Optimal conditions of paint wastewater coagulation with gastropod shell conchiolin using response surface design and artificial neural network-genetic algorithm

Abstract

The potential of gastropod shell conchiolin (GSC) (a waste product of the deprotenization stage of chitosan production) as one of the alternatives to chemical coagulants has been explored for treatment of paint industrial wastewater (PW). The accuracy of response surface design (RSD) and the precision of artificial intelligence in predicting and optimizing the process conditions were harnessed in raising experimental design matrix and response optimization, respectively for the bench scale jar test coagulation experiment. PW was characterized using American Public Health Association standard methods. Extraction of conchiolin was done via alkaline extraction method. PW contains 2098 mg/l total suspended solid above discharge limit (1905 mg/l). Fourier transform infrared (FTIR) spectrum of GSC revealed a broad N–H wagging band at 750–650 cm−1 indicating the presence of secondary amine linked to the presence of protein. Turbidity removal from PW via one factor at a time was found to be a function of pH, GSC dosage, temperature and time. Artificial neural network response prediction shows 92% correlation with the RSD experimental result. The optimal conditions obtained via genetic algorithm for the response optimization at the best pH of 4 indicate optimal turbidity removal of 98% at GSC dosage, time and temperature of 4 g, 20 min and 45 °C, respectively.