Bioleaching of Heavy Metals from Pig Manure with Different Initial pH

Influence of different initial pH value on removal effect of heavy metals from pig manure by bioleaching technique was studied. Results showed that scope of initial pH value favorable for bioleaching of pig manure is wider. Even under weak alkaline condition with initial pH of 8, pH value of pig manure liquid can also decrease rapidly with bioleaching time, which decreases to 1.37 in the first 12d of bioleaching, with bioleaching rate of Cu, Zn and Cd up to 90.76%, 97.97% and 80.45% respectively. Initial pH value has a certain influence to bioleaching speed, decreasing initial pH value can shorten the bioleaching process. According to the reduction of influence extent of initial pH to bioleaching process, the order of heavy metals is ranked as Cu, Zn and Cd. Pig manure liquid with initial pH of 5 can finish bioleaching process in 9d, with bioleaching rate of Cu, Zn and Cd up to 93.83%, 99.24% and 70.98% respectively.