Electrocoagulation as an Eco-Friendly River Water Treatment Method

Study of the effect of current intensity on the structural performance of electrogenerated mesoporous aluminum phosphate: application for adsorption

To keep up with the development of contaminants in the water supply, it is required to create new adsorbents or improve current ones. The adsorption capacity of AlPO₄ electrocoagulated with varying current intensities was examined. AlPO₄ was produced by electrolysis in a NaCl solution using aluminum electrodes and a 0.1 M phosphate buffer at varying current intensities. Current efficiency was enhanced. X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy were used to analyze the adsorbents (FTIR). The specific surface area was estimated by the quantity of methylene blue adsorbed by particles in an aqueous solution. Numerous operating factors must be addressed, including pH, starting concentration, adsorbent dose, and contact duration. The electrostatic interaction between positively charged MB molecules and negatively charged adsorbents drives adsorption at alkaline pH. When describing equilibrium adsorption, the Langmuir model is more accurate. Modeling using an adsorption isotherm may further improve the predicted specific surface area. At 0.2 amperes, the observed specific surface area was 2.86 m²/g.

Minimizing the Fluoride Load in Water Using the Electrocoagulation Method: An Experimental Approach

The abundant presence of fluoride (F-) in surface water bodies is an environmental concern because of its effects on human health; medical reports confirmed that fluoride intake above 1.5 mg/L leads to many health complications, including but not limited to weak bones and enamel fluorosis. Thus, the World Health Organisation (WHO) defines 1.20 mg/L as the maximum permissible F- concentration in drinking water. The electrocoagulation method (EC) is globally practised to remove many pollutants from water due to its cost-effectiveness, safety, and ease of use. However, EC has some drawbacks, such as the lack of reactors’ design. In this study, a new EC reactor, which uses four drilled aluminium electrodes and a variant cross-section section container, was designed and used to remove F- from water. The design of the new EC eliminated the need for water mixers. The ability of the new EC unit to remove F- from synthetic water was evaluated at different current densities (CD) (1–3 mA/cm2), electrode distances (ELD) (5–15 mm), pH of the solution (pHoS) (4–10), and initial F- concentrations (IFC) (5–20 mg/L). The outcomes of this study prove that the new reactor could remove as much as 98.3% of 20 mg/l of F- at CD, ELD, pHoS, and IFC of 2 mA/cm2, 5 mm, and 4 and 10 mg/L, respectively.

Adsorption and Its Mechanism of Arsenate in Aqueous Solutions by Red Soil

The removal, and its mechanism, of arsenate from aqueous solutions was investigated using Yunnan red soil. A series of adsorption experiments was designed to disclose the effect of key factors (soil types, soil/solution rates, initial arsenate concentrations, and shaking speeds) on the adsorption capacity of Yunnan red soil for arsenate. The soil/solution ratio was optimized as 0.05 g/100 mL to balance the adsorption capacity and removal efficiency. The optimal shaking speed (225 rpm) not only ensured enough contact frequency between the Yunnan red soil and the arsenate, but also reduced the mass transfer resistance. The results from applying an orthogonal array method showed that the most significant factor affecting arsenate removal efficiency was soil type, followed by the soil/solution ratio, contact time, and shaking speed. The IR spectra of the precipitates further confirmed that the metal arsenide was settled by the Yunnan red soil, indicating that the arsenate ion existed on the red soil surface in the form of protonated bidentate surface complexation of –FeO2As(O)(OH)− and FeO2As(O)2−. These results indicate that Yunnan red soil is promising for the removal of arsenate from aqueous solutions; it may thus be suitable as a new adsorbent for arsenate removal during water treatment.

Effect of pH on Escherichia coli Removal by Electrocoagulation and Elimination Kinetics after Treatment

There are different techniques for removing microorganisms in wastewater, each with its own advantages and disadvantages. Electrocoagulation because of its simplicity has gained great attention and is used for the removal of various ions, organic matters, and microorganisms. In this study, the effectiveness and mechanism of Escherichia coli (E. coli) removal by electrocoagulation process using aluminum and ordinary steel electrodes at different initial-pH and the kinetics of elimination of E. coli in solution after treatment were investigated. Artificial wastewater contaminated by E. coli culture was used in the experiments. The results show that the initial-pH influences significantly the effectiveness of E. coli removal. Under the experimental conditions used, more than 5 log removal of E. coli is obtained, irrespective of the nature of the electrode (ordinary steel or aluminum) and the value of the initial pH. On the one hand, the best rates of elimination are obtained for solutions that are slightly acidic (pH 5.5) and for an alkaline pH (8.5 and 10). On the other hand, the elimination decreases for a neutral solution and for a very acidic solution (pH 2.9) because of the strong resistance developed by E. coli at those pH values. For optimal treatment, the choice of electrode material depends on the initial pH. Furthermore, the study of the kinetics of elimination of E. coli after treatment shows the remanent power of the electrocoagulation process. It allows reducing treatment time and energy consumption, thus reducing the cost of treatment.

