| The kitchen waste fermentation wastewater(KWFW)had low COD/N and high ammonium.Therefore,there were several problems treating KWFW such as insufficient carbon source for denitrification,high membrane cost for refractory organic,complicated operation and management.On the basis of our early research on partial nitrification and denitrification process(PND)treating KWFW,in this study,the electrolysis assisted bio-system for KWFW advanced treatment was developed with the PND effluent(mainly NO2--N and refractory organic matter)as research object,to realize shortcut autotrophic denitrification and refractory organic matter removal simultaneously and efficiently.This study explored the effects of filler,electrode types and microbial growth mode on the construction of electrolysis assisted bio-system.And the influences of nitrogen load,current and temperature on nitrogen removal performance of electrolysis assisted shortcut autotrophic denitrification system(e-SAD)were investigated,and key operation parameters were obtained.This study investigated the nitrogen and refractory organic matter simultaneous removal performance of electrolysis assisted bio-system for KWFW advanced treatment,and obtained optimal condition for meeting emission standards.Furthermore,the microbial structure and dominant functional bacteria in the system were analyzed by 16S r RNA high-throughput sequencing technology,revealing the microbial mechanism of the system.The degradation of refractory organic compounds was analyzed by three-dimensional excitation emission matrix fluorescence spectroscopy(3D-EEM).The main conclusions were as follows:The types of filler and electrode had significant influences on the construction of e-SAD.Natural fiber(density 40 g/l)and iron anode were suitable.Under the condition of temperature of 24±1°C and without carbon source,the system was constructed successfully after 12 days operation,and the NO2--N and total nitrogen(TN)average removal efficiencies were 99.78%and 94.39%,respectively,which was 4.23%higher than TN of the combined fiber system,and 4.84%higher than graphite anode system.The16S r RNA high throughput sequencing results showed that autohydrogenotrophic and iron-dependent denitrification were main nitrogen removal paths with the functional bacteria,Aquihabitans,Thauera and Proteiniclasticum.In addition,the growth mode of microbial had a significant influence on the construction of electrolysis assisted KWFW advanced treatment bio-system.The average removal efficiencies of NO2--N,TN,chroma,UV254 and COD were 99.97%,84.30%,96.13%,73.10%and 62.09%,respectively,higher than that of biofilm system.Nitrogen load,current and temperature had significant effects on nitrogen removal performance of e-PD.With the NO2--N load increasing from 0.05 to 0.10 kg N/(m3·d),the TN average removal load increased from 0.047 to 0.077 kg N/(m3·d).With the increase of NO2--N load,the nitrogen removal capacity of the system increased.When the current intensity decreased from 50 to 10 m A,the TN removal efficiency decreased gradually.The appropriate current intensity was 30 m A,and the TN removal efficiency was 88.75%.The temperature increasing from 35 to 43°C,the TN removal efficiency decreased from 87.35%to 82.41%,and then decreased to 72.80%when temperature increased to 45°C.The e-PD had resistance to medium and high temperature,and the optimal temperature is 35°C.When NO2--N load increased from 0.05 kg to 0.10 kg N/(m3·d),the total relative abundance of denitrifying bacteria increased from 20.51%to66.25%,and the dominant denitrifying bacteria changed from Aquihabitans,Thauera and Proteiniclasticum to Thauera and Pseudomonas.When the current decreased from 50 to20 m A,the dominant functional bacteria in the system were Thauera and Acetoanaerobium,and autotrophic denitrification was main nitrogen removal pathway.Current and pollutants load had significant effects on nitrogen and organic matter simultaneous removal performance of electrolysis assisted bio-system for KWFW advanced treatment.The optimum current intensity was 60 m A,and the NO2--N,TN,chroma,UV254 and COD average removal efficiencies were 99.79%,84.96%,98.59%,74.31%and 67.36%,respectively,and the total cumulative fluorescence intensity of dissolved organic matter and that of refractory organic matter decreased by 38.69%and42.58%,respectively,and the proportion of refractory organic matter decreased by 4.70%.Electrocoagulation was the main pathway to remove refractory organics.When the nitrogen,COD loads were 0.018?0.021 kg N/(m3·d),0.146?0.209 kg COD/(m3·d),the average removal efficiencies of NO2--N,TN,chroma,UV254 and COD were 99.78%,85.80%,98.15%,79.53%,and 80.42%,respectively.And the total cumulative fluorescence intensity of dissolved organic matter and that of refractory organic matter decreased by 39.75%and 44.96%.Under the optimal condition,the NH4+-N,TN,COD and chroma average concentrations in effluent of electrolysis assisted bio-system for KWFW advanced treatment were 8.01±1.89,8.48±1.67,91±6 mg/L,and 10±3,respectively,meeting the"Regulations in Table 2"of"Pollution Control Standards for Domestic Waste Landfill Sites"(GB 16889-2008). |
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