Optimizing The Combined Bioelectrochemical With Sulfur Autotrophic Denitrification Process For Groundwater Nitrate Removal

Groundwater nitrate pollution due to extensive use of nitrogen fertilizer and impropertreatment of wastewater from the industrial sites. Biological denitrification have theadvantages which is more efficient to transformed nitrate into harmless material--nitrogen gas,the transform process doesn’t need organics, so biological denitrification is considered as themost prospect technology to treate groundwater. Sulfur autotrophic denitrification haveefficient to treat with nitrate, less cost and without harmful by-product. Sulfur autotrophicdenitrification process consumes alkalinity, and Bioelectrochemical autotrophic denitrificationprocess produce equivalent alkalinity, combined sulfur with bioelectrochemical autotrophicdenitrification will speed up denitrification process and balance system quality. This paperestablished both of single and double chamber Bioelectrochemical Autotrophic DenitrificationSystem(BADS), Sulfur Autotrophs Denitrification System(SADS), optimize the structure andoperating parameters. Combined Bioelectrochemical with Sulfur Autotrophic DenitrificationSystem(CBSAD) was set up for study on the effectiveness of denitrification, and optimize thecontrol conditions.The Sulfur Autotrophic Denitrification System(SADS) set up by this paper followedOne-order kinetics model. SADS suitable for deal with low sulfate groundwater, Theoptimum condition is the groundwater contains30mg/L nitrate, the best control conditionwasHRT=15min, the nitrogen volume-loading rates can up to3.04kg-N/m3d, there isalmost no nitrite accumulated.The Single-chamber Bioelectrochemical Autotrophic Denitrification System (SBADS)established by this paper can handle with groundwater of low nitrate concentration such as8mg/L, optimum conditions was HRT=3h, applied current was2mA, the nitrogenvolume-loading rates was0.051kg-N/m3d, and no nitrite be accumulated.The Double-chamber Bioelectrochemical Autotrophic Denitrification System (DBADS)combined porous sponge foam rubber can reduce oxygen evolution reaction. Add theheight-diameter ratio of reactor, a Large Ratio of Height to Diameter BioelectrochemicalAutotrophic Denitrification System (LRHDBADS) was built. The research show that DBADS can handling groundwater contain nitrate is15mg/L, the best control condition was HRT=3h, applied current was2mA, more than97.82%of nitrate was removed, the nitrogenvolume-loading rates up to0.125kg-N/m3d. The nitrogen volume-loading rates is twotimes as the System without porous sponge foam rubber. LRHDBADS suitable for treatmentraw water contains15mg/L nitrate, the best control condition was HRT=2h, applied currentis1mA, more than98%of nitrate was removed, the average the nitrogen volume-loadingrates was0.22kg-N/m3d, with0.1mg/L nitrite accumulated. Compare with usinggroundwater as original water, water scale doesn’t obvious in laboratory scale condition, themain components of the Water scale is CaCO3and MgCO3.Combined Bioelectrochemical autotrophic denitrification System with Sulfur autotrophsdenitrification System, A pilot scale CBSAD was built, and had preliminary debugging thereactor, The result was sulfur autotrophic denitrification system was biofilm culturing in15days. CBSAD has strong adjustment ability of pH value, it also reduce SO42-by-product.