Pretreatment of Biogas Slurry by Modified Biochars to Promote High-Value Treatment of Wastewater by Microalgae

Zhiqiang Gu, Qi Zhang, Guobi Sun, Jiaxin Lu (), Yuxin Liu, Zhenxia Huang, Shuming Xu, Jianghua Xiong and Yuhuan Liu ()
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Zhiqiang Gu: State Key Laboratory of Food Science and Technology, Engineering Research Center for Biomass Conversion, Nanchang University, Ministry of Education, Nanchang 330047, China
Qi Zhang: State Key Laboratory of Food Science and Technology, Engineering Research Center for Biomass Conversion, Nanchang University, Ministry of Education, Nanchang 330047, China
Guobi Sun: State Key Laboratory of Food Science and Technology, Engineering Research Center for Biomass Conversion, Nanchang University, Ministry of Education, Nanchang 330047, China
Jiaxin Lu: Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry, Beijing Technology and Business University, Beijing 100048, China
Yuxin Liu: Jiangxi Rural Energy and Environment Agency, Nanchang 330000, China
Zhenxia Huang: Jiangxi Rural Energy and Environment Agency, Nanchang 330000, China
Shuming Xu: Dingnan Agricultural and Rural Bureau, Ganzhou 341900, China
Jianghua Xiong: Agricultural Ecology and Resources Protection Station of Jiangxi Province, Nanchang 330046, China
Yuhuan Liu: State Key Laboratory of Food Science and Technology, Engineering Research Center for Biomass Conversion, Nanchang University, Ministry of Education, Nanchang 330047, China

Sustainability, 2023, vol. 15, issue 4, 1-15

Abstract: High concentrations of contaminants such as ammonia nitrogen and organic matter in full-strength wastewater severely inhibit the growth of microalgae, contributing to lower biomass accumulation and contaminant removal efficiency. To overcome this limitation, modified biochars prepared from pine sawdust and sugarcane bagasse were used in this study as an adsorbent–desorbent for the pretreatment of wastewater to promote the growth of microalgae. The results showed that the two modification methods (acid/alkaline modification and magnesium salt modification) used in the experiment could increase the abundance of oxygen-containing functional groups. Moreover, magnesium salt modification could effectively improve the pore structure of biochar surfaces and increase the specific surface areas. Compared with the pristine biochars, the adsorption performance of the modified biochar was found to be significantly higher for nutrients in wastewater. The adsorption capacity of the acid/alkaline-modified pine sawdust biochar reached 8.5 and 16.49 mg∙g −1 for ammonia nitrogen and total organic carbon in wastewater, respectively. The magnesium salt modified pine sawdust biochar achieved a more comprehensive nutrients adsorption capacity of 15.68, 14.39, and 3.68 mg∙L −1 for ammonia nitrogen, total organic carbon, and total phosphorus, respectively. The mechanism of ammonia nitrogen adsorption was mainly the complexation of surface -OH functional groups, while the adsorption mechanism for phosphate was mainly the complexation of -OH and Mg-O functional groups and the chemical precipitation of MgO or Mg(OH) 2 attached to the surface.

Keywords: biochar; biogas slurry; wastewater pretreatment; modification; nutrients removal (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2023
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