科研之友
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摘要
Tannery wastewater usually contains a high content of ammonia nitrogen (NH3-N), which increases the difficulty of wastewater treatment. The objective of this work is to investigate the distribution of NH3-N in wastewaters from beamhouse processes and analyze the origin of NH3-N in each operation, so that the strategies that can reduce NH3-N at the origin could be suggested. Not surprisingly, the results demonstrate that NH3-N mainly concentrates in deliming and bating wastewaters due to the addition of ammonium salts in these two operations. This problem can be solved by using non-ammonia deliming and bating agents. A small quantity of NH3-N arises from washing and soaking processes because of decomposition of proteins by microorganisms. But the NH3-N in washing and soaking wastewaters may considerably increase when skins are badly preserved or the microorganisms in soaking float are not properly inhibited. Therefore, the effective antibacterial measures are important to diminish the production of NH3-N in beam house processes. As for unhairing/liming process, NH3-N in wastewater is mainly originated from hydrolysis of proteins, such as keratin and collagen, by strong alkali. Hair-saving unhairing and pelt swelling under milder conditions favor the decrease of NH3-N discharge. In fact, the amount of organic nitrogen released from washing, soaking and liming processes is much more than NH3-N. The experimental results indicate that the organic nitrogen mainly results from non-collagen proteins and their hydrolysates. This means the discharge of organic nitrogen is difficult to be avoided, and it may constitute a threat to end-of-pipe treatment of NH3-N.
- 出版日期2012-2
- 单位四川大学
