Dynamic Test Of Removal Heavy Metal From Sludge By Bioleaching Process

With the popularity of sewage treatment plants, the sludge problem is more and more serious. Based on The cost of treatment and the principle of waste recycling, agricultural use is considered the most promising methods of sludge treatment, but heavy metal in sludge is always a limiting factor. In many heavy metal removal ways, bioleaching method, because of its low consumption, low operation cost, and high heavy metal removal rate, attracts people's attention.This paper firstly introduces the concept, characteristic, treatment methods of sewage sludge, and its land-use prospects and constraints, describing the sources, pollution and removal methods of heavy metals, and then reviews the concept, mechanism, factors, reactor types, origin, development and the prospects of bioleaching method. The main research contents are as follows.(1) Measure the concentrated sludge collected from the sewage treatment plants located in north and mid Taiyuan. The result shows that the contents of Zn and Ni is more than China's acidic soil standard about the use of sludge, the contents of Cd is almost close to the Standard, and the amount of nutrients in sewage sludge are higher than that in the Wet compost. Therefore, the sewage sludge has high land-use value, but the contents of Zn, Ni, Cd must be effectively reduced to reach the standard of agricultural sludge.(2) Research the operation parameters of dynamic bioleaching test. First, the experiment group designed a bioleaching system. As the core component of the system,reactor is made of glass and its external shape is cylindrical. At present, most operation parameters of dynamic bioleaching test reference to the static experimental value. The experiment,creatively research the operation parameters of dynamic bioleaching test. The result shows that optimum Sulfur addition is 4g/L, optimum inoculation concentration is 3%, optimum temperature is 28℃, optimal stirring speed is 150r/min, and the best way for mixing stirring is 20 min interval 40 min.(3) Study the change of sludge quality during the dynamic bioleaching process. The result shows that during the bioleaching pH value is substantially reduced, sedimentation and dewatering properties is improved, heavy metals are effectively removed, and nutrients are lost. In addition, the result also shows that the sewage sludge is still rich in nutrients, and also able to basically meet the land-use requirement after the bioleaching.The research of dynamic bioleaching test is designed to provide a theoretical basis for the promotion of bioleaching technology.