[Performance of slow-release organic carbon-source (SOC) materials for in-situ biological denitrification in groundwater].

ABSTRACT

As lack of electron donor (carbon source) is a key problem of in-situ denitrification in groundwater, slow-release organic carbon-source (SOC) materials were produced as appropriate electron donor in denitrification PRB. GPVAS and GEPVAS series were manufactured by blending starch and PVA together, with alpha-amylase as the additive, and their performance was detected through SEM and static batch experiments. The results showed that PVA formed the framework filling with starch molecule, and the carbon releasing process followed the law of second order kinetics. Equilibrium concentration of COD (c(m)) and release rate coefficient (k) were key factors of kinetics evaluation. Both c(m) and k of GPVAS-40 were the lowest. The influence of alpha-amylase to the performance of SOC materials was remarkable. The c(m) values would ascend rapidly with augmenting of alpha-amylase content, while the releasing speed rose when amylase activity was lower than 0.03 U/g and then decreased. Consequently, the releasing process was controllable through changing the content of starch and activity of alpha-amylase to meet needs of different situations and pollution of groundwater and improve the effect of in-situ nitrate removal.