Study On The Feasibility And Resource Utilization Of Wastewater Treatment Using Cladocerans

Along with the development of intensive pig industry, swine wastewater isbecoming a serious environmental concern. On the other hand, the amount of nutrientssuch as nitrogen and phosphorus contained in the swine wastewater has high valuable toresource utilization. Therefore, how to recycle the nutrients and remit the environmentalimpacts of swine wastewater has become an international research topic for many years.Cladoceras, being one class of planktonic crustacean, are widely distributed in the freshwater, especially outbreaks of cladoceras are frequently observed in eutrophic waterbody. On the other hand, they are used as feed in aquaculture widely due to their richnutrition. Hence, to reduce the impacts of swine wastewater on environment as well asimproving the survival rate and seeding quality of loach and eel for artificial breeding,the objectives of this article mainly discussed the feasibility of swine wastewaterpurification using cladoceras and the effects of cladoceras on the seedlings ofMissgurnus arguillicaudatus and Monopterus albus. The major results are showed asfollows:(1) A total of22species in10genera of5families were identified by the annualdynamics of cladoceras community structure in the swine wastewater recycling system.There were7dominant species in different seasons. Daphnia pulex, Moina macrocopa,and Ceriodaphnia cornuta were selected as the following test objects basing onanalyzing the characteristics of the dominant species.(2) The appropriate initial ammonium nitrogen concentration of inoculum wasdetermined as20~25mg/L according to the response study of Moina macrocopa underdifferent concentrations of swine wastewater. Then we studied the population changing and wastewater purification effect using these test objects with25mg-N/L ofammonium. The results showed that the highest densities peak was M. Macrocopa(1981.3±106.5ind/L), the second one was C. cornutathree (1665.3±104.1ind/L), andthe third one was D. pulex (1476.0±46.1ind/L). The net removal rate of TN was1.49%,2.19%and2.10%while the net removal rate of TP was4.18%,9.09%and8.22%in turn.According to the purification effect or the reutilization ability of swine wastewater, M.macrocopa and D. Pulex were more useful.(3) Based on the above research results, the studies on the feasibility of theaforementioned cladoceras used as initial feed of loach and eel were conductedrespectively. The results showed that the survival rates of loach fries using C. Cornutaand D. Pulex as initial feed were59.00%and38.67%respectively, which improved32%and11.67%compared with the control group (the cooked egg yolk). The totallength and weight of loach fries were also both significantly higher than the controlgroup.On the other hand, the survival rate of eel fries reached100%when the testcladoceras used as initial feed, which increased11.11%and3.37%compared with thecontrol treatments of the cooked egg yolk and eel compound feed, respectively. And thequalities of eel fries were significantly greater than the control groups.