Journal
JOURNAL OF ENVIRONMENTAL MANAGEMENT
Volume 226, Issue -, Pages 241-248Publisher
ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jenvman.2018.08.048
Keywords
Biogas; Carbon adsorption; Spent wash; Wet air oxidation
Categories
Funding
- Rajiv Gandhi Science and Technology Commission (RGSTC), Government of Maharashtra, India [RGSTC/File 2013/DPP-111/CR-26]
Ask authors/readers for more resources
In the present work, catalytic wet air oxidation (WAO) technique was applied to biomethanated spent wash from a local sugar factory. This wash water exhibited high biological oxygen demand (BOD5 = 8100 mg/L) and chemical oxygen demand (COD = 40,000 mg/L). The objectives of oxidative pre-treatment were two-fold, viz. efficient treatment of wash water and enhanced biogas recovery. For the catalytic oxidation process, two iron-based heterogeneous catalysts were employed, viz. Fe2O3 and Fe/C. To synthesize the Fe/C catalyst, activated carbon (AC) support was modified either by thermal treatment or chemical treatment with nitric acid; accordingly, the catalyst was named as Fe/AC-T or Fe/AC-N. In a batch slurry reactor, catalyst performance was investigated at T = 175 degrees C, P-O2 = 0.69 MPa and omega = 33 mg/L (here, T, P-O2 and omega denote temperature, oxygen partial pressure and catalyst loading) for 1 h. Based on the conversions of COD and total organic carbon (TOC) and the improvement in biodegradability index (BI), it was found that the activity of the catalysts reduced in the order: Fe/AC-N > Fe/AC-T > Fe2O3. The results were more encouraging (COD conversion = 87%, color reduction = 88% and BI value = 0.71) when carbon adsorption (5% w/v) followed WAO over Fe/AC-N. Clearly, our novel hybrid process for pre-treatment, viz. wet oxidation-carbon adsorption showed potential. Post bio-methanation, around 1.2 Nm(3) biogas (CH4 72%) was formed per cubic meter of the wastewater; without pre-treatment by catalytic WAO and carbon adsorption, the yield of biogas (CH4 11%) was just 1 Nm(3) for every cubic meter of wastewater. After a last aerobic treatment step, 97% COD was removed and BI value was 0.84. Finally, a kinetic model was proposed to describe kinetics of COD reduction. In this way, a promising method was suggested for treating a complex wastewater.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available