On-line control of magnesium hydroxide dosing for sulfide mitigation in sewers

Magnesium hydroxide (Mg(OH)2) is commonly dosed in sewer systems to control corrosion and odour problems by preventing sulfide transfer from the liquid to the gas phase. Current dosing practices do not take the dynamics of sewage flow and sulfide production into consideration. This paper presents the development of an on-line control methodology for the optimised dosing of Mg(OH)2, based on pH measurement and the wastewater buffer capacity. Sewage acidification due to fermentative processes is also taken into consideration. Simulation results showed an improved pH control with reduced chemical consumption.