Enhance nitrogen removal in bioretention cells with addition of hydrothermal pre-treated pine barks as external carbon source

The problem of poor carbon source is a common factor limiting the nutrients removal in bioretention cells (BRCs). This study aimed to investigate the feasibility of using modified biomass in BRCs filled with a mixture of fly ash ceramsite and pumice fillers to enhance nitrogen removal. Different pretreatment methods (hydrothermal-treated, acid-treated and alkali-treated) were attempted, and hydrothermal pretreatment showed a best performance in carbon release ability. The scanning electron microscopy showed that the lignin in hydrothermal pretreated pine barks (H-PBs) was destroyed, and the fiber structure became thinner with more irregular folds, which improved the accessibility of cellulose and attachment of microorganisms. The addition of H-PBs significantly enhanced the nutrients removal in BRCs, and the removal rates of TN and NO3−-N increased by 23.25% and 38.22% compared with those in BRC-A (without external carbon source), but the removal rate of NH4+-N was inferior to BRC-A. Besides, the large carbon release amount of H-PBs did not deteriorate the effluent quality, with COD removal rate of 87.98% in the 48 d. These results indicate that the BRCs by adding H-PBs could intensify the denitrification process.

Adjusting SiO2 : C mole ratios in rice hull ash (RHA) to control carbothermal reduction to nanostructured SiC, Si3N4 or Si2N2O composites

SiO2 : C mole ratios in RHA are controlled using an unconventional method, by which nanocomposites are synthesized via carbothermal reduction exploiting the intrinsic nanoscale SiO2 and carbon with no need for adding an external carbon source.

Advanced treatment of coal chemical reverse osmosis concentrate with three-stage MABR

A MABR system was constructed to treat coal chemical reverse osmosis concentrate without an external carbon source.

Roles of extracellular polymeric substances in uranium immobilization by anaerobic sludge

The specific roles of extracellular polymeric substances (EPS) and how factors influenced EPS’s roles during U(VI) immobilization are still unclear. In this study, high content of U with the main form of nanoparticles was detected in EPS, accounting for 10–42% of total U(VI) removal. EPS might be utilized as energy source or even as electron donors when external carbon source was unavailable. The influencing degree of each experimental parameter to uranium (U) removal process was elucidated. The influential priority to U(IV)/U(VI) ratios in sludge was as follows: acetate, U(VI), and nitrate. The influential priority to total EPS contents was as follows: U(VI), nitrate and acetate. The complex interaction mechanism between U(VI) and EPS in the U immobilization process was proposed, which might involve three ways including biosorption, bioreduction and bioprecipitation. These results indicate important and various roles of EPS in U(VI) immobilization.

Complete Treatment of Food Waste using Vertical Carbonizer

Conventional food processor was used as compost or feed after solid-liquid separation by crushing and compression. However, feedstuffs became difficult due to the inability to prevent toxic substances, and composting was reluctant to use inappropriately and excessively salty. Therefore, using food waste as its own heat source in the drying process will reduce fuel costs and provide new food treatment methods. The food waste that is rich in fat and protein is distilled and dried, the solid material is used as livestock feed, and the condensate is completely recycled as an external carbon source of deodorant or sewage treatment plant. At this time, the excess solid component is pyrolyzed in a vertical type carburetor, and a combustible gas is produced and burned to be utilized as a heat source of the food drying apparatus. The pyrolysis temperature of the dried food waste for making flammable gas was maintained at 400 ° C and in this case, the harmful gas was below the environmental standard. By maintaining 1200 ° C during combustion, the risk of dioxin was eliminated. The vertical carbonization system can be used as a solid fuel additive, a black gray concrete additive, a soil additive and the like, while the hydrocarbon gas produced by pyrolyzing the solid structure effectively is used as a clean fuel to reduce the fuel cost. Condensate is used as an external carbon source for liquid fertilizers, deodorizers and sewage treatment. This device is not necessary when using incinerator waste heat. In a food waste disposal facility in an area without an incinerator, the fuel can be self-sufficient and effectively reduce fuel costs.