This chapter reviews the application of additives used in bioremediation of chlorinated solvents and fuels for groundwater and soil remediation. Soluble carbon substrates are applicable to most site conditions except aquifers with very high or very low groundwater flow. Slow-release and solid substrates are intended to be long-lasting in supplying carbon for microbial growth thereby minimizing operation and maintenance requirements. Microbes as special additives can be used to enhance bioremediation (bioaugmentation) where such microbes are lacking. Oxygen gas can be added to increase aerobic biodegradation, and nutrients addition may be needed to stimulate and maintain sufficient microbial population. pH modifiers to control acidity for optimal microbial growth and degradation can also be added. Delivery of additives to the subsurface can be accomplished through permanent injection wells, direct-push methods, or permeable reactive barriers (biowall). Potential issues with additive use include biofouling, stalling, short circuiting, displacement, reduced hydraulic conductivity, and secondary water quality deterioration. Methods and techniques to deal with these issues are provided and future research needs are identified.
Part of the book: Advances in Bioremediation of Wastewater and Polluted Soil
Anthropogenic activities, such as mining/smelting, result in the release and accumulation of heavy metal(loid)s in soil, posing serious human health and ecological risks. Due to the persistence of metal(loid)s, not undergoing any chemical and biological degradation, they can only be either immobilized or removed by, bioremediation and phytoremediation. Biochar is increasingly being recognized as a promising, effective material that can be used to remediate various contaminations including excessive heavy metals in soil. This chapter provides an overview of the state of the art on biochar resources, production processes and result of pyrolysis, surface characteristics of biochar, interactions of biochar with soil, and associated biota (microbes and plant). Furthermore, the understanding of characteristics of biochar and the interactions of biochar with soil and biota is necessary to assess the impacts of biochar on bioremediation and phytoremediation of heavy metal contaminated soil.
Part of the book: Advances in Bioremediation and Phytoremediation