Research on the application of the modified aquatic mat pond and integrated vertical-flow constructed wetland coupling process based on luffa sponges for micro-polluted water treatment

Abstract

This paper presents a scientific performance study of the application of the modified aquatic mat pond (MAMP)-integrated vertical-flow constructed wetland (IVCW) coupling process for treating micro-polluted river water using luffa sponge material. In addition, the surface modifications of luffa sponge were investigated. The results showed that luffa sponge functioned well in a bench scale experiment and in a demonstration project, and the main effluent water indexes reached the class IV standard defined by the surface water quality standard of China (GB3838-2002). However, natural luffa sponge is easily hydrolyzed and should be replaced at regular intervals. A microwave-enhanced KH550 (Silane coupling agent gamma-aminopropyltriethoxysilane) coupling method for modifying luffa sponges were performed to reduce the water absorption rate and prolong the engineering service time of the sponge. The results showed that the water absorption rate of the tested luffa sponge fibers was reduced to 22.39% after the fourth set of modifications, and an orthogonal test revealed that the priority order for the factors that affected the modification process was KH550 concentration >microwave reaction time >NAOH concentration > soaking time. The optimal set of modification conditions for luffa sponge fibers was 2% (w/w) NAOH, 1% (w/w) KH550, 30 min of soaking and 180 s of microwave treatment.