易欣怡,韦朝海,吴超飞,吴海珍.O/H/O生物工艺中焦化废水含氮化合物的识别与转化[J].环境科学学报,2014,34(9):2190-2198
O/H/O生物工艺中焦化废水含氮化合物的识别与转化
- Identification and transformation of nitrogen compounds in coking wastewater during O/H/O biological treatment process
- 基金项目：国家自然科学基金（No. 21037001，51278199，21377040）
- 易欣怡
- 1. 华南理工大学环境与能源学院, 广州 510006
- 韦朝海
- 1. 华南理工大学环境与能源学院, 广州 510006;2. 工业聚集区污染控制与生态修复教育部重点实验室, 广州 510006
- 吴超飞
- 1. 华南理工大学环境与能源学院, 广州 510006;2. 工业聚集区污染控制与生态修复教育部重点实验室, 广州 510006
- 吴海珍
- 3. 华南理工大学生物科学与工程学院, 广州 510006
- 摘要：富氮缺磷是焦化废水的特征之一，而含氮化合物存在多种组分与形态，其在废水处理过程中的利用与顺序会影响工艺条件与达标可行性，因此，通过识别含氮化合物的种类并了解其转化可以获得优化的运行工况.为考察含氮化合物的去除过程，在与实际生产330×104 t·a-1焦炭工艺相配套的焦化废水处理工程O/H/O生物工艺中，检测了原水与生物出水中含氮化合物的种类与形态，以及各单元工艺中无机氮及部分有机氮化合物的浓度，分析特征化合物的转化.研究发现，焦化废水原水中含有的无机氮化合物主要为NH4+-N（33.6%）、氰化物（7.5%）、硫氰化物（40.4%），NO2--N及NO3--N的含量约为1%，折算总氮浓度约为240 mg·L-1，占82.5%左右；有机氮当中，可检测到胺类14种，有机腈类22种，含氮杂环化合物76种，以总氮形式表达其浓度低于50 mg·L-1，约占17.5%.处理过程中，O1反应器能够把氰化物、硫氰化物氧化为氨氮，有机氮发生形态改变；H反应器中，环状含氮化合物通过水解作用实现分子开环转变为氨氮，回流液中的硝态氮实现反硝化转变为氮气；O2反应器能够将低价状态的含氮化合物转变为硝态氮；生物出水中，硝态氮占总氮的70%以上；含氮化合物的转化受反应器的性质与运行条件控制，表现出复杂性.研究指出，焦化废水总氮的控制需要依据含氮化合物种类与形态判断、工艺组合及条件优化综合考虑.
- Abstract：Coking wastewater is a typical industrial wastewater containing substantial amounts of nitrogen but limited amounts of phosphorus. There are multiple inorganic and organic nitrogen compounds in the coking wastewater; the transformation and removal of them in an order of preference is an important factor affecting the technologies selected for the wastewater treatment plant (WWTP). Therefore, identifying the nitrogen compounds in the raw wastewater and understanding how they can be transformed are of crucial importance to optimize operational parameters for the WWTP. This study aims to (ⅰ) detect different forms of nitrogen compounds in the raw wastewater and the effluent from the biological treatment, (ⅱ) determine the concentrations of inorganic nitrogen compounds and some of organic nitrogen compounds available in different units, and (ⅲ) investigate the transformation and removal of some specific nitrogen compounds. Samples were taken from a practical coking WWTP that treats wastewater delivered from a 330×104 t·a-1 coking-producing factory and adopts an O1 (aerobic)/H (hydrolytic)/O2 (aerobic) biological process as the core technology. Results showed that inorganic nitrogen compounds in the coking wastewater were primarily composed of ammonia (33.6%), cyanide (7.5%), and thiocyanate (40.4%) with a total nitrogen concentration about 240 mg·L-1. Organic nitrogen compounds in the coking wastewater consisting of 14 kinds of amines, 22 kinds of organic nitriles and 76 kinds of nitrogen-containing heterocyclic compounds were detected, with a total nitrogen concentration about 50 mg·L-1. After the first aerobic biological treatment, cyanide and thiocyanate were oxidized to ammonia, and the forms of some organic nitrogen compounds were also changed. After the hydrolytic process, nitrogen-containing heterocyclic compounds were transformed to ammonia and nitrate from the cycled O2 effluent was eventually reduced to nitrogen. After the second aerobic biological treatment, ammonia was oxidized to nitrate. It was found that nitrate accounted for more than 70% of total nitrogen in the biological effluent. The experiment results indicated that the transformation of nitrogen compounds in the coking wastewater was complicated, depending on the properties of reactors and their operational conditions. Our findings suggest that the control of total nitrogen in the coking WWTP should take into consideration the identify of nitrogen compounds, the combination of different treatment processes, and the optimization of operational conditions.
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