Treatment Effect Of Baiyangdian Reed On Wastewater From Duck Farm

The pollutants from the livestock and poultry breeding were becoming the third source of pollution after industrial effluents and domestic sewage. Due to the backwardness of harmless treatment and resource recycling of livestock feces, the disposal pollution such as livestock feces around the lake was one of the main sources of nitrogen and phosphorus pollution of water bodies. Reed wetlands could be understood as a kind of compound ecosystem of which the internal process had been controlled by water and its removal effect on pollutants was obvious. Therefore, the study of reed wetlands in Baiyangdian Lake in the treatment of wastewater from duck farm had very important practical significance.An indoor simulation experiment was conducted to investigate the purification regulation of reed wetlands ecosystem for treating wastewater. A field test was also conducted to study the changes of reed aboveground biomass and nitrogen and phosphorus content with different cutting times to probe opportune cutting time and protect Baiyangdian Lake ecosystem. The main conclusions were as follows:1. Under the irrigation conditions of low, medium, high concentration duck-manure wastewater, the reed biomass and plant height were all better than control group and the biomass gained significantly. The reed biomass had grown 36.1%,24.4%,24.3% respectively and the plant height had grown 24.3%,8.3%,5.0% separately.2. The average removal rate of total phosphorus in the duck-mature wastewater reached 98.79% at different times of reed ecosystem. The wastewater total phosphorus absorption of reed ecosystem accorded with the power function equation Y = C 0X ?b and the best absorption effect occurred when T=23℃. The biggest phosphorus environmental capacity of Baiyangdian Lake reed ecosystem was about 171.71t/a with optimum temperature, based on experiment results and local natual conditions.3. The COD removal rate and rate amount of reed ecosystem increased with the increase of duck-mature wastewater concentration. The purification effect was high concentration>medium concentration>low concentration. The COD purification process of reed ecosystem could be shown by the first order dynamic equation. Under medium concentration treatment condition, the k value reached maximum with T=27.2℃when the COD purification effect reached the best. According it the biggest COD environmental capacity of Baiyangdian Lake reed ecosystem was about 1655.22t/a with the optimum temperature.4. The purification of ammonia nitrogen in reed ecosystem was complex. Although fitting equations of different periods and different treatments correlated well, they couldn't be expressed by a compositive purification model.5. The influence of irrigating duck-mature wastewater on the soil total nitrogen content was mainly concentrated in the 0-20cm soil surface. Under low, medium, high concentration treatment conditions, compared with control group, the nitrogen content of 0-20cm soil surface had increased 7.87%, 18.64% and 29.66% respectively. The reed nitrogen content had changed little with irrigation condition. Reed aboveground total phosphorus content increased gradually with the increase of duck-mature wastewater concentration. Under medium and high concentration conditions, the total phosphorus had increased 28.79% and 40.91% than control group, showing significant difference.6. Opportune cutting time was helpful to regrow new reed seedlings. Single-stubble cutting and multi-stubble cutting with different periods resulted in different reed aboveground biomass and total nitrogen and total phosphorus content.