Bioreactor performance using biochar and its effect on aerobic granulation.

Area of Science:

• Environmental Science
• Environmental Engineering
• Biotechnology

Background:

• Petroleum wastewater poses significant environmental challenges due to its complex organic pollutants.
• Aerobic granular sludge (AGS) technology is a promising method for wastewater treatment, but its efficiency and stability can be improved.
• Biochar, a carbon-rich material derived from biomass pyrolysis, has shown potential in enhancing biological wastewater treatment processes.

Purpose of the Study:

• To investigate the impact of different biochars (rice husk, rice bran, walnut shell) on aerobic granulation and the performance of reactors treating petroleum wastewater.
• To evaluate how biochar addition affects key wastewater treatment parameters such as COD and TN removal, granulation time, and resistance to shock loading.
• To understand the role of biochar's physicochemical properties in influencing AGS system performance.

Main Methods:

• Three types of biochar (rice husk biochar, rice bran biochar, walnut shell biochar) were added to reactors treating petroleum wastewater.
• Aerobic granulation process, chemical oxygen demand (COD) and total nitrogen (TN) removal efficiencies, and reactor stability under shock loading conditions were monitored.
• Microbial community analysis was performed to identify bacteria enriched in the granular sludge containing biochar.

Main Results:

• All tested biochars significantly reduced aerobic granulation time by approximately 15 days compared to the control.
• Average COD and TN removal efficiencies increased by 3.2%-5.1% and 10%-13%, respectively, with biochar addition.
• Biochar addition enhanced the resistance of the AGS system to shock loading, with rice bran biochar resulting in the most stable reactor and rice husk biochar yielding the largest initial granule size.

Conclusions:

• Biochar derived from agricultural waste (rice husk, rice bran) and walnut shells effectively promotes aerobic granulation and improves the treatment of petroleum wastewater.
• The incorporation of biochar enriches specific bacterial communities crucial for petroleum pollutant degradation, leading to enhanced nutrient removal and system stability.
• The findings highlight the potential of utilizing biochar as a cost-effective additive to optimize AGS systems for treating challenging industrial wastewaters.