厌氧—好氧组合工艺处理DHA废水的试验研究

发布时间：2018-08-05 20:13

【摘要】：DHA是一种对人体心血管系统、神经系统及抗炎免疫系统非常有益的不饱和脂肪酸,也是人类健康不可或缺的营养要素。江苏某生物科技有限公司采用发酵工艺生产DHA系列产品,生产过程中产生一定量高浓度难降解有机废水,废水中COD浓度为53000~54000mg/L,BOD5/COD为0.09~0.1,可生化性能极差,为此试验采用“铁炭微电解—UASB—MBR”组合工艺,考察各系统及组合工艺对COD浓度的去除变化,获取DHA废水处理的最佳运行参数。试验采用铁炭微电解法对DHA废水进行预处理。由正交试验可得,影响铁炭微电解反应COD去除效率的因素为铁炭比pH值反应时间搅拌强度。根据单因素优化试验可得,反应最佳运行条件为:pH为3,反应时间为4h,铁炭比为3:1,搅拌强度为300r/min。在最佳运行条件下,铁炭微电解对DHA废水的COD去除率为45%左右,BOD5/COD值由0.1提升至0.31,很大程度提高了DHA废水的生化性,为后续的生化处理创造了良好条件。试验采用UASB反应器对DHA废水进行厌氧处理。经过67天的调试运行,反应器容积负荷达到8kgCOD/(m3·d),并可保持稳定运行,出水COD浓度为1500mg/L左右,COD去除率为81%左右。试验研究了不同容积负荷对COD去除效率的影响。研究发现,当容积负荷大于8kgCOD/(m3·d),COD去除率明显下降,出水水质极不稳定。此外,考虑到实际工程中因温控装置损坏导致反应器内水温降低,本试验还研究了UASB反应器内水温骤降对COD去除率的影响。研究发现,当反应器内水温由37℃骤降至30℃时,COD去除率逐渐降低,但随着反应时间的增长,COD去除率有上升趋势。水温由骤降30℃至20℃时,出水水质较差,COD去除率仅为60%左右。故采用UASB反应器处理DHA废水时,应控制容积负荷为8kgCOD/(m3·d),并保证反应器水温为30℃以上。试验采用MBR系统对DHA废水进行好氧处理。经调试,好氧生物系统容积负荷可达1.5kgCOD/(m3·d)。在容积负荷为1.5kgCOD/(m3·d),HRT为24h时,MBR膜出水水质良好,COD浓度为80mg/L左右,去除率大于94%;氨氮浓度为5mg/L以下,去除率为96%以上。通过实验室小试结果可知,采用“铁炭微电解—UASB—MBR”组合工艺可有效去除DHA废水中有机物浓度,出水水质稳定,满足《污水排入城镇下水道水质标准》(CJ 343-2010),可为DHA废水处理实际工程提供借鉴。
[Abstract]:DHA is a very beneficial unsaturated fatty acid to human cardiovascular system, nervous system and anti-inflammatory immune system. It is also an indispensable nutritional element for human health. A certain amount of high concentration refractory organic wastewater was produced in a series of DHA products produced by a certain biotechnology company in Jiangsu Province. The concentration of COD in the wastewater was 53000,54000mg / L Bod / L = 0.09 / 0. 1, and the biodegradability was extremely poor. In order to obtain the best operation parameters of DHA wastewater treatment, the combined process of "iron-carbon micro-electrolysis-UASB-MBR" was adopted to investigate the removal and variation of COD concentration in each system and combination process. Iron-carbon micro-electrolysis was used to pretreat DHA wastewater. According to the orthogonal test, the factors influencing the removal efficiency of COD in iron-carbon microelectrolysis reaction are the stirring intensity of reaction time at the pH value of iron-carbon ratio. According to the single factor optimization test, the optimum operating conditions were as follows: ph 3, reaction time 4 h, ratio of iron to carbon 3: 1, stirring intensity 300 r / min. Under the optimum operating conditions, the removal rate of COD from DHA wastewater by iron-carbon microelectrolysis is about 45%, the value of BOD5 / COD is increased from 0.1 to 0.31, which greatly improves the biochemical properties of DHA wastewater and creates good conditions for subsequent biochemical treatment. UASB reactor was used for anaerobic treatment of DHA wastewater. After 67 days of commissioning, the volumetric load of the reactor reached 8kgCOD/ (m ~ 3 d),) and maintained stable operation, and the COD removal rate of effluent was about 81% when 1500mg/L concentration was about. The effect of different volume loading on the removal efficiency of COD was studied. It was found that when the volumetric load was greater than 8kgCOD/ (m3 d), the removal rate of COD decreased obviously, and the effluent quality was very unstable. In addition, the effect of sudden drop of water temperature in UASB reactor on the removal rate of COD was also studied in view of the decrease of water temperature in the reactor due to the damage of temperature control device in practical engineering. It was found that the COD removal rate decreased gradually when the water temperature in the reactor dropped from 37 鈩，

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