To obtain information that can be used as reference for improving the environment inside and surrounding the open channels receiving johkasou effluent, the formation and correlation of sediment bed bacterial density with water quality were evaluated with multivariate statistical analysis based on measured data for water and sediment samples collected for 8 times from 6 sites of an open channel that receives johkasou effluent in a residential area of Gifu Prefecture, Japan. Statistical analysis included principal component and factor analysis (PCA/FA), cluster analysis (CA) and correlation analysis. The PCA/FA results showed that 3 dominant factors were responsible for the water quality data structure, accounting for 85.12% of the total variance in the dataset. Hierarchical cluster analysis grouped 6 study sites into 3 statistically significant clusters, reflecting different characteristics and pollution levels of the sites. Correlation analysis revealed statistically significant relationships of the sediment bed bacterial density with BOD, total nitrogen and total phosphorus in the water of the channel receiving johkasou effluent.
Application of membrane filtration processes in large-scale water treatment facilities has expanded in recent years. In particular, they are increasingly used for surface water treatment (river and lake waters) rather than for groundwater treatment. Generally, coagulation is used to remove colloidal and suspended particles in surface water, but the effects of coagulation, which is a pre-treatment process in membrane filtration, on membrane fouling are scarcely reported. In this research, we studied the effect of coagulation as a pretreatment process of the ceramic membrane filtration system, with the focus being concentrated on investigation of the effect of Gt value of coagulation through experiments of membrane filtration after precoagulation. The results indicate that; the difference in the increase rate of transmembrane pressure depends on the Gt-value of coagulation. The optimum Gt values seem to be existent in the range of 20,000-50,000. Optimization of the Gt-value contributes to suppression of the increase rate of the transmembrane pressure, reduction of the coagulant dosage and reduction of pH control chemicals.
施設園芸栽培では，塩類集積を防ぐ目的で休閑期間に除塩灌水を行う．しかし，商品作物栽培後に栄養塩が土壌に残留していると，灌水とともに溶脱した栄養塩が水質汚濁の原因になる．本研究では，ナス施設栽培農家実圃場の休閑期を対象に，クリーニングクロップ栽培が休閑期（クリーニングクロップ栽培，除塩灌水，土壌還元消毒）の窒素，リン溶脱に与える影響を2年間調査した．その結果，クリーニングクロップによって，休閑期の窒素溶脱量を2010年には12.2 g m-2，2011年には5.4 g m-2削減できた．この違いはクリーニングクロップ栽培前に土壌中に残存していた無機態窒素の差によるものと推察された．一方，リンに対しては，クリーニングクロップを栽培しても溶脱量は有意に低減しなかった．これは，クリーニングクロップのリン吸収量に比べて，供試圃場の土壌リン酸蓄積量が非常に多かったためと考えられる．
The aim of this study was to evaluate the feasibility of rapid vermicomposting of different fresh fruit and vegetable wastes (FVWs) including banana peels, cabbage, lettuce, potato and watermelon peels using earthworm Eisenia foetida. For this, the changes of physicochemical properties, microbial profiles and earthworm biology were comprehensively evaluated after vermicomposting for 4 weeks. Compared to controls (without earthworms), vermicomposting caused reductions of the total carbon content by 42.7-52.4% and the carbon to nitrogen ratios by 46.5-61.1%, and increases of the electrical conductivity by 6.7-69.4% and the total phosphorous content by 4.0-52.0%. Vermicomposting revealed a higher microbial activity, density and diversity in end products than controls. The vermicomposting treatment for FVWs allowed a high growth rate of earthworms and an increased number of cocoons. Similar microbial community structures were observed in all vermicomposts, indicating a high degree of bio-stabilization and maturity. The results suggest that rapid vermicomposting is a feasible technology for converting fresh FVWs into valuable products and that the quality of vermicomposts is strongly associated with the properties of initial substrates.
A new landfill settlement model is proposed by coupling microbiological kinetics to simulate and predict municipal solid waste (MSW) landfill settlement. The model can be used to evaluate the effect of bacterial metabolisms on MSW landfill processes including settlement. The model is based on three mechanisms, namely, biodegradation of organic carbon mass, stress variation and moisture removal from waste particles (IMR) and pore spaces. Model simulation indicates that the contribution from biodegradation is small within a short period of simulation time. The landfill settlement has been dominated with water removal induced settlement where landfilling solid waste has high percentage of biodegradables and moisture content. To examine and simulate MSW landfill settlement process, a lab scale column experiment was carried out with synthetic MSW. The observed MSW landfill settlement in column experiment was used to verify the proposed model. The simulation and experiments suggested that effect of water removal will influence primary stage of settlement and this process will be introduced as a new mechanism for landfill settlement modelling. However, a careful demarcation between mechanically induced settlement and effect of internal moisture present in waste particles has to be explained by considering absorptive properties of waste particles, level of compaction and age of the waste.
Understanding the effects of environmental conditions (e.g. temperature and pH value) on organic carbon dissolution behavior is very important for quantifying the biodegradation of municipal solid waste. However, the dissolving of organic carbon from solid waste has not been sufficiently described. In this paper, the dynamic of organic carbon dissolution under different temperature and pH value conditions are analyzed by both experiment data and model simulation. The results revealed that lower leaching pH values are favor for dissolving organic carbon especially rapidly dissolution fraction of the solid samples. Under high temperature extraction condition, the dissolution rate of rapidly dissolution fraction was also improved and the amounts of biodegradable products exceed low temperature extraction amount. The dissolving rates of organic carbon were in the order of 0.045-0.22 m3/kg/h for all leaching conditions. The labile fractions of water extractable organic carbon were ranged from 3.5% to 20.3%. Therefore, the water extractable organic carbon extracted from MSW consists of substantial amount of stable fraction, indicating that anaerobic bioremediation of old landfill site is ineffective.