味精离交废水混凝沉淀除硫技术的研究

通过正交试验,系统地考察了多个因素对味精离交废水混凝沉淀除硫的影响,获得了除硫效果达最优水平的组合条件,即原废水的浓度(35.526 g/L),Ca2+投加量为SO42-含量的1.5倍,pH为3.2,不加混凝剂聚丙烯酰胺或聚合氯化铝;确定了混凝沉淀法中各因素对除硫效果的影响程度由大到小依次为:废水浓度、沉淀剂(CaCl2)的投加量、废水pH值、混凝剂的投加方式和投加量.根据原废水中的SO42-浓度等摩尔投加Ca2+(CaCl2),经过15 min后,SO42-去除率达90%,能够满足厌氧生物处理的要求;沉淀过程具有浓悬浮液沉淀的特点,清水区和悬浮物区分界面明显;沉降24 h后生成的沉淀物含水率为81.4%.若将原废水稀释,在同样的条件下,SO42-去除率降低,沉淀物含水率升高,颗粒物沉降性变差,上清液浑浊.故对味精废水的沉淀除硫处理宜在高浓度下进行.

Sulfate removal from monosodium L-glutamate wastewater with flocculation and precipitation process

The sulfate in the ion-exchange wastewater from monosodium L-glutamate production was removed with flocculation and precipitation process.The orthogonal experiment showed that the optimum levels of influence factors were as follows: original concentration(SO_4~(2-) 35.526 g/L),pH 3.2,Ca~(2+)/SO~(2-) ratio of 1.5,addition of neither poly aluminium chloride nor polyacrylamide.The contribution of influence factors to sulfate removal was,in decreasing order,wastewater concentration,Ca~(2+) dosage,pH,dosing sequence and coagulant dosage.On the condition that the Ca~(2+) dosage was equal to the SO_4~(2-) amount in the original wastewater,the sulfate removal efficiency was above 90% and the supernatant was clean after reaction for 15 min.The water content of the CaSO_4 sediment was about(81.4%) after being settled for 24 h.It is highly recommended to remove the sulfate from the wastewater at its original concentration rather than using the diluted wastewater,because the sulfate removal efficiency was lower,the supernatant was turbid and the water content of the CaSO_4 sediment was higher if the diluted wastewater was used.