Research On Treatment Of Domestic Sewage By Aquatic Vegetable Wetland In Rural Area

Based on the low content of heavy metals and low level organic matter in rural domestic sewage,research on purification of rural sewage in aquatic vegetable wetland was studied.The effects of stroma,aquatic vegetable,season and hydraulic loads on constructed wetland were investigated.Moreover,the safety of water spinach and cress was evaluated.The results are as follows:1.The adsorption capacity of waste permeable floor tiles,gravel and gallet on ammonia nitrogen is as follows: Waste permeable floor tiles > gravel > gallet.The adsorption capacity of each filler on phosphorus is as follows: Waste permeable floor tiles > gravel > gallet.Adsorption effect of waste permeable floor tiles on ammonia and phosphorus was the best,and there was a lower risk to form secondary pollution.Therefore,the waste permeable floor tiles was chosen as the stroma of the constructed wetland.2.The celery was selected as the aquatic vegetable of the constructed wetland in the winter,and the water spinach was selected as the aquatic vegetable of the constructed wetland in the summer.The water quality of CODcr and ammonia nitrogen and total phosphorus in the constructed wetland reached the two grade standard of the pollutant discharge standard of the urban sewage treatment plant(GB 18918-2002).3.When the hydraulic load was 971.66mm/d,the constructed wetland had the best effect on the removal of CODcr.When the hydraulic load was 388.66mm/d,the constructed wetland had the best effect on the removal of ammonia nitrogen and TP.Therefore,the hydraulic load is determined to be 388.66mm/d,which is beneficial to remove polluted materials from aquatic vegetable of constructed wetland.4.Celery and spinach grew in a good condition,and the average height of them were 48.93 cm and 48.32 cm.The area yield were 23.83kg/m2 and 30.05kg/m2.Compared with other vegetables,celery and spinach were more economical inproduction.The contents of heavy medals in vegetables before and after the experiment were not over standard.Consequently,all the vegetables were safe to eat.