Advanced Materials Research Vol. 878

Abstract: Resource technology for food waste has become the research hot recently. To perform ethanol fermentation from food waste could realize energy recovery and pollution prevention. This study investigated the effects of two kinds of immobilization carriers, loofa sponge and fiber ball on ethanol fermentation from food waste. The seven runs of fermentation experiments demonstrated that the fermentation broth with fiber ball showed an increase of residue sugar concentration (31.98g/l) and a decrease of sugar utilization ratio (60.02%) in the fourth run. When it came to the seventh run of experiment, the sugar utilization ratio was only 49.04%, which showed that the fermentation yield by the yeast decreased significantly. While the fermentation by loofa sponge revealed stable fermentation efficiency, the sugar utilization ratio were all above 80%. The effect of size and inoculum for loofa sponge showed that 3 gram dry loofa sponge in 100 ml saccharification liquid was suitable. While the size had little effect on the fermentation.

Abstract: The Gannan region is the largest navel orange planting area in the world and has the largest production in China. However, about 5 million tons of navel orange waste (NOW) produced annually. NOW has a great environmental risk because of its high content of organic matter and moisture. Anaerobic digestion of NOW with high nitrogen content waste is a promising alternative to treat these wastes. The effect of swine manure (SM), waste active sludge (WAS) as co-substrates and different mixing ratio were examined in three batch-scale studies. In the first investigation, co-digestion of NOW with SM resulted low methane yield and high concentration of VFAs. In the second investigation, NOW was co-digested with WAS, the methane yield was improved by 260% when the mixing ratio of NOW to WAS (VS/VS) was shifted from 1:2 to 2:1. In the third investigation, the co-digestion of NOW with SM and WAS was conducted. Co-digestion of three substrates has higher methane yield than that of previous two studies, with the exception of equal amounts of NOW with co-substrates (mixing ratio of NOW to SM to WAS was 2:1:1). The highest methane yield of all experiments was 0.20 m³ kg^-1VS added while the mixing ratio of NOW to SM to WAS was 1:2:1. It seemed to obtain stable digestion performance, the mixing ratio of co-substates to NOW should not be lower than 1:1. WAS was a better co-substrate than SM, as WAS was capable to supply more organic nitrogen to create positive synergistic effects.

Abstract: A large number of Chinese herbs residues were produced during the production of honeysuckle and midday tea. Usually, the content of organic components in the residues was at a high level. These residues would pose a great threat to the local water environment, if they were not treated and disposed properly. In this paper, a self-prepared anaerobic reactor was utilized to treat the residues of honeysuckle and midday tea in semi-solid phase media. The anaerobic sludge was inoculated into the residues for anaerobic digestion at the temperature of 37±1°C, and ISRs (ISRs is the total solid mass ratio between inoculum and substrate) were 1:2, 1:1, 2:1 respectively. The result showed that the ultimate maximum yield of methane was the under ISRs of 1:1, the cumulative methane production volume of honeysuckle and midday tea dregs were 5832mL/100g and 5591mL/100g, respectively, after 192h digestion. Under the best inoculation ratio of 1:1, another mesophilic anaerobic experiment was carried out by mixing the residues of honeysuckle and midday tea as substrate at different ratios of 0:3, 1:2, 1:1, 2:1 and 3:0, respectively, which were to compare the methane production at 37±1°C. The result indicated that the ultimate maximum yield of methane was under mixed ratio of 1:2, the cumulative methane production volume of the mixed Chinese herbs residues was 9110 mL/100g after 192h digestion. Furthermore, the zero-order kinetic model was found to be suitable to characterize the removal ratio of substrate during 0~108h digestion while the biogas was generated fast, and the kinetic constant k was 50.49mL/h. To obtain the ultimate maximum rate of methane production, the anaerobic reaction should be controlled under the stage of zero-order reaction. Thus, the experimental results could provide scientific proof for anaerobic treatment and methane recycling in organic waste of Chinese herbs enterprises.

Abstract: The performances of leaching-upflow blanket filter (UBF) anaerobic digestion for biogas production of kitchen waste was investigated. To find out the process parameter variations of acidification phase and the methane production performance of methanogenic phase, kitchen waste from division of environment sanitation management of Changzhou was used as feedstock. The results show that the ammonia in anaerobic system cumulated continuously throughout the digestion; pH value maintained at7.6; At first the value of COD ranged from 20000 mg/L to 140000 mg/L to the final UBF water 10000mg/L to 12000 mg/L; Volatile fatty acid (VFA) reduced to 150mg/L with the increase of the days; total nitrogen increases first and then decreases, finally, it keeps at 1600 mg/L; The concentration of alkalinity increased slightly; biogas production is stable, The rate of gas generation is above0.30 m3/kgCOD . These results provide a proof of the feasibility for kitchen waste anaerobic methane fermentation.

