Improvement of Oxygen Release from Calcium Peroxide-polyvinyl Alcohol Beads by Adding Low-cost Bamboo Biochar and Its Application in Bioremediation

A limited concentration of dissolved oxygen commonly reduces the effectiveness of groundwater bioremediation. A novel bamboo biochar oxygen-releasing bead (ORB) was prepared and its application in groundwater bioremediation was evaluated. The results reveal that bamboo biochar effectively adsorbed benzene, toluene, ethylene, and xylene. The Freundlich model described the adsorption behavior (R2=0.990) well. The response surface method was used to prepare biochar-ORBs. Results indicate that the proportions of calcium peroxide, citrate, polyvinyl alcohol, and bamboo biochar for the optimal oxygen-releasing capacity of biochar-ORBs were 20:2.22:9.23:31.5 (w/w/w/w). A multiple linear regression equation effectively predicted oxygen releasing capacity (R2=0.991). A column experiment indicated that the period of oxygen release from biochar-ORBs (104 days) was much longer than that from ORBs (51 days). The mechanical strength of biochar-ORBs (disintegration ratio: 3.4%) exceeded that of ORBs (disintegration ratio: 6.9%). Degraders that contained biochar-ORBs rapidly removed 99% toluene at a concentration of 45.6mgL-1. Scanning electron microscopy showed that degraders attached to and grew on biochar-ORBs following bioremediation. Taken together, the results reveal that biochar-ORB is a potential oxygen-releasing material for use in groundwater bioremediation. A limited concentration of dissolved oxygen commonly reduces the effectiveness of groundwater bioremediation and oxygen-releasing bead (ORB) can be used to provide oxygen for groundwater. A low-cost, novel biochar-ORB was prepared in this study. It has long oxygen releasing period (104 days) and is suitable for using in groundwater bioremediation.