reduction in Chemical Oxygen Demand (COD), with values decreasing from an initial concentration of 1431.32 mg/L to 700.18 mg/L, corresponding to a removal efficiency of 77.38%. Similarly, Biochemical Oxygen Demand (BOD₅) values decreased from 1734.43 mg/L to 417.33 mg/L, achieving a removal efficiency of 75.68%. The Total Suspended Solids (TSS) also showed a significant reduction, reaching 112.02 mg/L after treatment, well below the regulatory limit of 150 mg/L as stipulated by QCVN 62-MT:2016/BTNMT. While Aluminum Sulfate and Iron Sulfate demonstrated some level of effectiveness, their results did not meet the regulatory standards, with residual COD, BOD₅, and TSS concentrations remaining above permissible limits. This study concludes that PAC is the most effective coagulant for livestock wastewater treatment, suggesting further optimization and potential application in agricultural settings to mitigate the environmental impact of livestock operations.

Comparative treatment of textile dye wastewater with chemical coagulants and bacterial exopolysaccharides

Traces of chemical coagulants, such as alum, commonly used in wastewater treatment, remain in the water effluent and also result in secondary sludge that is difficult to treat. On the other hand, Extracellular Polymeric Substances (EPS) are safer and can be used as alternative bio flocculants. A study was hence done to compare the effectiveness of the treatment of Reactive Black 5 (RB5) textile wastewater with chemical coagulants and bacterial EPS. The jar test method was used to treat the wastewater with Alum and Polyferrous Sulphate (PFS) at varied pH (2–10) and respective dose concentrations. EPS was produced by bacteria isolated from cotton gin trash soil collected from Kitui ginnery in Kenya. EPS treatment was done at 30 °C for 72 h. EPS-producing bacteria isolates were identified by molecular analysis. The chemically and EPS-treated wastewater was analyzed for color, Total Dissolved Solids (TDS), and Chemical Oxygen Demand (COD). Respective color and TDS removal capacity by PFS and alum were (86.1% and 42.18%) and (85.1% and 69%) at their optimal conditions of (pH 7 and 100 mg/L) and (pH 7 and 140 mg/L). Similarly, PFS and alum reduced COD by 27.25% and 26.65%. Respective dye removal by YEAK2 −5 and YEPD K2 −2 EPS was 69.1% and 85.7%. However, YEPD K2 −2 and YEAK2 −5 EPS caused a respective rise of TDS by 40.14% and 67.17%. The respective reduction of COD by YEPD K2 −2 and YEAK2 −5 EPS was 56.25% and 54.24%. The chemically and EPS-treated wastewater met the National Environment Management Authority (NEMA) limits. The YEPD K2 −2 and YEAK2 −5 isolates were both identified as Bacillus sp. GC–MS and FTIR analysis results indicated that the two EPS were heteropolysaccharides composed of different sugar derivatives and hydroxyl as the main functional group. The results for treatment of the dye wastewater by Alum, PFS, and EPS were therefore comparable. The bacterial EPS bio flocculants can therefore serve as effective and cleaner substitutes to the alum and PFS chemical coagulants.

Study of Leachate Characteristics and Effectiveness of Chemical Coagulation and Electro-Oxidation for Leachate Landfill Pre-Treatment

Study of Leachate Characteristics and Effectiveness of Chemical Coagulation and Electro-Oxidation for Leachate Landfill Pre-Treatment

Application of Thymus Species as Natural Coagulant for Elimination of Turbidity of Water and Its Comparison with the Conventional Coagulant

Introduction: The most important pollutant in surface water sources is turbidity. The aim of the study is to determine the most effective thyme plant extract as a natural coagulant to remove water turbidity and compare it with alum as a chemical coagulant.. Materials and Methods: In this study, plant extracts obtained from Thymus vulgaris (Tv), Thymus kotschyanus (Tk), and Thymus eriocalyx (Te) were used as natural coagulants for elimination of water turbidity. Then, the best of plant extract was confirmed by ninhydrin and FTIR analyses and the effect of simultaneous use of plant extract with chemical coagulant of aluminum sulfate (alum) was investigated in the hybrid ratio of 1:1, 2:1, and 1:2. Then, the effect of parameters include of pH, coagulant dose, turbidity removal efficiency, and the most suitable solvent for coagulant extraction were studied. Results: The results of this study showed that among the natural coagulants, Tv had a higher efficiency in elimination of water turbidity, and the highest amounts of turbidity elimination for Tv, alum, and Tv/alum hybrid coagulants was 94, 90, and 96, respectively. According to the results of this study, the most effective solvent for preparing plant extracts was 1M KCl solvent. Conclusion: The natural coagulant removes more turbidity from water than the chemical coagulant, and the simultaneous use of natural and chemical coagulants with a 1:1 ratio was more effective.