Statistical analysis for water quality index for Shatt-Al-Hilla river in Babel city

The work aims to investigate the Water Quality Index (WQI) of the Shatt-al-Hilla River, a branch of the Euphrates river in Babel city, Iraq. Twelve important and influential parameters were taken into account to evaluate the WQI, namely the temperature of water (Temp), total hardness (TH), electrical conductivity (EC), acidity (PH), total dissolved solids (TDS), sulfate (So4−2), calcium (Ca+2), magnesium (Mg+2), sodium (Na+1), biological oxygen demand (BOD), potassium (K) and turbidity. Raw and treated water quality was evaluated using two models, Weighted Calculation and Canadian Cabinet for the Environmental Water Quality Index (CCME WQI). The study area included three water treatment plants, namely New Hilla (NH), Al-Hussein (HE), and Al- Hashimyah (HA), which discharge their treated water into the Shatt-al-Hilla river. Raw and treated water samples were collected and tested regularly for nine months, from October 2020 to June 2021. The results showed all chemical and physical parameters (for both raw and treated water) met the Iraqi standards except Ca+2, turbidity and EC for raw water and temperature for treated water.

The multiplex PCR assay detection of Staphylococcus sciuri antibiotic resistance, mecA gene, and the inhibitory effect of root exudate of Nigella sativa (black seeds) treated with magnetized water

121 bacterial samples isolated from wounds from both sexes and all age groups were collected from Salahadin General Hospital, Salahadin provenance, Iraq. Only 8 Staphylococcus sciuri (S. sciuri) isolates were identified. The bacterial isolation showed the highest sensitivity to Amoxicillin/Clavulanic acid, Cefotaxime, Methicillin, Streptomycin, and Vancomycin and resistance to all other antibiotics. The root exudates of black seeds were used for 10 and 20 days for both treatments with and without magnetized water, and the exudates were superior when using magnetized water for 20 days. Antibiotic resistance and the mecA gene were investigated, and a multiplex PCR assay was used to detect the mecA gene in S. sciuri. Optimized conditions were used to amplify mecA fragments that encode methicillin resistance.

Electrochemical process for simultaneous removal of chemical and biological contaminants from drinking water

Simultaneous management of chemical and biological contaminants in drinking water has been presented through modification in conventional electrocoagulation (EC) process. Traditional EC process using iron and aluminum electrodes removed metals but did not affect microbiological contaminants to a greater extent. Iron anode composition was amended by addition of zinc for desired antimicrobial output. To evaluate the efficiency of this system, samples were spiked with multiple element standard and microbial cultures to human unsafe contamination level. Modified EC process removed both types of contaminants making water safe for human consumption within the prescribed regulatory guidelines set by WHO/NSDWQ within 4 min. This setup removed chemical contaminants up to 100% including nitrates, fluoride, arsenic, beryllium, chromium, copper, mercury, vanadium, zinc, nickel, phosphorus, and lead. A substantial removal in cadmium (89.8%), cobalt (75.7%), and selenium (46.7%) was computed. The treatment could not prove good results for removal of boron, barium, lithium, and strontium from the spiked sample. The compositional analysis of flocs screened after spiked sample treatment confirmed the physical adsorption of metals at floc surface. Treatment technique comprehensively proved equally efficient for disinfection of most common microbiological contaminations including E. Coli, fecal coliforms, total coliforms, total plate count, Staphylococcus auseous, and Pseudomonas aeruginosa within 5 min. In EC process 220V voltage was applied through rectifier at electrodes having 15.6 cm² surface area and 15 mm apart in 1-L water sample batches, where current varied from 0.8 to 1.6 ampere. The outcomes of the current experiment are of novel significance regarding simultaneous removal of metals and microbiological contaminants from drinking water which is not reported in previous treatment studies.

The Tolerance of Anoxic-Oxic (A/O) Process for the Changing of Refractory Organics in Electroplating Wastewater: Performance, Optimization and Microbial Characteristics

In order to investigate the tolerance of an anoxic-oxic (A/O) process for the changing of refractory organics in electroplating wastewater, optimize the technological parameters, and reveal the microbial characteristics, a pilot-scale A/O process was carried out and the microbial community composition was analyzed by high-throughput sequencing. The results indicated that a better tolerance was achieved for sodium dodecyl benzene sulfonate, and the removal efficiencies of organic matter, ammonia nitrogen (NH4+-N), and total nitrogen (TN) were 82.87%, 66.47%, and 53.28% with the optimum hydraulic retention time (HRT), internal circulation and dissolved oxygen (DO) was 12 h, 200% and 2–3 mg/L, respectively. Additionally, high-throughput sequencing results demonstrated that Proteobacteria and Bacteroidetes were the dominant bacteria phylum, and the diversity of the microbial community in the stable-state period was richer than that in the start-up period.

