适宜处理分散性生活污水的人工湿地除磷填料的筛选及改性

为提高人工湿地除磷效能,从沸石、陶粒、萤石、膨胀蛭石、石灰石、麦饭石、火山岩、牡蛎壳、钢渣和废砖块这10种具有较高磷素饱和吸附量的填料中,筛选出钢渣、沸石和石灰石3种适宜处理分散性生活污水的人工湿地填料,并分别使用不同浓度梯度的酸(碱)、盐对3种填料进行改性,以增强其除磷能力。研究结果表明,钢渣、沸石和石灰石分别经2 mol/L AlCl3、2 mol/L NaOH及2 mol/L AlCl3、0.5 mol/L AlCl3溶液改性后,磷素吸附量达到最高值(0.272、0.0801和0.351 mg/g),而双常数方程能更好地描述优选填料对生活污水中磷的吸附动力学过程,综合考虑填料的吸附效果、成本及来源,改性石灰石是人工湿地处理分散性生活污水时较为理想的除磷填料;此外,填料经铝改后,氮磷吸附效果普遍优于其他改性条件,且Al-P有利于植物直接吸收利用,含铝废水来源广泛,故利用铝改液处理人工湿地填料具有较高的应用推广价值。

Screening and modifying of suitable substrates to improve phosphorus removal capability of constructed wetlands for decentralized sewage treatment

To improve the phosphorus removal capability of constructed wetlands, limestone, zeolite and slag were selected from 10 substrates with higher phosphorus adsorption capabilities, which were the zeolite, ceramic, fluorite, expanded vermiculite, limestone, medical stone, volcanic rock, oyster shells, slag, broken bricks. The three suitable substrates were modified by different concentrations of acid (alkali), aluminum, calcium solutions to enhance their phosphorus removal capability. The results showed that slag, zeolite, limestone reached the highest phosphorus removal capability (0.272, 0.0801 and 0.351 mg/g), modified by 2 mol/L AlCl₃, 2 mol/L NaOH and 2 mol/L AlCl₃, 0.5 mol/L AlCl₃, and dual constant equation was the best model to describe the phosphorous adsorption characteristics of these substrates in sewage. Simultaneously, considering the removal effect, cost and resource of substrates, the modified limestone is the suitable substrate to improve phosphorus removal capability of constructed wetlands for decentralized sewage treatment. In addition, the selected substrates modified by widely used aluminum solution have higher nitrogen and phosphorus adsorption capabilities than other modified substrates, while Al-P is easily absorbed to plants. Therefore, aluminum solution is suggested to modify the substrates in constructed wetlands.