Anti-bacterial performance, disinfection by-products control and optimization strategy in distributed potable water supply using electrolysis

Abstract

Distributed potable water supply can satisfy the pursue for high quality drinking water, but has a risk of microbial pollution induced by water stagnation. Electrolysis shows a good foreground to deal with the problem. In this paper, the anti-bacterial performance and disinfection by-products potential were studied and compared in different stagnated water samples with methods of electrolysis and chlorination. The research had several findings. First, electrolysis should run at least 30 min to decrease hetertrophic plate counts below the hygiene standard (<500 cfu/mL), which was similar to chlorination and was better than hydraulic cleaning. A viable but nonculturable calculation model was proposed to evaluate the viability of bacteria after electrolysis and chlorination. Electrolysis showed better performance than chlorination in decreasing the proportion of viable but nonculturable bacteria and opportunistic pathogens. Second, electrolysis contributed to disinfection by-products control. Differential spectra were used to evaluate disinfection by-products potential, and the values of DlnA350 and DA272 were lower in electrolyzed water than those in chlorinated water. Third, standard queueing theory and multi-objective programming were used to optimize electrolysis. Decreasing the waiting time of disinfection and the total running time were main targets of optimization. Circulation flow electrolysis and pulse chlorination can keep outlets from distributed purifiers biosafe in full time, and reduce the waiting time for consumers to collect biosafe water. The ideal running and pausing time were 0.5 h and 2 h, to decrease the mathematical expectation of waiting time to none.