| In order to develop the recycling economy,a manganese industry company in NingXia province plans to reuse the manganese slag and desulfurized gypsum as raw materials to build an acid production project with an annual output of 2×400,000 tons of gypsum.This project is expected to consume a large amount of desalinated water to supplement the circulating water and production water,and at the same time,domestic sewage,concentrated drainage of circulating water,sewage acid and acid-containing wastewater will be produced.A sewage treatment station which is a key part of this gypsum acid production project is planed to build to resolve the recycling water problem with no external waste water drainage.According to the characteristics of the sewage,wastewater and water production,in this thesis the process of wastewater treatment and comprehensive utilization was studied,and the process route was drawn up.Domestic sewage is treated by “hydrolysis + contact oxidation + MBR” process,and treated water was added into the fresh water system at last.The fresh water adopts the process of “clarification + ultrafiltration + reverse osmosis” process to prepare for the desalinated water,which is used to supplement the circulating water.Sewage acid and acidic wastewater were mixed and pretreated with “lime-iron salt” method and sulfide method.After the recycled process,the sewage is collected and disposed into the other two streams of wastewater,then the combined processes of “softening + high efficiency reverse osmosis +DTRO + evaporation” are adopted to realize the recovery and utilization of wastewater.The process proposed in the thesis conform to the national guidelines for energy conservation and recycling economy,it could save 860,000 tons of water resources annually in the first implementation year. |
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