污泥掺烧过程中Cl/S/P/矿物质的热交互作用对Cd迁移转化行为的影响

采用化学热力学平衡分析方法,应用污泥实测数据模拟计算了污泥掺烧过程中Cl/S/P与矿物质的交互作用,重点模拟研究了Cl/S/P/矿物质交互体系对Cd迁移转化的影响.研究结果表明,污泥掺烧过程含Cl、S及P逸出气体以HCl(g)、SO_2(g)及(P_2O_5)_2(g)形式排放.污泥掺烧含有CaO-SiO_2-Al_2O_3体系中,CaO可以抑制S以SO_2(g)释放,而SiO_2及Al_2O_3对SO_2(g)逸出有促进作用,同时CaO及Al_2O_3可以抑制P的挥发.污泥掺烧过程中SiO_2及Al_2O_3对Cd挥发都有一定抑制作用,但CaO及Fe_2O_3对Cd基本无影响;当Cl存在时,Ti O2和SiO_2对Cd吸附作用减弱,并使Al_2O_3吸附剂失效;当S存在时,可导致吸附剂对Cd中毒,而P可导致Al_2O_3吸附剂失效;Cl-S-P耦合体系中,单一矿物质对Cd迁移转化影响主要受Cl和S控制.SiO_2+CaO+Al_2O_3共存体系中,Cl的存在可导致固体吸附剂SiO_2和Al_2O_3失效;S、S+Cl、S+P、S+Cl+P的存在受控元素为S,并且可以抑制Cd的挥发;P、Cl+P的存在对Cd影响受控元素为Cl,可促进Cd挥发.

Effects of the interactions of chlorine, sulfur, phosphorus and minerals during sewage sludge co-incineration on the migration and transformation of Cd

Thermodynamic equilibrium was calculated to reveal the partitioning of the conditioners and their emissions during sewage sludge incineration. Profiles of both composition of sewage sludge and various combustion conditions were applied in simulations. Effects of co-existence of FeCl₃ and CaO on the migration of heavy metals were also in considerations. Results show that elements of Cl, S, and P emitted in the form of HCl (g) and SO₂ (g) and (P₂O₅) ₂ (g) during the mixed of sludge, respectively. CaO inhibited SO₂ in the mixed system containing CaO-SiO₂-Al₂O₃. On the other hand, both SiO₂ and Al₂O₃ additives can enhance the SO₂ (g) emission. At the same time, CaO and Al₂O₃ controlled the P volatilization. In the process of the mixed, the volatility of Cd was inhibited by both SiO₂ and Al₂O₃, but CaO and Fe₂O₃. Thus, adsorption of Cd caused by both TiO₂ and SiO₂ decreased when Cl existed, and the adsorption ability of Al₂O₃. In S, adsorbents were poisoned by Cd, and then, preduced the adsorption ability of Al₂O₃. In the Cl-S-P system, effect of a single mineral on Cd migration was mainly controlled by Cl and S. In the SiO₂+CaO+Al₂O₃ coexisted system, Cl disabled the adsorption efficiency of solid adsorbents such SiO₂ and Al₂O₃. Nevertheless, S dominated the reactions in the existence of S, S+Cl, S+P, S+Cl+P system, and it also restrain the volatilization of Cd. Besides, Cl promoted the volatilization of Cd in the existence of P and Cl+P environments.