Study On Building And Operation Effect Of Recirculating Aquaculture System Based On Hydroxyl Radical

With the continuous expansion of the saline aquiculture in China,saline aquiculture industry has become one of the significant pillar industries in Chinese coastal areas.Recirculating aquiaculture system,with a core technology of water treatment and system,was considered as the future development direction.While the adverse effect of the traditional treatment technology such as,long starting time,poor treatment efficiency and frequently occurrence of disease,have suggested that effective method should be promoted to solve these problems.In this paper,we built a hydroxyl radical(·OH)recalculating aquaculture system by using the ·OH prepared from ionization.discharge by atmospheric pressure and[Epinephelu.s lanceolatu(♂)×Epinephelus fuscoguttatus(♀)]used as the research object.We set the operation parameters of the·OH processing system,performed the short-term experiment and explored the operating conditions by applying this system into practical use.The main research results are shown as follows:(1）With a strong ionization discharge,high concentration oxygen active species such as O2+.0(1D),O,O2,O2(a1△g)were produced and then transferred into a gas/liquid injector to efficiently form oxygen radical solution such as ·OH.H2O2,HO3·and)2＋(H2O)to treat aquiaculture seawater in fish tanks.Build ·OH recirculating aquaculture system based on this:fish tank→foam separator→water tank 1→activated carbon filte→water tarnk 2→·OH equipment→fish tank.(2)Completed the fitting of the decay curve over time that setting concentration of the TRO is 0.2.0.5 and 1.0mg/L.The decay kinetics constant k was 10.4185-21.59224 h-1,2.63975-3.35067 h-1 and 0.46985-1.98974 h-1 respectively.The ·OH solution injection method is to extract 1/2 water from fish tank to reinjection which can reach the set value at 30 min and maintain stability within 30-90 min.The different TRO sampling points of the fish tank are respectively 4.41-16.82%,7.11-14.75%and 3.85-12.30%.The stability of-OH treatment was realized.(3)The experiment of of culturing[Epinephelus lanceolatu(♂)× Epinephelus fuscoguttatus(♀)]was performed when set TRO as 1.0,0.5 and 0.2 mg/L.The results showed that the inactivating rate of bacteria and other harmful bacteria was found 100%after ·OH treatment And the removal rate of nitrite were 80%-100%respectively.The dissolved oxygen increased by 34.8%、52.1%and 78.0%respectively.At the same time,the growth of fish was good,with the increase rate of 2.25%,2.88%and 2.24%and specific growth rate was 0.36,0.40 and 0.31%/d respectively.The ammonia nitrogen and nitrite in 7 days was less than 0.1 mg/L by ·OH treatment.The water quality in meets the national regulation "fishery water quality standard"(GB11607-1989).(4)·OH technology was used for treatment on factory recalculating aquaculture water.By sampling and analysis of Xiaodeng Island recirculating aquaculture system effluent,the results showed that the water turbidity,color,CODMn,TAN and nitrite decreased by 22.9%,46.2%,13.2%,8.8%and 97.7%respectively with TRO 0.51 mg/L after 9.8 s.The dissolved oxygen increased 104.2%and without the generation of bromate.Compared to UV disinfection whose inactivating rate was 76.9%and 47.1%,the total nurmber of colonies and total coliform bacteria inactivating rate both achieved 100%under the same condition.In addition,the terminal water quality in ·OH system meets the national regulation "fishery water quality standard"(GB11607-1989).The effect of ·OH treatment on factory recirculation seawater is remarkable.In summary,this paper constructed a ·OH recirculating aquaculture system,which can rapidly and effectively kill the harmful pathogenic microorganisms、oxidative degradation of target pollutants while no harmful disinfection by-products generation and protect the healthy growth of fishes at the same time.This system will provide a creative method for advanced treatment of recirculating aquaculture seawater.It can be used in the factory seawater aquaculture industry.