Abstract: In order to carry out research on discharge technology of pond aquaculture wastewater up to the standard,an aquaculture wastewater treatment system (AWTS)was established at a surface area ratio of culture pond to AWTS=9.8∶1.The AWTS was made up of a surface flow wetland (SFW)in which reed Phragmitescommunis,or cattail Typhaorientalis was planted at initial density of 15 individuals/m2 in March,or water chestnut Trapabispinosa was planted at initial density of 1.2 individuals/m2 in February;aquatic animal purification pond (PP1)in which mullet Lizahaematocheila was reared at stocking density of 0.39 individuals/m2 in March,polycultured with a few of black carp Mylopharyngodonpiceus,silver carp Hypophthalmichthysmolitrix and bighead carp Aristichthysnobilis,and aquatic plant purification pond (PP2)in which water hyacinth Eichorniacrassipes was planted in May and water spinach Ipomoeaaquatica was planted in August,polycultured with a few of black carp,silver carp and bighead carp with an area ratio of SFW∶PP1∶PP2=1∶4.5∶3.6.During the test period,the total nitrogen (TN)and total phosphorus (TP)discharged from the wastewater of 13 culture ponds (5 hm2)were monitored between the AWTS and the aquaculture ponds.The results showed that TN concentration was shown to be (2.025±1.031)mg/L in the inlet of the AWTS,and the discharge TN concentration of (1.323±0.427)mg/L after treatment,with average removal rate of 34.67% in two years from 2019 to 2020.The inlet TP concentration was found to be (0.627±0.734)mg/L,and the discharge TP concentration (0.427±0.369)mg/L,with the average removal of 31.89%.There was remarkable purification effect of TN and TP in the AWTS,with the removal of TN and TP at all levels along the system being conformed to the first-order dynamic removal model.The removal rates of TN and TP were increased step by step when the aquaculture wastewater flowed through the surface flow wetland,the PP1 and PP2.It was found that the purification pond dominated by aquatic animal had significant purification effects on TN,and the purification ponds combined with multiple aquatic plants had significant purification effects on TN and TP.With the extension of seasons,the AWTS still maintained a good purification effect on higher TN and TP.The aquatic plants purification pond played a key role in the purification of TN and TP in autumn.
2022, Vol. 37 
