Four kinds of slow-release carbon source composite materials were prepared and used as carbon source and biofilm attachment carrier for groundwater nitrate pollution bioremediation. Their performances were detected through static and continuous experiments. The results showed that: In the static experiments, HB20 and HB40 had general release carbon ability, their CODMn were 5.42 and 12.83 mg/L respectively; In the continuous experiments, NO3-N removal rate of HLE decreased from 57.9% to 13.1% within 30 days, the denitrification endurance was not good. Organic carbon source can be released continuously by HBE which had the best denitrifying effect. In the operation of 66 days, above 96.0% NO3-N was removed and NO2-N level was below 0.02mg/L when influent NO3-N =30.0mg/L and HRT=24h. HBE was the most suitable carbon source carrier material which was used in groundwater nitrate pollution bioremediation.
Many nitrate pollution cases exceed the threshold as recommended by the World Health Organization (50 mg NO3/L) and by the USA (10 mg N/L) for drinking water. In-situ denitrification was regarded as a good method to decrease nitrate contamination but is restricted by carbon absent in groundwater. Considering the disadvantages of known carbon sources, this paper provided slow-release organic carbon-source (SOC) technique to solve the problem and the results showed that SOC materials showed good performance during simulated groundwater denitrification. Structure analysis suggested that hydroxy chemical bond existed between PVA and starch in SOC and surface configuration changed with materials dissolving into water. After seven days of domestication, with 40–50 mg/L initial NO3-N, denitrification efficiency increased from 80.6% to 90.7% and the real COD consumption per N-NO3 reduction was 1.82–3.73 with 2.79 as average. Denitrification process followed the law of zero order kinetics and the parameter of denitrification dynamics, K, was from 0.1366 to 0.1873. It was suggested that SOC was a potential carbon source material (electron donor) suitable for in-situ groundwater denitrification.
The Selection of Natural Solid-phase Slow-release Organic Carbon-source Materials for the Denitrification Permeable Reactive Barriers (PRB)