Biomedical subjects

Zhou Deng

Publications and source records attributed to Zhou Deng.

5 recordsLinked to original sources

PubMed2006

Pilot-scale experiment on anaerobic bioreactor landfills in China.

Developing countries have begun to investigate bioreactor landfills for municipal solid waste management. This paper describes the impacts of leachate recirculation and recirculation loadings on waste stabilization, landfill gas (LFG) generation and leachate characteristics. Four simulated anaerobic columns, R1-R4, were each filled with about 30 tons of waste and recirculated weekly with 1.6, 0.8 and 0.2m(3) leachate and 0.1m(3) tap water. The results indicated that the chemical oxygen demand (COD) half-time of leachate from R1 was about 180 days, which was 8-14 weeks shorter than that of R2-R4. A large amount of LFG was first produced in R1, and its generation rate was positively correlated to the COD or volatile fatty acid concentrations of influent leachates after the 30th week. By the 50th week of recirculation, the waste in R1 was more stabilized, with 931.2 kg COD or 175.6 kg total organic carbon released and with the highest landfill gas production. However, this contributed mainly to washout by leachate, which also resulted in the reduction of LFG generation potential and accumulation of ammonia and/or phosphorus in the early stage. Therefore, the regimes of leachate recirculation should be adjusted to the phases of waste stabilization to enhance efficiency of energy recovery. Integrated with the strategy of in situ leachate management, extra pre-treatment or post-treatment methods to remove the nutrients are recommended.

Ammonia↗

PubMed2006

[Effects of leachate recirculation volume on its characteristic and landfill stabilization rate].

Impacts of recirculation volume on leachate characteristic and landfill stabilization rate were studied. Four simulated bioreactor landfill columns were operated weekly with different recirculation ratios, respectively 5.3%, 2.7%, 0.67% leachate and 0.33% water, in this comparative research. The results indicate that simulated reactor with 5.3% recirculation ratio has the most rapidly stabilization rate and release the most organic pollutant. The shortest methane generation delay was also observed in this column. While simulated reactor with 2.7% recirculation ratio formed the best microbe environment and kept the highest reactor temperature 35 degrees C. It also had the best impactive load capacity and treating efficiency to leachate, and removal of COD was 77% and BOD5 was 88% respectively. In actual projects, appropriate leachate recirculation volume should be chosen according to design purpose of landfill sites.

Bioreactors↗

PubMed2006

[Chemical stabilization technology in treating with flyash using apatite].

Toxicity leaching characteristics and chemical compositions of sample flyash collected from municipal solid waste incinerator was analyzed, it was clear that different heavy metals were contained in flyash and the heavy metal leaching concentration for Pb, Zn, Cd was 11.8, 164.9 and 31.2 mg/L respectively which was much higher than that in Hazardous Waste Toxicity Leaching Standards. A new kind of inorganic chemical agent apatite was chosen to treat with this kind of incineration flyash, the results indicate that the heavy metals (not including Cd in some samples) in the treated flyash using apatite at dosage 7% can reach the landfilling standards for hazardous waste, and the treated flyash can have better stabilization when the size of apatite was 74 microm, and the heavy metal leaching concentration of the treated flyash keep stable at a curing time of 1 day, and it can keep stabilization with a broader pH value of 3 to 11. Thus the risk of secondary pollution for the treated flyash was reduced dramatically when the environment conditions change.

Apatites↗

PubMed2006

[Pilot scale research on impacts of leachate recirculation on its ultimate treatment].

Two pilot scale simulated columns, with and without leachate recirculation, were erected to study impacts of leachate recirculation of traditional anaerobic bioreactor landfill on leachate ultimate treatment methods. The results indicate that recirculation can remove organic pollutants visibly, but it isn't effective to inbiodegradable components, nitrogen (N) and phosphorus (P) pollutants. After recircualted for 44 weeks, test column has a BODs removal ratio of 98.5%. BOD5/COD value of outflow is only 0.07. BOD5/TN and BOD5/TP are 0.13 and 11 respectively, which are much lower than the adequate value for anaerobic microorganisms. It's difficult to treat this kind of leachate by traditional biological methods. When a bioreactor landfill is being designed, leachate characteristics after recirculated should be well considered and adequate leachate treatment, landfill and recirculation schemes should be chosen to take full advantage of waste stack decontamination effects.

Anaerobiosis↗

PubMed2005

[Heavy metal stabilization in municipal solid waste incineration fly ash using soluble phosphate].

The physico-chemical characteristics of municipal solid waste incineration fly ashes was analyzed. It indicated that the main elements of fly ashes are Ca, Cl, K, S and Si, and many heavy metals such as Pb, Zn, Cu, Mn and Cr can be found in fly ashes, and the heavy metal leaching toxicity such as Pb, Cu, Zn and Cd is much higher than the standards. A new kind of stabilization agent-soluble phosphate is chosen to treat with fly ash, different influence factors including agent dosage, curing time and pH are taken into consideration to test its stabilization for the stabilized fly ash. The experimental results indicate that fly ash treated with soluble phosphate can have excellent stabilization effect, and the leaching toxicity for Pb, Cd and Zn can be reduced by 97.5%, 91.6% and 95.5% at a phosphate dosage of 3%; curing time can not influence its stabilization; and, stabilized fly ash using soluble phosphate can keep long-term stabilization at a broad pH value.

Carbon↗