Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned...Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned to soil,thereby seriously undermining biochar＇s efficacy. Therefore, the transformation mechanisms of biochar p H,mass, nutrients and metals during pyrolysis under different atmospheres and temperatures were studied such that the best method for biochar preparation could be developed. Several conclusions can be reached：（1） a CO2 atmosphere is better than a N2 atmosphere for biochar preparation, although preparation in a CO2 atmosphere is not a common practice for biochar producers;（2） 350 ℃is the best temperature for biochar preparation because the amount of nutrient loss is notably low based on the premise of straw transferred into biochar; and（3） transforming mechanisms of pH, N, P and K are also involved in the biochar preparation process.展开更多
Bauxite residue is a highly alkaline material generated from the production of alumina in which bauxite is dissolved in caustic soda.Approximately 4.4 billion tons of bauxite residues are either stockpiled or landfill...Bauxite residue is a highly alkaline material generated from the production of alumina in which bauxite is dissolved in caustic soda.Approximately 4.4 billion tons of bauxite residues are either stockpiled or landfilled,creating environmental risks either from the generation of dust or migration of filtrates.High alkalinity is the critical factor restricting complete utilization of bauxite residues,whilst the application of alkaline regulation agents is costly and difficult to apply widely.For now,current industrial wastes,such as waste acid,ammonia nitrogen wastewater,waste gypsum and biomass,have become major problems restricting the development of the social economy.Regulation of bauxite residues alkalinity by industrial waste was proposed to achieve‘waste control by waste’with good economic and ecological benefits.This review will focus on the origin and transformation of alkalinity in bauxite residues using typical industrial waste.It will propose key research directions with an emphasis on alkaline regulation by industrial waste,whilst also providing a scientific reference point for their potential use as amendments to enhance soil formation and establish vegetation on bauxite residue disposal areas(BRDAs)following large-scale disposal.展开更多
Bauxite residue is a highly alkaline waste product from refining bauxite ore.Bioremediation driven by microbial activities has been evidently effective in lowering the alkalinity of bauxite residues,which is critical ...Bauxite residue is a highly alkaline waste product from refining bauxite ore.Bioremediation driven by microbial activities has been evidently effective in lowering the alkalinity of bauxite residues,which is critical to the initiation of pedogenesis under engineered conditions.The present study investigated the changes of alkalinity and aggregation of bauxite residue at different depth in response to the colonization of Penicillium oxalicum in columns.The results demonstrated that the inoculation of P.oxalicum decreased the residue’s pH to about 7 after 30 d only at the surface layer,which was exposed to aerobic conditions.The formation of aggregates was improved overall in the organic matter treated bauxite residue.However,the EC of bauxite residue increased with time under the incubation condition,probably due to accelerated hydrolysis of sodium-rich minerals.The inoculation of P.oxalicum had no effects on urease activity,but increased cellulose enzyme activity at surface layer only.展开更多
基金Supported by the National Natural Science Foundation of China(No.41571283)
文摘Returning biochar to soil is a heavily researched topic because biochar functions well for soil improvement. There is a significant loss of nutrients, which occurs during biochar preparation before biochar is returned to soil,thereby seriously undermining biochar＇s efficacy. Therefore, the transformation mechanisms of biochar p H,mass, nutrients and metals during pyrolysis under different atmospheres and temperatures were studied such that the best method for biochar preparation could be developed. Several conclusions can be reached：（1） a CO2 atmosphere is better than a N2 atmosphere for biochar preparation, although preparation in a CO2 atmosphere is not a common practice for biochar producers;（2） 350 ℃is the best temperature for biochar preparation because the amount of nutrient loss is notably low based on the premise of straw transferred into biochar; and（3） transforming mechanisms of pH, N, P and K are also involved in the biochar preparation process.
基金Projects(41877551,41842020)supported by the National Natural Science Foundation of ChinaProject(201509048)supported by the Environmental Protection’s Special Scientific Research for Chinese Public Welfare Industry
文摘Bauxite residue is a highly alkaline material generated from the production of alumina in which bauxite is dissolved in caustic soda.Approximately 4.4 billion tons of bauxite residues are either stockpiled or landfilled,creating environmental risks either from the generation of dust or migration of filtrates.High alkalinity is the critical factor restricting complete utilization of bauxite residues,whilst the application of alkaline regulation agents is costly and difficult to apply widely.For now,current industrial wastes,such as waste acid,ammonia nitrogen wastewater,waste gypsum and biomass,have become major problems restricting the development of the social economy.Regulation of bauxite residues alkalinity by industrial waste was proposed to achieve‘waste control by waste’with good economic and ecological benefits.This review will focus on the origin and transformation of alkalinity in bauxite residues using typical industrial waste.It will propose key research directions with an emphasis on alkaline regulation by industrial waste,whilst also providing a scientific reference point for their potential use as amendments to enhance soil formation and establish vegetation on bauxite residue disposal areas(BRDAs)following large-scale disposal.
基金Projects(41877511,41842020)supported by the National Natural Science Foundation of ChinaProject(2018zzts421)supported by the Innovative Project of Independent Exploration of Central South University,China
文摘Bauxite residue is a highly alkaline waste product from refining bauxite ore.Bioremediation driven by microbial activities has been evidently effective in lowering the alkalinity of bauxite residues,which is critical to the initiation of pedogenesis under engineered conditions.The present study investigated the changes of alkalinity and aggregation of bauxite residue at different depth in response to the colonization of Penicillium oxalicum in columns.The results demonstrated that the inoculation of P.oxalicum decreased the residue’s pH to about 7 after 30 d only at the surface layer,which was exposed to aerobic conditions.The formation of aggregates was improved overall in the organic matter treated bauxite residue.However,the EC of bauxite residue increased with time under the incubation condition,probably due to accelerated hydrolysis of sodium-rich minerals.The inoculation of P.oxalicum had no effects on urease activity,but increased cellulose enzyme activity at surface layer only.
