Study On Mechanism Of The Treatment To Eutrophic Water Body By Sized Grassland And Equipment

Nowadays, with the water pollution problems becoming more and more serious, the eutrophic problem of the water body becomes more and more prominent. Industrial aquaculture especially in special animal breeding has a problem of how to dispose the high concentrated organic and eutrophic wastewater, which has restricted the further development of the aquaculture industry. How to make use of the nutrient substances of the aquaculture wastewater efficiently, how to reuse the aquaculture wastewater economically and how to solve the problem of eutrophication are in great urgency.The turtle-breeding wastewater of the high concentrated NH4+-N was treated by ryegrass (Lolium perenne) which was planted in the constructed tanks by means of substratum-cultivation. The feasibility of the utilization of aquaculture wastewater in reasonable way, the purification efficiency of the ryegrass water recycling substratum system to the turtle-breeding wastewater and the parameters of the engineering design in hydraulics were discussed. The results are as follows:(1) In the experiment of the static ryegrass hydroponic cultivation, the ryegrass appeared a good adaptability to the turtle-breeding wastewater. The ryegrass can adapt itself well to the turtle-breeding wastewater if only the wastewater concentration of CODcr, TN, TP, NH4+-N were controlled around 300mg/L, 110mg/L, 22 mg/L, 60 mg/L, respectively. When the ryegrass was planted in 140g/m2, the removal efficiencies of CODCr, TN, TP, NH4+-N were beyond 80%, 30%, 50%, 30%, respectively. It can increase the removal efficiency of the nutrient substance by increasing the planting density suitably. The technology of ryegrass hydroponic cultivation can be directly applied to the eutrophic water body with the engineering enlargement. But the design parameters and the purification efficiency need to be tested in practical engineering.(2) The ryegrass water recycling substratum system for treatment to the turtle-breeding wastewater was full feasible. Planted on the substratum and supporter whichintegrated the coarse paper and non-woven fabric, the ryegrass can efficiently absorbthe nutrient substance in the water as the nutrient source for self-growing. It resolved not only the eutrophic problem of water body, but also the problem of the nutrient source for the ryegrass. Meanwhile the purpose of recycling utilization as ecosystem was realized. Designed the tank 750cm X 60cm in length to width, seeded the ryegrass in 30g/m2 and controlled the HRT for 23.5 hours, inflow for 0.085m3 per hour and batch inflow time 10min per hour, the system had high removal efficiency of nutrient substance to the turtle-breeding wastewater. After 22 days, the removal efficiency of CODcr, TN, NH4+-N were beyond 86%, 50%, 90%, respectively. The engineering design parameters to CODcr, TN, NH4+-N were 0.66mg/L/m2 .d, 0.23 mg/L/m2.d and 0.29 mg/L/m . d, respectively. These are good practical parameters for engineering enlargement and application.(3) This engineering design was quite simple and the cost for disposal was low. It was convenient for management and had a strong practicability, especially for purifying the eutrophic water body of aquaculture.(4) In this experiment the turtle-breeding wastewater was treated by Lolium pererme and the treatment efficiency was good. Because Lolium multiflorum Lam. had a resemble character in biology with Lolium pererme, the Lolium pererme can also be replaced with Lolium multiflorum Lam in the system for treatment to the aquaculture wastewater.