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Inactivation of phosphorus from contaminated sediment of Dianchi Lake when treated with alum under different pH conditions and modified by clay mineral

摘要：采用铝酸钠和石灰为pH缓冲剂,并用粘土矿物对硫酸铝进行改良,研究不同硫酸铝剂量下对滇池污染底泥磷钝化的效果.结果表明,钝化剂对底泥磷的钝化效果具有时效性.以质量比Al:铝酸钠=1:3加入pH缓冲剂且铝剂量为4.95g·m^-2时,只能对底泥中磷起到短期的钝化作用,39d后底泥中磷即大量释放.以质量比Al:氢氧化钙=1:4加入pH缓冲剂且铝剂量为19.8g·m^-2时,142d内能稳定地保持对DIP、TPT的良好钝化作用,对DIP、TP释放的抑制率分别为88.9%和86.2%.加入适量的粘土矿物改良硫酸铝后可增强其钝化效果,硫酸铝的剂量为4.95g·m^-2时,以质量比Al:粘土矿物=1:0.5改良硫酸铝,142d内对DIP、TP抑制率分别为61.1%和86.9%.所有实验钝化剂方案在30d时Al³⁺浓度均小于0.05mg·L^-1,不会对水生生物造成毒害.

Abstract：Several dosages of alum buffered by sodium aluminate and lime were tested for their abilities to inactivate the phosphorus in contaminated sediments from Lake Dianchi.Alum modified by clay mineral was also tested to find the optimal dosage and long-term phosphorus inactivation effects.The experimental results revealed that phosphorus inactivation changed over time.When using sodium aluminate as pHbuffer,an alum dosage of 4.95 g·m^-2 with addition of 1:3 Al:sodium aluminate by mass was effective for phosphorus inactivation only for a short time and an obvious release of phosphorus occurred after 39 days.When using lime as pHbuffer,an alum dosage of 19.8 g·m^-2 with addition of 1:4 lime Al:lime by mass could inactivate sediment phosphorus effectively even after 142 days,with DIPand TPsuppression efficiencies of 88.9% and 86.2%,respectively.Modification of alum with specific clay mineral increased the inactivation effectiveness.Adosage of 4.95 g·m^-2 alum modified by clay mineral with mass ratio of Al:clay mineral=1:0.5 had DIPand TPsuppression efficiencies of 61.1% and 86.9% respectively after 142 days.Alum modified by clay mineral formed a close-grained floc blanket covering the sediment surface.At 30 days,the concentration of residual aluminium in all inactivator addition groups was lower than 0.5 mg·L^-1,which is the safe upper limit for aquatic organisms.