The Synergistic Power of Rosehip Seed Powder and Aluminum Chloride in Steel Industry Wastewater Treatment

This study investigates the efficiency of a hybrid coagulation–flocculation process for the treatment of industrial wastewater from the steel industry. The novel method combines a natural coagulant, processed Rosehip Seed Powder (RSP), with a chemical coagulant, aluminum chloride (AlCl3), across varying concentrations and pH levels. The study simulated the pH 8 conditions of iron and steel industrial wastewater and examined the removal of heavy metals, total suspended solids (TSS), chemical oxygen demand (COD), and ammonia–nitrogen (NH3-N). At pH 8, the optimal coagulant dosage was determined to be 0.75:0.75 (g/g) of RSP/AlCl3 powder, resulting in high removal efficiencies across several parameters: 88.29% for COD, 91.85% for color, 99% for TSS, 93.11% for NH3-N, 94.3% for Mn, 98.5% for Fe, 96.7% for Zn, and 99.3% for Ni. The pH optimization demonstrated high removal efficiencies without pH adjudication. The removal of heavy metals at pH 8 demonstrated high efficiencies, with Mn, Fe, Zn, and Al achieving 99.00%, 90.6%, 95.73%, and 92.3%, respectively. These results suggest that no pH adjustment is required when using RSP/AlCl3 for the treatment of iron and steel industry wastewater through the coagulation method.

Porous Iron Electrodes Reduce Energy Consumption During Electrocoagulation of a Virus Surrogate: Insights into Performance Enhancements Using Three-Dimensional Neutron Computed Tomography.

Electrocoagulation has attracted significant attention as an alternative to conventional chemical coagulation because it is capable of removing a wide range of contaminants and has several potential advantages. In contrast to most electrocoagulation research that has been performed with nonporous electrodes, in this study, we demonstrate energy-efficient iron electrocoagulation using porous electrodes. In batch operation, investigation of the external pore structures through optical microscopy suggested that a low porosity electrode with sparse connection between pores may lead to mechanical failure of the pore network during electrolysis, whereas a high porosity electrode is vulnerable to pore clogging. Electrodes with intermediate porosity, instead, only suffered a moderate surface deposition, leading to electrical energy savings of 21% and 36% in terms of electrocoagulant delivery and unit log virus reduction, respectively. Neutron computed tomography revealed the critical role of electrode porosity in utilizing the electrode's internal surface for electrodissolution and effective delivery of electrocoagulant to the bulk. Energy savings of up to 88% in short-term operation were obtained with porous electrodes in a continuous flow-through system. Further investigation on the impact of current density and porosity in long-term operation is desired as well as the capital cost of porous electrodes.

Integrated treatment of black wastewater using sedimentation, constructed wetland, and nanoparticles coagulation

ABSTRACT The aim of the present investigation was to achieve an efficient treatment for black wastewater for non-restricted reuse. The treatment included sedimentation followed by horizontal flow constructed wetland (HF-CW), and finally chemical coagulation using magnetite (Fe3O4) nanoparticles. For the wetland, the average organic loading rate (OLR) was 42.83 biochemical oxygen demand (BOD)/m2day and 71.30 g chemical oxygen demand (COD)/m2 day, while average surface loading rate was 0.185 m3/m2 day. The obtained results revealed that removal percentage of COD, BOD, and total suspended solids (TSS) by sedimentation followed by processing through wetlands was 80.3, 81.6, and 80%, which corresponds to 76, 42.56, and 54 mg/l, respectively. When magnetite nanoparticles were added to the HF-CW effluent at the optimum dose of 25 mg/l in combination with 10 mg/l FeCl3, the overall removal rate increased to reach 95.9, 99.1, 99.17, 92.3, 94.3, 94.3, and 91.3% for turbidity, COD, BOD, TSS, phosphate (PO4), total nitrogen (TN), and sulfide, respectively. The corresponding residual concentrations were 5 NTU, 8, 5, 18 according to table 3, 0.07, 1, and 1.04 mg/l, respectively. According to the national and international regulations, the present final treated effluent can be safely reused as a non-restricted source for agriculture purposes. The overall results revealed that the implemented study is simple, efficient, reliable, and economical, particularly for remote areas, according to the non-restricted reuse requirements.

