Performances Of Sequential Vertical Flow Trickling Filter And Horizontal Flow Multi-soil-layering Reactor For Treatment Of Domestic Wastewater With Surfactant

Domestic wastewater pollution in rural China has become serious environmental challenge because of lacking applicable wastewater management.In this study,small footprint,low investment,low energy consumption device was use d to treat simulated wastewater with sodium dodecylbenzene sulfonate（SDBS）.The device was composed of vertical flow trickling filter and horizontal flow multi-soil-layering reactor（VFTF-HFMSL）.VFTF was equipped with a zeolite that has a large number of pores,which could benefit microbial growth and increase the contact areas with air.The mixed soil layering bioreactor in HFMSL included six soil mixture block layers surrounded by permeable layer in brick-like pattern.During the study,the hydraulic load was controlled at 660 L/m²/d,and the water inlet frequency was set to 1 second every 8 minutes.This study mainly used this device to find the effect of SDBS on the treatment of simulated wastewater.The device has a good removal effect on COD and SDBS was proved.As SDBS concentration was 750 mg/L,and COD concentration was 960 mg/L,the removal rate of COD was still 92.1%.NH₄⁺-N concentration was reduced from52.4 to 9.71 mg/L.SDBS has a great effect on the removal of nitrate,but after acclimation,effluent concentration could be maintained at 5.42 mg/L.Decomposition of SDBS in the system was mainly at top par t of VFTF.SDBS has the greatest impact on the microorganisms in middle or bottom of VFTF.Acetic acid made the microorganisms in VFTF use l ess carbohydrate,and this part of carbohydrate would enter HFMSL as denitrifying carbon source.The denitrification function in the system mainly depends on three parts,nitrification,denitrification and anammox.Anammox bacteria maintained high activity,while nitrifying bacteria were greatly inhibited by SDBS.The final effluent of total nitrogen concentration was mainly maintained by anammox bacteria.The concentration of nitrate effluent depends on the removal of VFTF.Under the influence of SDBS,the abundance of microorganisms that specifically decompose complex organic matter such as Firmicutes were richer,but the abundance of microorganism which specifically decomposed carbohydrate such as Nakamurella has not decreased.Microorganism that cannot specifically decompose complex organics would also oxidize SDBS by secreting some peroxides,such as hydrogen peroxid e,and would also produce a large number of enzymes.In 3D fluorescence,the peak at excitation/emission wavelength=310–340/370–430 nm was a characteristic peak of some active substances（such as some enzymes）in EPS.