Optimizing functions of coagulants in treatment of wastewater from metalworking fluids: Prediction by RSM method

Abstract

Background: Coagulation is a treatment procedure for metalworking fluids (MWFs). This study aimed to optimize coagulation using four coagulants and compare the results. Methods: In this research, the outputs of a coagulation procedure in chemical oxygen demand (COD) removal, turbidity, and the release of oil were investigated using four coagulants, ferric chloride (FeCl 3 ), ferric sulfate (Fe 2 (SO 4 ) 3 , calcium chloride (CaCl 2 ), and aluminum sulfate (Al 2 (SO4) 3 . To optimize the process, a central composite design (CCD) and response surface methodology (RSM) were used. Results: Under optimal conditions for using calcium chloride (coagulant concentration 4.2 g/L and pH 3.71), COD and turbidity removals and oil released were respectively 93%, 96.9%, and 31.8 mL. COD and turbidity removals and oil released using aluminum sulfate as a coagulant under optimal conditions (5.36 g/L, pH 4.64) were 75.7%, 89.9%, and 28.9 mL, respectively. With respect to ferric sulfate under optimal conditions (6.25 g/L, pH 3.4), COD and turbidity removals were 60% and 84.1%, respectively and oil released was 16.1 ml. COD and turbidity removals and the greatest amount of oil released by ferric chloride under optimal conditions (3.16 g/L, pH 3.5) were 54.4%, 84.7%, and 15.9 ml, respectively.

Evaluation of the efficiency of electrocoagulation process in removing cyanide, nitrate, turbidity, and chemical oxygen demand from landfill leachate

“…Huang believed nitrate reduction at acidic pH is possible in two ways: 1) H + ions participate directly in the nitrate reduction reaction as nitrate complex compounds. 2) H + ions affect nitrate uptake at the reactive site (26,27). Lee et al investigated the removal of ammonia nitrogen and COD from landfill leachate by electrocoagulation.…”

Optimization of saline wastewater treatment using electrochemical oxidation process: Prediction by RSM method

“…Several types of industrial wastewaters including pharmaceuticals, tannery and leather, textile, meat processing, fish, and marine products contain high concentrations of salts [6,7]. Salt can also be found at high concentrations in the leachate of urban landfill sites, contaminated groundwater, and the wastewaters resulting from mining operations and recycling units of gas and oil industries [[8], [9], [10]]. Fish processing industries need large amounts of sodium chloride for fish preservation.…”

Treatment of mine wastewater using a coal fly ash-based coagulant: Coagulation adsorption isotherm study

“…Reducing the investment cost of producing aluminium and iron coagulants from industrial-grade ores is difficult due to their limited prices (Hu et al 2017). However, other elements such as silicon, calcium and magnesium ions have been reported as potential coagulants for wastewater treatment (Jamali and Moradnia 2018;Verma et al 2012;Zhang et al 2012). A composite coagulant (e.g., a coagulant based on aluminium, iron, silicon, calcium and magnesium components) is ideal as it is effective due to its multivalence, which strongly attracts colloids and guarantees a high degree of removal (Apua 2020).…”