碱度及外投碳源浓度对好氧颗粒污泥脱氮效果影响

Effects of alkalinity and external carbon source concentration on denitrification efficiency of aerobic granular sludge

为实现稀土矿山废水高效脱氮,探索了不同碱度和外投碳源下好氧颗粒污泥(AGS)对模拟离子型稀土矿山废水的脱氮效果。当水中碱度≤2 mmol/L时,pH与碱度近似呈线性关系,当水中碱度>2 mmol/L后pH几乎不再变化。硝化反应会消耗大量碱度,进而影响AGS的硝化效果及硝化反应的持续性。随着碱度的增大(2~13 mmol/L),硝化液出水pH呈增大趋势(6.2~8.4),氨氮呈减小趋势(79.2~19.2 mg/L),硝化反应持续时间延长(50~150 min)。当碱度为9.5 mmol/L时,反应前后pH保持在8以上,氨氮去除率达到最大值(80.9%),硝化反应可持续140min,更高的碱度并不会进一步提高氨氮去除率。外投碳源会导致硝化液pH升高并可强化AGS的反硝化效果,但当外投碳源质量浓度大于280mg/L(以乙酸钠的化学需氧量计)时,总无机氮(TIN)的去除率约为71.6%。碱度和外投碳源对AGS的同步硝化反硝化效果有重要影响,当碳源质量浓度和碱度分别在280 mg/L和8 mmol/L以上时,TIN的去除率大于85%。AGS的内源硝化-反硝化脱氮能力一般,但与外源硝化-反硝化相耦合可降低外投碳源量,具有较好的节能降耗潜力。

To achieve efficient nitrogen removal of rare earth mine wastewater,effects of alkalinity and external carbon sources on denitrification of simulated ionic rare earth mine wastewater by aerobic granular sludge(AGS)were explored.When alkalinity of the solution was less than 2 mmol/L,pH and alkalinity showed an approximately linear relationship,while alkalinity was larger than 2 mmol/L,pH was almost unchangeable.Nitrification would consume a large amount of alkalinity,which affected the ammonia nitrogen removal efficiency of AGS and the sustainability of nitrification reaction.With the increase of alkalinity(2~13 mmol/L),effluent p H of the nitrification solution showed an increasing trend(6.2~8.4),effluent ammonia nitrogen showed a decreasing trend(79.2~19.2 mg/L),and duration of nitrification reaction extended from 50 to 150 min.When alkalinity was 9.5 mmol/L,pH before and after the reaction was always larger than 8,the removal rate of ammonia nitrogen reached the maximum value of 80.9%,and the nitrification reaction lasted for 140 min.A higher alkalinity would not further improve the removal rate of ammonia nitrogen.The external carbon source would lead to the increase of the p H of the nitrification solution and enhance the denitrification efficiency of AGS.However,when the mass concentration of external carbon source(calculated by chemical oxygen demand of sodium acetate)was greater than 280 mg/L,the removal rate of total inorganic nitrogen(TIN)was about 71.6%.Alkalinity and external carbon source had an important influence on simultaneous nitrification and denitrification performance of AGS.When the mass concentration of carbon source and alkalinity were larger than 280 mg/L and 8 mmol/L,the removal rate of TIN was larger than 85%.Although the endogenous nitrification and denitrification capacity of AGS was limited,the dosage of external carbon source could be reduced when it coupled with exogenous nitrification and denitrification,indicating that the coupling denitrification had a good potential of saving energy and reducing carbon source consumption.