Process of eliminating heavy metals from city sewage and sludge

Abstract

The present invention discloses process of eliminating heavy metals from city sewage and sludge. The heavy metal eliminating apparatus consists of simplified sequencing batch bioreactor, concentrating and settling tank and pH regulating tank, and the simplified sequencing batch bioreactor as the main treating apparatus operates in the simplified process comprising feeding sludge, aerobic reaction, aerobic sludge elimination and feeding sludge. The main reactor has exhaust ratio designed in optimal sludge inoculating amount, and the un-exhausted sludge is used for the next batch. The present invention has short treating period, and the treated sludge has the contents of residual Cu, Zn, Cd, Ni and other heavy metal reaching relevant standard.

Description

technical field [0001] The invention relates to a method for removing heavy metals which can solve the problem that the concentration of heavy metals in urban sewage sludge exceeds the standard. Background technique [0002] With the increasing rate of urban sewage treatment in our country year by year, the safe disposal and utilization of the huge output of urban sludge has become the key to restrict the healthy development of urban sewage treatment. As a regular product of urban sewage treatment, urban sludge is rich in plant nutrients such as nitrogen, phosphorus, potassium, and organic matter. After harmless and stabilized treatment, it is a good source of fertilizer and a good soil conditioner. Therefore, the agricultural use of urban sewage sludge has gradually attracted people's attention. However, the influent of most sewage treatment plants in my country is the mixed sewage of industrial wastewater and domestic sewage, and the heavy metal elements in it are concent...

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Problems solved by technology

At present, to solve this problem, the main method is to add passivators and alkaline materials to the sludge to stabilize the heavy metals in it. Since the total amount of heavy metals in the sludge after treatment has not been reduced, the subsequent resource utilization In the process, it is easy to cause a series of negative effects such as the decline of soil quality, crop yield reduction or heavy metal enrichment.

In response to this problem, some experts in my country have proposed to use bioleaching to remove or reduce high-concentration heavy metal elements in sludge. Among them, the two patents of Nanjing Agricultural University on this technology are 02112924.X (Thiobacillus ferrooxidans and its method for removing heavy metals from sludge) and 200410014801.X (method for biological removal of chromium in Thiobacillus thiooxidans and tannery sludge), wherein the former mainly reported the method of removing heavy metals from sludge by using Thiobacillus acidophilus, and the latter The latter mainly invented a treatment process for removing heavy metal chromium in tannery sludge for industrial tannery sludge. However, in this process, there are many treatment structures and a long process flow. Mechanical backflow, not suitable for the removal of heavy metals in municipal sludge

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