Electrocoagulation as a Promising Defluoridation Technology from Water: A Review of State of the Art of Removal Mechanisms and Performance Trends

Fluoride ions present in drinking water are beneficial to human health when at proper concentration levels (0.5–1.5 mg L−1), but an excess intake of fluoride (>1.5 mg L−1) may pose several health problems. In this context, reducing high fluoride concentrations in water is a major worldwide challenge. The World Health Organization has recommended setting a permissible limit of 1.5 mg L−1. The application of electrocoagulation (EC) processes has received widespread and increasing attention as a promising treatment technology and a competitive treatment for fluoride control. EC technology has been favourably applied due to its economic effectiveness, environmental versatility, amenability of automation, and low sludge production. This review provides more detailed information on fluoride removal from water by the EC process, including operating parameters, removal mechanisms, energy consumption, and operating costs. Additionally, it also focuses attention on future trends related to improve defluoridation efficiency.

The Removal of Residual Concentration of Hazardous Metals in Wastewater from a Neutralization Station Using Biosorbent-A Case Study Company Gutra, Czech Republic

This article deals with the possibility of using a biosorbent in the form of a mixture of cones from coniferous trees to remove the residual concentration of hazardous metals contained in hazardous waste, which is disposed of in a neutralization station. The efficiency of the tested biosorbent in removing Ni, Zn, Cu, and Fe was monitored here. Laboratory research was carried out before the actual testing of the biosorbent directly in the operation of the neutralization station. With regard to the planned use of the biosorbent in the operational test, the laboratory experiments were performed in a batch mode and for the most problematic metals (Ni and Zn). The laboratory tests with real wastewater have shown that the biosorbent can be used to remove hazardous metals. Under the given conditions, 96% of Ni and 19% of Zn were removed after 20 min when using NaOH activated biosorbent with the concentration of 0.1 mol L⁻¹. The inactivated biosorbent removed 93% of Ni and 31% of Zn. The tested biosorbent was also successful during the operational tests. The inactivated biosorbent was applied due to the financial costs. It was used for the pre-treatment of hazardous waste in a preparation tank, where a significant reduction in the concentration of hazardous metals occurred, but the values of Ni, Cu, and Zn still failed to meet the emission limits. After 72 h, we measured 10 mg L⁻¹ from the original 4,056 mg L⁻¹ of Ni, 1 mg L⁻¹ from the original 2,252 mg L⁻¹ of Cu, 1 mg L⁻¹ from the original 4,020 mg L^–1 of Zn, and 7 mg L⁻¹ from the original 1,853 mg L⁻¹ of Fe. However, even after neutralization, the treated water did not meet the emission limits for discharging into the sewer system. The biosorbent was, therefore, used in the filtration unit as well, which was placed in front of the Parshall flume. After passing through the filtration unit, the concentrations of all the monitored parameters were reduced to a minimum, and the values met the prescribed emission limits. The biosorbent was further used to thicken the residual sludge in the waste pre-treatment tank, which contributed to a significant reduction in the overall cost of disposing of residual hazardous waste. This waste was converted from liquid to solid-state.

A novel technique of COD removal from electroplating wastewater by Fenton-alternating current electrocoagulation

The present study employs a novel technique combining Fenton reaction with sinusoidal alternating current electrocoagulation (FSACEC), which is used to remove chemical oxygen demand (COD) in the simulated electroplating wastewater with the advantages of low energy consumption and small sludge. Fe²⁺, produced from the dissolution of Fe anodes in the FSACEC process, reacts with H₂O₂ to generate more ·OH and forms the iron hydroxide precipitates. The higher efficiency of COD removal is achieved through both effects of the oxidation reaction and the physical adsorption. The scanning electron microscopy (SEM) analysis shows that the particle size of FSACEC products is between 30 and 40 nm, which is less than the Fenton-direct current electrocoagulation products. The effect of the current concentration (I_V), initial pH (pH₀), and the addition of hydrogen peroxide (30% H₂O₂) was discussed on the optimal process parameters. In pH₀ 2.0 wastewater, applying current concentration of 1 A dm^-3, the addition 20 cm³ dm^-3 30% H₂O₂, the removal efficiency of COD reached 94.21% and the residual COD in wastewater was only 60 mg dm^-3 after 90 min of operation. In order to investigate the maximum removal efficiency in a certain period of operation, the larger current concentration is applied to remove COD. The FSACEC process exhibits the higher removal COD efficiency and wider operation range of pH₀ than the single Fenton technique. The FSACEC process is in accordance with the kinetic law of the pseudo-second-order kinetic adsorption model.