Experimental investigation and Monte Carlo simulation of landfill leachate treatment using physicochemical method and a non-thermal plasma reactor

ABSTRACT Leachate treatment is one of the challenging subjects in the field of waste management. Leachate as a dumpling sites hazardous byproduct due to the high concentration of chemical oxygen demand (COD) and toxic compounds with dark colour is a potential pollutant of the environment, causing a lot of problems in the absence of treatment and direct discharge to the environment. In this study, the combinatory performance of sequential chemical flocculation and coagulation process and non-thermal plasma (NTP) technology on leachate from the Sarāvān city former controlled landfill, Iran, was investigated. The outcomes of Jar test illustrated that hydrated aluminium sulphate (PAC) was selected the best coagulant compared with hydrated aluminium sulphate (HAS) and ferric chloride (FC) to remove suspended solids and colour. The optimised parameters for 10% PAC pre-treatment were obtained 3 g lime and cationic 0.1 g polyelectrolyte per 1 litre of leachate. After pre-treatment by using jar test, NTP was used to remove turbidity, colour, COD and so forth. The sequential system-based all stages of pretreatment and NTP diminished the turbidity and colour removal to 98.6% and 99.2%, respectively. Furthermore, COD, BOD5, TSS, and TDS were also reduced. As a result, combination of pre-treatment and NTP technology are able to remove the landfill leachate effectively. Monte Carlo calculations exhibited that Al3+ and H2O2 had the most effects to decompose HA (Humic acid) compound in physicochemical pre-treatment and treatment stages.

Microplastic removal using Okra (Abelmoschus esculentus) seed from aqueous solutions

The ubiquitous presence of MPs in water bodies presents an escalating concern, as these minuscule plastic particles could ultimately reach humans via the drinking water supply. This study explores the efficacy and underlying mechanisms of removing PE and PVC MPs using Abelmoschus esculentus seeds (commonly known as okra), a natural and environmentally benign coagulant. Through experiments conducted under varying conditions—such as pH level, coagulant dosage, MP concentration, and EC—using the standard method and a Jar test apparatus, the sedimentation rate was assessed. ZP analysis revealed that charge neutralization and bridging cause pivotal in enhancing the removal efficiency of MPs. FESEM and FTIR analyses corroborated the formation of new bonds during the interaction between the MPs and the okra seed-based coagulant. The findings indicate that the optimal parameters for PVC removal were a coagulant dosage of 70 mg/L, a pH of 10, and an MP concentration of 20 mg/L, achieving a removal efficiency of 80.11%. Conversely, for PE, the maximum removal efficiency of 64.76% was realized at a coagulant dosage of 70 mg/L, a pH of 3, and an MP concentration of 20 mg/L. Abelmoschus esculentus seeds offer a practical and eco-friendly option, potentially substituting chemical coagulants, to efficiently eliminate MPs from aquatic environments.

Evaluation of enhanced chemical coagulation method for a case study on colloidal liquid particle in wastewater treatment: Statistical optimization analysis and implementation of machine learning

Coal mines are one of the largest sources of energy supply and generate significant volumes of wastewater. Chemical coagulation is one of the most effective methods for wastewater treatment. In this research, ferric and aluminum-based coagulants, along with polyacrylamide flocculants with positive, negative, and neutral charges, were utilized in chemical coagulation. After applying the Plackett-Burman screening method, it was found that ferric chloride coagulant, neutral flocculant, and slow mixing duration had the greatest impact. The chemical coagulation process was modeled and optimized by examining these factors using the Box–Behnken statistical design as input parameters and sedimentation velocity as the output. Under optimal conditions, the values for ferric chloride coagulant, neutral flocculant, mixing time in slow mode, and sedimentation velocity were determined to be 106.3 mg/L, 3.98 mg/L, 29.6 min, and 1.10 cm/min, respectively. Under optimal conditions, the removal percentages of pollutants, including TSS, turbidity, TDS, COD, and BOD, were obtained at 100%, 100%, 87%, 93%, and 81%, respectively. The experimental data were fitted using the BBD and ANN methods. Both models demonstrated very high agreement, but the ANN method performed better with an AAD% of 0.66, an MSE of 0.0001, and an R2 value of 0.99. All results were calculated with a confidence level above 98%, indicating that both models had very high reliability in modeling and prediction.

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.