Abstract: This paper investigated the influence of the inoculation volume of dewatering sludge on thermophilic anaerobic digestion in residue of fermentative hydrogen production using combined sludge and food waste in batch experimental systems. The inoculum to residue ratios were 10%, 30%, 50%, 70%, 90%, respectively. The results showed that the biogas production increased with the inoculation volume except for 90%,and the optimum inoculation volume was 70%.

Abstract: Municipal solid waste is a big problem in China. Separating and collecting recyclables from municipal solid wastes is a key approach for resolving waste problems and promoting circular economy. The current collection and recycling of recyclables from municipal solid waste is reviewed for better perspective. The material and value stream are summarized for understanding the potential direction of waste and recyclables. The stakeholder for recyclables collection and recycling is identified and their roles are analyzed. Situation of recycling enterprises is introduced. Finally, some comments for promoting recycling industry development are made for reference.

Abstract: Previous studies usually used regression analysis on OLS model to determine the influencing factors of MSW clearance volume, but OLS model did not take into account the spatial dependency of the dependent variable. In this study, firstly, as the dependent variable, the spatial autocorrelation of MSW clearance volume is tested to explore its spatial effect, and spatial regression model is introduced to establish a MSW-SEM (spatial error model) model. Secondly, variance inflation factor and partial correlation coefficient are used to remove the multicollinearity of 33 potential factors. Then using MSW-OLS model and MSW-SEM model respectively analyzes the influencing factors of MSW clearance volume in China mainland. Finally, comparative analysis of above two models results is taken by Akaike Information Criterion, determination coefficient, significance of parameter estimation, and spatial dependence of residuals. Result shows that community health center visits, accommodation enterprises main business profit, passenger capacity, investment enterprises profit rate of Hong Kong/Macao/Taiwan/overseas and urban road lighting were dominant influencing factors of MSW clearance volume. Although MSW-OLS and MSW-SEM models have similar regression coefficients, MSW-SEM model shows better model fitting because of its lower AIC, higher R2, and smaller global Morans I value. In summary, compared with MSW-OLS model, MSW-SEM model is more successful in identifying the dominant factors of MSW clearance volume due to its consideration of spatial dependency.

Abstract: Utilize of property evaluation method for an immobilizing procedure is very important. In this paper, an immobilizing procedure was used to stabilize heavy metals in tested soils. Tessier sequence extract procedure (SEP), toxicity leaching procedure (TCLP) and simple bioaccessibility extraction test (SBET) were used to evaluate the efficiency of the stabilization procedure. The leachability, bioaccessibility and speciation of As, Cu and Pb in the tested soils were analyzed using Tessier SEP, TCLP and SBET method separately. The results indicated that the most active part of the heavy metals could be extracted out by TCLP method and it could be used to evaluate the risk of the tested soils. Tessier method divided heavy metals in soils to different fractions. Monitoring the changes of different fractions during the immobilizing procedure could help fully understand the mechanism of stabilization. The SBET method simulated the human digest system and evaluated the risk changes to human during the immobilizing procedure. And it helped to reveal the potential risk of chemical stability. In our project, these three evaluation method should be utilized properly to help accessing the risk, electing suitable immobilizing method and evaluating the efficiency of stabilization.

Abstract: Medical waste is a special category of waste with potential health and environment risks. Medical waste management and disposal is a difficult problem in the western China because the shortage of financial support. Kunming city was selected to assess the current achievement and experience of medical waste management and disposal. Kunming municipal government solved the problem of medical waste disposal by adopting the model of BOT (Build-Operate-Transfer). The analyzed results showed that there was a good achievement of medical waste disposal in Kunming city that medical waste disposal realized centralized and normalized disposal, and centralized disposal had amounted to one hundred percent in urban area since 2006. Medical waste disposal in Kunming city mainly includes three steps, that is,the sort and collection of respective medical institutions, the centralized collection and transport of Kunming Center for Medical Waste Centralized Disposal (KCMWCD) and incineration . Kunming municipal government approved franchise for Medical waste disposal. The government has strengthened the medical waste disposal by building the effective administrative monitoring system of medical waste, organizing some meetings and visiting the place of medical waste disposal for relevant person and training them, and imposing the medical waste disposal fee on medical institution.

Abstract: A new kind of gypsum retarder was prepared from waste penicillin mycelium (WPM), a harmful solid waste from pharmaceutical factory. The results indicated that the optimum treatment conditions were pH value 11, temperature 80 °C and treatment time 1.5 h. Compared with sodium citrate and sodium polyphosphate, WPM retarder can effectively prolong the setting time of gypsum with less influence on mechanical strength. The crystal morphology microstructure of gypsum containing retarder was studied with SEM and the reason why the mechanical strength loss of gypsum were also explained in this paper.