Organics In Gas-field Wastewater And It’s Treatment By Heterogeneous Fenton Method

The overall index, such as chemical oxygen demand(COD), biochemical oxygen demand(BOD5) and total organic carbon(TOC), is commonly used as a measure of organics in wastewater. These measures, however cannot reflect the categories of organics(chemical oxygen consumption or biologic oxygen consumption) in varied gas field wastewater and thus is not very helpful to subsequent selection of processing technology and improving treatment effect. According to the current available literatures, there is less people concerned the detailed analysis of organics in gas field wastewater, especially in China.In this work, conventional water quality analysis were firstly carried out and the results showed that COD, oil, suspended solids,turbidity, sulfide and chloride were all at a high concentration level. A BOD5/COD ratio of 0.11 showed this gas field wastewater was resistant-biodegradable. Further analysis indicate the vast majority of organics in the wastewater was Alkanes, cycloalkanes and aromatic hydrocarbons, as well as a small amount of alcohols and ketones.According to these analysis results, a heterogeneous Fenton process based on iron-pillared-bentonite catalyst was designed for treating the organics in this wastewater. The focuses of this part of work was mainly on preparation of the catalyst and its performance in treatment of organics in selected gas field wastewater. Several preparation routes were compared and finally a microwave based method was adopted, with a Fe/soil ratio of 4mmol/g solid-liquid ratio of 1:20; water bath temperature of 40℃, nFe: nNa of 1:1.5 and a power of 539 w.Considering the CODcr removal rate and the cost, parameters of present heterogeneous Fenton process for treatment of organic matter in 100 ml selected waste waters were: pH ≈7, H2O2 dosing quantity of 1.0 ml, additive quantity of iron pillared bentonite is 1 g, reaction for 2 h at room temperature. Further experiments showed that enough sunlight could promote the heterogeneous Fenton reaction to remove the organic matter in waste water. The CODcr removal rate using the as-prepared catalyst can still reach more than 60% after 5 recycling.Qualitative analysis of organics after the processing showed that treatment could significantly reduce the categories and concentration of organic matter in the wastewater. Specifically, alkanes almost degraded completely, but benzenes in the original wastewater almost remained in the processed water, and alcohols and ketones maybe slightly degraded under prescient conditions.