Since the beginning of the industrial revolution atmospheric concentrations of carbon dioxide (CO_2), a major component of greenhouse gases, have increased significantly. There have been many attempts aimed at capturing, sequestrating, and reducing carbon dioxide emissions, but they have not been very efficient and economical. In this work the objective is to develop a sustainable system to reduce the carbon dioxide emissions of industries. Basically, in this method produced CO_2 from industries is injected in to a stream of wastewater and then is bioconverted to methane as a biogas. Methane will be produced based on the final step of anaerobic degradation in which methanogenic bacteria form methane from acetic acid or CO_2 and hydrogen. Consequently, after wastewater pollutant degradation (that provides acetic acid and hydrogen), methane with high efficiency could be produced with addition of carbon dioxide in a highly sustainable process. To investigate the feasibility of removing CO_2 by this method, a series of batch tests on pulp and paper wastewater were performed. In order to optimize the conditions, the effect of different conditions such as pH (6.5 to 7.5), temperature (20 to 35°C) on the efficiency of CO_2 and COD removal and methane production were investigated. The initial concentration of chemical oxygen demand (COD) was 1400 mg/L The results showed that COD levels decreased to the range of 345-680 mg/L which corresponds to a 24-50% conversion. Carbon dioxide removal was between 83- 1021 mg/L which corresponds to a 66-94% conversion. Both COD and CO_2 removal showed better efficiency at pH 6.5 and 35°C.
展开▼
