Anaerobic Microbial Treatment Of Acidic Iron-containing Sulfate Wastewater With Soybeans As Carbon Resource

Anaerobic microbial treatment of acidic iron-containing sulfate is a new technology. The technology makes fully use of the metabolism of sulfate reducing bacteria, which has a lot of advantages, such as simple process unit, low running rate, wide range of applications, treating wastewater with organic waste, conveying no secondary pollution, and so on. So it received extensive attention by environmentalists. The life activities of sulfate reducing bacteria need carbon resource for energy. The carbon resource which can be used for sulfate-reducing bacteria has more than 100 Species. Not only does it provide energy and electron donor for the sulfate-reducing bacteria, but also removal sulfate in a wide range of acidity inexpensively. What's more this kind of carbon resource has not been reported.This thesis proposes that using natural organic Soybeans as carbon resource for sulfate-reducing bacteria. Soybeans are rich in protein, fat, carbohydrates and calcium, phosphorus, iron and other mineral elements. Protein is the main material composition of microbes, fat and carbohydrate can provide energy for microbial and mineral elements can maintain a normal life for microbial activities, amino acid-the decomposition product of protein can neutralize the acidity of waste water, reducing its pH.We compare fermented soybeans with glucose, using them as carbon resource. First, we use fermented soybeans as carbon resource, in the condition of the surrounding minimum acidity-1.5, the removal rate of sulfate is 73.85%; using glucose as carbon resource, in the condition of the surrounding minimum acidity-2.8, and the removal rate is only 57.5%. Then, we use fermented soybeans as carbon resource, in the condition of the surrounding minimum acidity-3.0, the highest removing rate of sulfate is 96.3%; using glucose as carbon resource, in the condition of the surrounding minimum acidity-7.0, and the highest removal rate of sulfate is 95%. We can find that, when treating fermented soybeans as carbon resource, the best removal rate of sulfate and the best removal rate of COD are lower than that of glucose. Therefore, using fermented soybeans as carbon resource can adapt to lower pH wastewater.We did dynamic process test with AMMBR. Taking minimum pH of wastewater, COD/SO42-, hydraulic retention time, maximum sulfate density into consideration, finally, we confirmed the optimal process parameter was that the Minimum pH of wastewater was 2.0, COD/SO42- was 3.0, hydraulic retention time was 28h.We studied the ferric iron sulfate wastewater and the ferrous iron sulfate wastewater. When the Fe2+ density lower than 300mg/L, the removal rate of Fe2+ is above 82%, SO42- removal rate is above 81%; then we change the condition, when the Fe3+ density below 400mg/L, Fe3+ removal rate is above 80.5%, and SO42- removal rate is above 82%. It is higher than the removal rate of the anaerobic microbe wastewater dealing method, which is adopted by domestic and abroad companies, whose rate is about 82% with Fe3+ density below 100mg/L.In conclusion, we can infer that using soybeans as sulfate-reducing bacteria's carbon resource will be a successful solution for dealing with the economical aspect of carbon resource and low acidity sulfate wastewater problems. Soybeans are cheap, available to gain easily, and also effective. I'm sure that the carbon resource will be widely applied in the wastewater dealing industry industrialization.