The Efficiency of Chemical and Electrochemical Coagulation Methods for Pretreatment of Wastewater from Underground Coal Gasification

This article compares chemical coagulation with electrocoagulation, two popular methods for the primary treatment of wastewater generated in the process of underground coal gasification (UCG). The primary aim was to determine which method is more effective in the removal of cyanide and sulphide ions, metals and metalloids, as well as organic compounds. In both cases, experiments were conducted in batch 1 dm3 reactors and using iron ions. Four types of coagulants were tested during the chemical coagulation study: FeCl2, FeSO4, Fe2(SO4)3, and FeCl3. In the electrocoagulation experiments, pure iron Armco steel was used to manufacture the sacrificial iron anode. Both processes were tested under a wide range of operating conditions (pH, time, Fe dose) to determine their maximum efficiency for treating UCG wastewater. It was found that, through electrocoagulation, a dose as low as 60 mg Fe/dm3 leads to >60% cyanide reduction and >98% sulphide removal efficiency, while for chemical coagulation, even a dose of 307 mg Fe/dm3 did not achieve more than 24% cyanide ion removal. Moreover, industrial chemical coagulants, especially when used in very high doses, can be a substantial source of cross-contamination with trace elements.

Blended natural and synthetic coagulants for the COD and BOD removal from surface water; optimization by response surface methodology: The case of Gibe river

A novel wastewater treatment method is presented in this study. It combines natural coagulants derived from watermelon seeds with the commonly used synthetic coagulant alum. This research demonstrates a remarkable synergy between these two coagulants in removing nutrients from Gibe River wastewater. Combining natural and chemical coagulants often improves water treatment by enhancing particle destabilization, accelerating floc formation, and broadening the range of removable contaminants, resulting in lower chemical dosage requirements. The optimal mixing ratio, found to be 1 part watermelon seed coagulant to 3 parts alum, leads to improved treatment efficiency. At this ratio, the process achieves impressive removal rates: 98.26 % for total dissolved solids (TDS), 96.10 % for biochemical oxygen demand (BOD), and 95.26 % for chemical oxygen demand (COD). These findings not only validate the use of watermelon seeds as a coagulant but also highlight the combined approach's environmental and economic benefits. This integrated method offers a more sustainable and cost-effective solution for wastewater treatment.

Application of batch electrocoagulation treatment system with aluminium electrodes for simultaneous removal of organic and heavy metal contaminants from Borneo urban rivers

The challenges of sludge management and complex water treatment systems hinder the effectiveness of chemical coagulation in treating heavily contaminated urban river water. Realizing these issues, this study aims to develop a batch electrocoagulation system using aluminum electrodes to generate in-situ aluminum hydroxide coagulants for simultaneous removal of organic contaminants and heavy metals from Borneo urban river water. Subsequent, the treatment system achieves a reduction of 91.67 % of turbidity, 98.29 % of color, 95.16 % of total suspended solids (TSS), 97.78 % of iron, 94.21 % of lead, 21.94 % of pH, and 98.58 % of chemical oxygen demand (COD) with an electric current of 5 A and a residence time of 25 min. Besides, the treated water meets the Malaysia National Water Quality Standards for Class I which making it suitable for domestic consumption. The energy consumption cost for the treatment is only RM 1.48 (USD 0.31) per cubic meter of treated water. Additionally, the analysis of the electrocoagulation flocs reveals the presence of carbon, iron, lead, and various dissolved minerals which indicates effective contaminant removal from urban river. Overall, this study demonstrates the potential of the batch electrocoagulation treatment system as an effective and cost-efficient solution for treating urban river water in Borneo industrial areas.

A literature review of electrocoagulation integrated systems on wastewater treatment

Electrocoagulation (EC), an newly arising electrochemical technology, gained more advances than other electrochemical technologies on wastewater treatment in recent years, including the absence of secondary chemical pollution, simplicity of equipment, and formation of large flocs than traditional chemical coagulation. Combined with existing treatment methods, such as membrane processes, adsorption and activated sludge, EC helps encounter existing issues and enhance the efficiency of current technologies. This paper reviews recent studies on the integration of EC and other technologies to illustrate the performance of the combined systems, especially the role played by EC. Then the advantages and the limitations of the integrated systems are assessed, as well as the challenges and future directions are discussed. Considering the growing global concern over water scarcity and environmental degradation, the application of EC-integrated systems represents a viable and indispensable solution for sustainable water management. This literature review intends to be helpful to researchers, investors, and government officials working and making long-range planning process on wastewater treatments.

