Abstract:

Optimizing the design parameters of biological denitrification process according to the water quality has a great significance in improving denitrification treatment effect and reducing operation cost. The concentration of nitrate is much larger than ammonia nitrogen in high nitrogen-containing wastewater generated by some specific industries. For this case， UASB reactor can be selected as the main denitrification tank for the formation of anoxic conditions， while considering biochemical denitrification process. The design parameters of UASB denitrification tank can be set as follows： 1.875 ≤ carbon to nitrogen ratio ≤ 3.75 （sodium acetate as carbon source）， TN volume load between 1-2.5 kg/（m³·d^-1）， inner-circulating reflux ratio is 50%-100%， reflux point is between the suspension zone and the three-phase separator， inside up flow velocity is 1-3 m/h， and aspect ratio is 1-5. In the example， when the treatment volume was 250 m³/h， the influent nitrate was 350 mg/L， and the effluent nitrate was 55 mg/L， the total equipment investment of the project was about 60 000 RMB/t （including all subsidiary process sections）， and the operation cost was 10.17 RMB/t. Applying this process to treat wastewater with high nitrogen content， it saves more land than the AO process under the same water quality conditions， thus saving the civil construction investment. The estimation of sludge yield coefficient and surplus sludge amount， as well as whether the mixture reflux ratio can follow the formula of AO method， etc. still need further study.

Key words: denitrification, UASB, nitrate, calculations for process

摘要：

根据水质对生物脱氮工艺的设计参数进行优化，对于提高脱氮处理效果及降低运行成本具有重要意义。某些特定行业产生的高含氮废水中，硝态氮的浓度远大于氨氮，对于这种情况，在考虑生化脱氮工艺时，可以选用UASB反应器作为形成缺氧条件的主反硝化罐。UASB反硝化罐的设计参数选取可参考：1.875≤碳氮比≤3.75（乙酸钠为碳源），TN容积负荷取1~2.5 kg/（m³·d），自循环回流比为50%~100%，回流点在三相分离器以下悬浮区以上，反应罐内上升流速为1~3 m/h，高径比1~5。实例中，处理水量为250 m³/h，进水硝态氮为350 mg/L，出水硝态氮为55 mg/L时，项目总设备投资在6万元/t左右（含全部附属工艺段），运行费用为10.17元/t。采用该工艺处理高含氮废水时，相比同等水质条件下的AO工艺更节省用地，从而可节省土建投资。选用该工艺时，污泥产率系数和剩余污泥量的估算，以及混合液回流比的选择是否可沿用AO法的公式等，仍需进一步研究。

关键词: 脱氮, UASB, 硝态氮, 工艺计算

CLC Number: 

• X703