Chromium removal and water recycling from electroplating wastewater through direct osmosis: Modeling and optimization by response surface methodology

Abstract

Background: Considering the carcinogenic effects of heavy metals, such as chromium, it is essential to remove these elements from water and wastewater. Direct osmosis is a new membrane technology, which can be a proper alternative to conventional chromium removal processes. Methods: The wastewater samples were collected from an electroplating unit, located in Alborz industrial city, Qazvin, Iran. Magnesium chloride was used as the draw solution, and a semipermeable membrane (Aquaporin) was used in this study. The experiments were designed, using response surface methodology (RSM) and central composite design (CCD) with draw solution concentration (0.5- 1.5 M), feed solution concentration (4-12 mg/L), and experiment time (30-90 minutes) as variable factors. The chromium concentration and water flux were also measured, based on atomic absorption spectrophotometry and water flux equation, respectively. Results: Direct osmosis was highly efficient in chromium removal and water recycling. Water flux and chromium removal efficiency were 15.6 LMH and 85.58%, respectively, under optimal conditions (draw solution = 1.27 mol/L, feed solution = 4 mg/L, and experiment time = 90 min). In terms of validity, the results predicted by the quadratic polynomial model were in good agreement with the responses reported in the laboratory. Conclusion: In direct osmosis, the use of magnesium chloride as the draw solution resulted in the acceptable chromium removal from electroplating wastewater. Using this method, chromium concentration in wastewater reduced to a level lower than the discharge standards, established by Iran’s Department of Environment.

The performance of TiO2 /NaY-zeolite nanocomposite in photocatalytic degradation of Microcystin-LR from aqueous solutions: Optimization by response surface methodology (RSM)

“…Response surface methodology (RSM) is a statistical and experimental strategy to get the optimum conditions for a multivariable system and it has been successfully applied to different photocatalytic processes for achieving its optimization using experimental designs. RSM is a suitable strategy which can improve a system and enhance the efficiency of the process without increasing the cost (34,35). So, in this study, in order to determine the optimum conditions for MC-LR removal by the TiO 2 /NaY-zeolite (T/N-Z) nanocomposite under UV light, RSM based on the central composite design (CCD) was used.…”

Assessing biomimetic aquaporin membrane for forward osmosis desalination process: A dataset

“…NaCl rejection property of the Biomimetic-FO membrane was calculated by the following equation.R=Cf−CpCf×100%where C f and C p are the amount of NaCl concentrations for the feed and permeate container [1], [2].…”

Magnetic Hydrogel Composite for Wastewater Treatment

“…The existing technologies for removing pollutants from wastewater are helpful but far from perfect regarding efficiency, their environmental footprint, and economic feasibility. The standard techniques to treat wastewater are adsorption, chemical precipitation, ion exchange, membrane separation, coagulation–flocculation, and electrochemical separation [ 4 , 5 , 6 , 7 , 8 , 9 ]. These techniques have noteworthy shortcomings and constraints, comprising the partial elimination of pollutants, expensive operation and high energy consumption, and production of toxic chemical sludge [ 10 ].…”