Effect of Moringa oleifera Seeds Powder on Metallic Trace Elements Concentrations in a Wastewater Treatment Plant in Senegal.

A wastewater treatment plant (WWTP) prototype coupled with Moringa oleifera seeds (MOSs) was developed to evaluate its effectiveness to reduce metallic trace elements (MTEs) in domestic wastewater. The WWTP is composed of a septic tank (F0) where wastewater is treated by biological processes under anaerobic conditions, followed by a bacterial filter (F1) where wastewater is filtered under aerobic conditions, followed by an infiltration well (F2), which provides additional filtration of wastewater before discharge into the soil. MTEs present in waters can bind with humic substances contained in colloid particles and then be eliminated by coagulation-flocculation with a cationic polyelectrolyte. MOSs contain positively charged cationic polymers that can neutralize the colloids contained in waters, which are negatively charged. Based on this observation, 300 mg·L-1 of MOS was added into F0, 50 mg·L-1 into F1, and 50 mg·L-1 into F2 mg·L-1. MOS activation in samples was performed by stirring rapidly for 1.5 min, followed by 5 min of gentle stirring and 3 h of settling. The data analysis shows that wastewater samples had significant concentrations of MTEs, particularly for Cu, Ni, Sr, and Ti, and sediment samples had high amounts of Cr, Cu, Ni, Sr, Ti, and V. The addition of MOS to F0, F1, and F2 samples resulted in reductions in MTE concentration of up to 36%, 71%, 71%, 29%, 93%, 81%, 13%, 52%, and 67% for Co, Cr, Cu, Ni, Pb, Se, Sr, Ti, and V, respectively. The quantified MTEs (As, Co, Cr, Cu, Ni, Pb, Se and V) in treated samples were reported to be lower than UN-EP standards for a safe reuse for irrigation and MOS proved to be as effective as chemical coagulants such as lime and ferric iron for the removal of MTEs contained in wastewater. These results highlight the potential of MOSs as natural coagulants for reducing MTE content in domestic wastewater. This study could be the first to evaluate the effectiveness of MOS in reducing 10 MTEs, including As, Co, Se, Sr, Ti, and V, which are currently understudied. It could also provide a better understanding of the origin of MTEs found in domestic wastewaters and how an effective treatment process can result in high-quality treated wastewaters that can be reused for irrigation without posing health or environmental risks. However, more research on MOSs is needed to determine the type and composition of the coagulant substance found in the seeds, as well as the many mechanisms involved in the decrease in MTEs by MOSs, which is currently understudied. A better understanding of MOS structure is required to determine the optimum alternative for ensuring the optimal effect of MOS paired with WWTP in removing MTEs from domestic wastewaters.

Fibrin-like calcium release 3D gelatin fiber hemostatic scaffold for interventional surgery

Hemostasis plays a critical role in wound treatment and surgical operations. Blood coagulation can be facilitated by both physical coagulation, involving fibrin and platelets, and chemical coagulation, promoted by calcium ion release. In this study, we fabricated a 3D gelatin fiber and calcium-releasing gelatin sponge (GFGS) to promote the hemostatic process at the wound site. Fibrin-like gelatin fibers electrospun on an ethanol bath were able to form 2–5 µm fibers that maintained a 3D structure and did not dissolve in water. These fibers, which were not densely packed, created a porous space that could entangle with red blood cells, thereby expanding the binding sites. The uncrosslinked gelatin sponge undergoes dissolution upon contact with blood, facilitating blood infiltration and the localized release of calcium ions to enhance the coagulation process. The GFGS demonstrated excellent biocompatibility and hemostatic effects, reducing blood loss by five times compared to regular gauze in a 3 mm diameter wound. By modifying the collector of the electrospinning device and the crosslinking methods, we were able to create a scaffold where gelatin fibers do not adhere to each other and maintain a 3D structure. Additionally, by crosslinking the gelatin to release calcium ions, we were able to enhance the hemostatic effect. This is expected to rapidly prevent and treat wounds occurring after interventional surgeries.

