味精生产中离子交换废水的预处理技术研究

Pretreatment technology of ion exchange wastewater released from the production of monosodium L-glutamate

采用电化学法、吹脱法和化学沉淀法对味精废水中离子交换废水的预处理进行了试验研究。结果表明 :以铸铁屑为主的铁碳法 ,当HRT为 2h时 ,pH可从 1.97升至 4 .88,可大大减少后续中和吹氨所需石灰量 ,Fe-C还原对去除COD、氨氮和提高可生化性无明显效果。pH中和至 9.5～ 10 ,鼓气量在 10 0m3 /h左右 ,水温 5 5℃左右 ,经 8h ,可将原水NH3 -N从 12 0 0 0mg/L左右降至 4 0 0 0mg/L左右 ,脱除率 6 5 %以上。磷酸氨镁法去除废水中NH4+ -N ,在n(Mg2 + )∶n(PO43 -)∶n(NH4+ -N) =1∶1∶1(物质的量比 )时 ,随废水 pH升高 ,NH4+ -N去除率逐步增大 ,pH为 10时其去除率达到 5 4 %

Experiments have been conducted to pretreat the ion exchange wastewater (the main part of the Monosodium L-glutamate (MSG) wastewater) by means of Fe-C deoxidization to increase the pH and biodegradation, lime counteraction and aeration by air or chemical deposition to remove ammonia. The experiment results show that Fe-C deoxidization by the use of cast iron bits can increase the pH from 1.97 to 4.88, when the HRT is 2 h so that the lime quantity for ammonia removal can be reduced greatly.But there is little difference in the cost of pH adjust by Fe-C deoxidization and lime counteration,and no obvious effects are found for the removal of COD and ammonia, so does the increase of biodegradation. The influent ammonia can be reduced from 12 000 mg/L to 4 000 mg/L after 8 h reaction, and the removal rate can be above 65%, when the pH is 9.5～10; the air quantity is about 100 m 3/h; the wastewater temperature is heated to 55 ℃. The experimental result of ammonia removal by means of chemical deposition shows that, when n (Mg 2+ )∶ n (PO 4 3- )∶ n (NH 4 + -N)=1∶1∶1, ammonia removal rate increases with the increase of pH. When the pH is 10, the ammonia removal rate can reach 54%.