Energy Reports (Jul 2023)
Taguchi method in the optimization of municipal wastewater treatment by electrocoagulation integrated with zeolite
Abstract
Electrocoagulation integrated with zeolite in a single step was efficiently applied to the treatment of municipal wastewater with saline water infiltrate. In the first part, the influence of the initial pH values of the solutions and the addition of natural zeolite and NaCl electrolyte on the removal efficiency was investigated. Decreasing of electrical conductivity (17.00–65.79%), turbidity (61.28–97.44%), chemical oxygen demand (77.08–92.71%) and total Kjeldahl nitrogen (33.33–90.48%) was obtained. The initial pH of the wastewater, the addition of zeolite and NaCl electrolyte shows a significant influence on the turbidity reduction, total Kjeldahl nitrogen removal, electrode consumption, and settling properties, while its effects on chemical oxygen demand and electrical conductivity reduction is less pronounced. An increase in solution temperature is higher in an acidic (pH = 4) medium and is related to higher electrode consumption. In the second part, Taguchi’s L9 orthogonal array method was used to optimize municipal wastewater treatment by electrocoagulation and zeolite addition. The effects of initial pH values (pH = 9, pH = 4, and without initial pH adjustment), zeolite addition (natural, synthetic and without), electrolyte addition (NaCl and Na2SO4 and without), and experiment duration time (15, 30 and 45 min) on chemical oxygen demand and turbidity were examined. The results of Taguchi optimization revealed that the most effective factor for the chemical oxygen demand removal is zeolite addition, while the initial pH is for turbidity. Optimal conditions for chemical oxygen demand and turbidity are: the initial pH = 4, without adding electrolyte and an experimental duration of 15 min. However, the addition of zeolite has a dissimilar effect on chemical oxygen demand and turbidity. For chemical oxygen demand, better results are obtained using synthetic zeolite and for turbidity without any type of zeolite.
