Comparative Study On The Effect Of Aquatic Plants On The Treatment Of Breeding Wastewater

With the rapid development of livestock and poultry industry production,plenty of livestock and poultry excrement and various wastes emerge causing that the contradiction between the development of livestock and poultry industry and environmental pollution becomes increasingly prominent.The currently adopted treatment methods for breeding biogas slurry wastewater are numerous.Most of them are strengthened treatments of physical and chemical measures,which possess the problems of high cost and operation expense.However,utilizing plants to repair the pollutions is with advantages such as high efficiency,low investment,low operation expense and low maintenance technology.Therefore,the research on the decontamination effect of aquatic plants has favorable benefit for solving China’s water pollution problems.Based on the selecting requirements of ecological purification landscape plants and combined with Hunan local plant distribution characteristics as well as predecessors’ research achievements on breeding wastewater purified with plants,this research finally selects 6 types of emergent aquatic plants,namely Cyperus alternifolius,Thalia dealbata,Acorus calamus,Scirpus validus,Zizania latifolia and Typha orientalis,as the research object,and conducts analysis on the plant purification effect of single plant and plant combination under different concentration gradient as well as the growth adaptability and pollution tolerance of plants toward breeding biogas slurry wastewater.The research result is as follows:1.Comparative Analysis of Single Aquatic Plant Mode on Breeding Wastewater Purification Effect1.Under 3 types of different concentration gradients,it all reveals that Cyperus alternifolius and Acorus calamus possess the strongest adaptive capacity and the survival rates are both 100%;the second strong adaptive capacityis Scirpus validus,whose survival rates are both 100%under Concentration 2 and Concentration 3;the worst adaptive capacity is Typha orientalis,whose survival rate is only 60%under Concentration 3.2.Under different concentration gradients,the Cyperus alternifolius is with the strongest purification capacity on CODcr and NH3-N in breeding biogas slurry wastewater among the 6 types of plants.The removal rates on CODcr are separately 62.1%,69.8%and 7J.6%and the removal rates on NH3-N 69.8%,72.9%and 73.5%under Concentration 1,Concentration 2 and Concentration 3;Acorus calamus demonstrates better removal effect on TP,which are separately 58.1%,64.3%and 70.1%;when BOD5 in Concentration 1,Cyperus alternifolius possesses better removal effect on it and the removal rate is 47.1%;however,Acorus calamus possesses better effect in Concentration 2 and Concentration 3,and the removal rates are 60.5%and 61.1%;for the fecal coliform,Acorus calamus.possesses more obvious benefit.3.The botanical system has obvious purification effect on pollutions such as CODcr,NH3-N,TP,BOD5,pH and the fecal coliform compared with the blank control.The purification effects on various pollutions are all that Concentration 3 is better than Concentration 2 and Concentration 2 is better than Concentration 1;however,Cyperus alternifolius,Acorus calamus and Zizania latifolia demonstrate the best purification effect in Concentration 2 and the second purification effect is in Concentration 3.Ⅱ.Comparative Research of Combined Aquatic Plant Mode on Decontamination Effect1.For combined system,the combination of Cyperus alternifolius and Acorus calamus demonstrate the optimal effect on CODcr and NH3-N in the breeding biogas slurry wastewater;the removal rates are 83.4%and 80.88%;Acorus calamus combined with any one of the other five types of plants all possess obvious effect on TP degradation;Cyperus alternifolius combined with any one of the other five types of plants all possess higher removal rates on BOD5.Thalia dealbata and Typha orientalis possess obvious purification effect on the fecal coliform.However,Acorus calamus doesn’t reveal strong purification capacity among the combined system.2.Among the 6 types of plants,Cyperus alternifolius,Acorus calamus and Scirpus validus have sound growth status;although Acorus calamus has higher survival rate,it will produce the strong inhibitory effect toward Zizania latifolia and Typha orientalis;however,Scirpus validus is able to coexist with other plants friendly.3.The average plant height increment and biomass situation of Scirpus validus and Cyperus alternifolius are higher for single planting than those for combined planting.The rest 4 types of plants are with better effects in the combined system for they are enhanced to grow better.For N and P contents in the plants,Cyperus alternifolius and Acorus calamus possess higher contents due to possessing relatively larger biomass.