Importance of iron complexation and floc formation towards phosphonate removal with Fe–electrocoagulation

Phosphonates are widely used scale inhibitors, but the residual phosphonates in drainage are challenging to remove because of their chelating capacity and resistance to biodegradation. Here, we reported a highly efficient and robust Fe-electrocoagulation (Fe-EC) system for phosphonate removal. Surprisingly, we found for the first time that phosphonates like NTMP were more efficiently removed under anoxic conditions (80% of total soluble phosphorus (TSP) in 4 min) than oxic conditions (0% of TSP within 6 min) in NaCl solution. A similar phenomenon was observed when other phosphonates, such as EDTMP and DTPMP, were removed, highlighting the importance of iron complexation and floc formation toward phosphonate removal with Fe-EC. We also showed that the removal efficiency of NTMP by electrochemically in-situ formed flocs (97%) was much higher than post-adsorption systems (ex-situ, 40%), revealing that the growth of flocs consumed the active site for NTMP adsorption. Beyond the removal of TSP, 10 % of NTMP-P was also degraded after the electrolysis phase, evidenced by the evolution of phosphate-P. However, this did not happen in anoxic or chemical coagulation processes, which confirms the formation of reactive oxygen species via Fe(II) oxidation in the oxic Fe-EC system. The primary removal mechanism of phosphonates is due to their complexation with iron (hydr)oxide generated in the Fe-EC system by forming a Fe-O-P bond. Encouragingly, the Fe-EC system exhibits comparable or even better performance in treating phosphonate-laden wastewater (i.e., cooling water). Our preliminary cost calculation suggests the proposed system (€ 0.009/m3) has a much lower OPEX under oxic conditions than existing approaches. This study sheds light on the removal mechanism of phosphonate and the treatment of phosphonate-laden wastewater by playing with the iron complexion and flocs formation in classical Fe-EC systems.

Treatment of effluent from a malting processing plant using bio-coagulants

Stringent measures by water authorities worldwide on water clarification has resulted in the use of chemical-based coagulants to be a formidable challenge. This has driven the need to find alternative sustainable coagulants such as plant-based bio coagulants which are readily available, abundant and cost effective in developing countries such as Zimbabwe. In this regard, the effectiveness of treating effluent from a brewery malting processing plant using bio-coagulants (Aloe vera, Cactus opuntia and Okra seeds) was investigated compared to that of a chemical coagulant (Alum). The water pollution parameters that were investigated include turbidity, total dissolved solids, electrical conductivity, temperature and pH. The results showed that Alum was the most effective coagulant as it reduced the turbidity from 734 NTU to 68.3 NTU and Total Dissolved Solids (TDS) from 19,800 ppm to 880 ppm at a dosage of 40 mg/L. Okra seeds had an optimum dosage of 35 mg/L with a turbidity and TDS removal of 88.83% and 95.25% respectively. Aloe Vera had an optimum dosage of 40 mg/L with a turbidity and TDS removal of 74.25% and 95.40% respectively. For Cactus opuntia it was 50 mg/L obtaining turbidity and TDS removal of 74.66% and 95% respectively. The best blend of the bio coagulants had a ratio of (0.17, 0.17, and 0.67) for Aloe vera, Cactus opuntia and Okra seeds respectively. At a dosage of 40 mg/L the turbidity removal was 83.92% and TDS removal was 95.12%. The results indicated that blending the plant-based coagulants had a positive synergistic effect.Graphical

Reduction of organic contaminants from industrial effluent using the advanced oxidation process, chemical coagulation, and green nanotechnology

Municipal wastewater treatment systems use the chemical oxygen demand test (COD) to identify organic contaminants in industrial effluents that impede treatment due to their high concentration. This study reduced the COD levels in tannery wastewater using a multistage treatment process that included Fenton oxidation, chemical coagulation, and nanotechnology based on a synthetic soluble COD standard solution. At an acidic pH of 5, Fenton oxidation reduces the COD concentration by approximately 79%. It achieves this by combining 10 mL/L of H2O2 and 0.1 g/L of FeCl2. Furthermore, the author selected the FeCl3 coagulant for the coagulation process based on the best results of comparisons between different coagulants. At pH 8.5, the coagulation dose of 0.15 g/L achieved the maximum COD removal efficiency of approximately 56.7%. Finally, nano bimetallic Fe/Cu was used to complete the degradation and adsorption of the remaining organic pollutants. The XRD, SEM, and EDX analyses proved the formation of Fe/Cu nanoparticles. A dose of 0.09 g/L Fe/Cu NPs, 30 min of contact time, and a stirring rate of 200 rpm achieve a maximum removal efficiency of about 93% of COD at pH 7.5. The kinetics studies were analyzed using pseudo-first-order P.F.O., pseudo-second-order P.S.O., and intraparticle diffusion models. The P.S.O. showed the best fit among the kinetic models, with an R2 of 0.998. Finally, the authors recommended that technique for highly contaminated industrial effluents treatment for agriculture or industrial purposes.