Chlorine and Acid Conditioning of Sludge

Laboratory studies were conducted to evaluate the relative effectiveness of chlorination and acidity in the conditioning of selected primary, anearobically digested, and aerobically digested sludges. Principal parameters of interest were filterability of sludge after conditioning as determined by specific resistance, release of organic material to the filtrate during conditioning as indicated by chemical oxygen demand, and release of typical metals, including zinc, copper, and chromium, during conditioning. The results indicated that many of the beneficial effects of the chlorine oxidation process are the result of acid treatment alone and are not dependent on the addition of large dosages of chlorine. The work also showed that application of chlorine may increase possibly deleterious effects in the conditioning process.