Efficient Vertical Flow Constructed Wetland Sewage Treatment System Practice

According to current research of Constructed Wetlands wastewater treatment system, this paper does some research with Shiyan Constructed wetland and Gankeng Constructed wetland, including pre-treatment system, different substrate, different plants, different depths of substrate, recycle system, benefits analysis and provides constructive views to how to manage and maintenance middle or large scale Vertical Flow Constructed wetlands. Main results as bellow:(1) Pre-treatment system is a must part. The treatment performance of hydrolyzed-acid pond with stuff is good, reduction of CODcr, BOD5 by 30% - 53.5%, 32.5%~66% respectively.( 2 ) There are many factors affecting treatment performance of Vertical Flow Constructed Wetland, including pre-treatment system, hydraulic loading, depths of substrate, and kinds of plant.( 3 ) This study applies four new substrate, all of them have better performance than normal sand. There are slightly different removal rate of CODcr, BOD5 with different substrate. But the different removal rate of PO4-P, NH3-N is significant. So, different pollutant resources should use different substrate. The order of whole performance, Microorganism substrate performed better than Compound substrate with Fe and C, Compound substrate with Fe and C performed better than Limestone substrate, Limestone substrate performed better than biological Ca substrate.(4) Reduction of pollutant with Phragmites and Cyperus are very effective, Thalia and Pemnistum also have good reduction performance with CODcr, BOD5, PO4-P, but low performance forNH3-N. So different pollutant resources should use different plants.(5 ) The study compared treatment performance with three different depths. The order of reduction percentage as follow:PO4-P, NH3-N: 75cm>60cm>45cm, CODcr, BOD5: 60cm>70cm>45cm.(6) There is good performance of recycle system, CODcr, BOD5, P04-P, NH3-N can have large amount reduction by recycle system.(7) Vertical flow Constructed Wetlands provide many benefits, including low investment, cheap operational fee, high treatment efficiencies, and landscaping.This research makes breakthrough in scale of treatment system, combined treatment process and substrate, it also provides theory and experiences and promotes ecological treatment process, to some extent.