Sludge digestion enhancement and nutrient removal from anaerobic supernatant by Mg(OH)(2) application

Anaerobic sludge digestion is a widely adopted process for sludge stabiliza tion. Phosphate removal from anaerobic supernatant is necessary to limit th e phosphate returned to the head of the treatment plant, thereby improving the overall treatment efficiency. In this study, magnesium hydroxide (Mg(OH )(2)) was used to improve the sludge digestion efficiency and to remove pho sphorus from anaerobic supernatant. The anaerobic sludge digestion experime nt was conducted at a pilot scale, and the results showed that applying Mg( OH)(2) to anaerobic sludge digester resulted in a larger reduction in SS an d COD, a higher biogas production rate, a lower level of phosphate and ammo nia nitrogen concentrations in the sludge supernatant and an improved sludg e dewaterability. Research results at both lab scale and pilot scale on pho sphorus removal from anaerobic supernatant using Mg(OH)(2) showed that a hi gh removal of phosphorus can be achieved through the addition of Mg(OH)(2). The required reaction time depends on the initial phosphorus concentration and the Mg(OH)(2) dosage.