Applied Mechanics and Materials Vols. 295-298

Abstract: A pilot scale experiment of composting in rotting boxes used pig manure with cornstalks was carried out to study the effects of superphosphate on nitrogen and carbon losses including gas emissions. Besides control, there were five amended treatments with superphosphate addition (counted by P content) at 0.05, 0.10, 0.15, 0.20 and 0.25 molar ratio of initial nitrogen. The results indicated that superphosphate addition decreased ammonia volatilization, total nitrogen and carbon losses in composting. Total nitrogen losses of superphosphate-amended treatments were reduced by 9.3%, 14.6%, 30.1%, 45.8% and 71.5%, respectively. About 0.8% to 1.2% of initial nitrogen lost in the form of N2O emission, and the CH4 emission accounted for less than 0.3% of initial carbon. More than 0.15 molar ratio of superphosphate in compost materials caused considerable adverse effects on degradation of organic matter.

Abstract: A single-phase reactor was applied to food waster digestion for hydrogen production in order to test its feasibility. Different solid retention time (SRT) and pH adjustment modes were tried in a series of semi-continuous experiments. The results showed that it was necessary to take some precautions including a long SRT and a proper pH adjustment mode so as to avoid the excessive acidification in single-phase digesters. When lime milk was added into the digester to adjust pH to about 7 once a day, the food waste digester, which had a SRT of 20 days and a feed concentration of 4%, can produce hydrogen steadily. The hydrogen content was 27.6-51.3% and the degradation rate of food waste organic matter was 54%.

Abstract: In order to optimized the process parameters of Hydrothermal Process for Restaurant Garbage, a set of U24(63) uniform design trial tests were implemented. The results showed that the optimal condition for preparing feed from restaurant garbage is being heated for 80 minutes at 120 °C with water addition ratio on 30%. Additionally, hydrothermal treatment can kill bacteria thoroughly and affect the dewaterablity of the garbage markedly. Furthermore, hydrothermal process improvs the de-oil performance of the garbage, and the optimal conditions for de-oil is being heated for 80 minutes at 160 °C.

Abstract: Detailed investigations on the physical composition and properties of MSW in the experimental districts revealed that high moisture and high percentage of kitchen waste are the main limiting factors in the recovery of recyclables. A new category classified system, according to which MSW was classified as kitchen waste, other waste and ash waste, was proposed of South Beijing. In addition, a corresponding MSW treatment pattern that involves all compost for kitchen waste, incineration for other waste and landfill, for ash waste and residues of composting and incineration were constituted to promote efficiency of waste disposal. The recycling rate, benefit cost ratios and the production rate of compost were improved about 65.0%, 31.6% and 82.9%, respectively. But the landfill capacity was reduced by 81.6% for the category classified MSW as compared with mixed collected pattern.

Abstract: The urine-diverting toilet separates the urine and faeces and collects urine alone at the source. This technique can not only collect and make the most use of nutrients in urine, but also reduce the pollutants load on water bodies. Because of the valuable benefits of urine-source separation system, many researchers have done a lot of study in the global scope and obtained many results on this techniques. Currently studies focus on extracting struvite precipitation from urine which can synchronously recover nitrogen and phosphorus. Because phosphorus is a scarce resource and most phosphate resources are going to the bottom of sea. The recovery of struvite can realize the sustainable utilization of phosphorus resources. This paper reviews the latest research outcomes on urine diverting and treatment techniques.

Abstract: Asbestos was widely used in numerous materials and building products duo to its desirable properties. However, it is well known that asbestos inhalation causes health damage and its inexpensive decomposition technique is necessary to be developed for pollution prevention. Dichlorodifluoromethane (CCl2F2) must be decomposed before being liberated into the atmosphere. Acidic gas (HF and HCl) generated from the decomposition of dichlorodifluoromethane (CCl2F2) in the presence of water vapor and oxygen, was reacted with chrysotile-asbestos fibers. At high temperature beyond 300 °C, chrysotile-asbestos fibers were completely decomposed, and sellaite and hematite were detected in the decomposed products.

Abstract: Impact of macro-organisms in biological processes had been considerably studied but some of the discrete interactions that exist between macro- and micro-organisms still remain complex and sometimes elusive. Agro-waste is a type of waste that remains highly inevitable in our society and its disposal is a subject of concern. Therefore, this study aimed to degrade sugarcane bagasse which is a significant agro-waste in Malaysia, while trying to understand the interaction between microbes and earthworm utilized in the bioprocess. Sugarcane bagasse was blended with spent tea in equal ratio before composting with the aid of Eudrilus eugeniae and introduced microbial consortia. Though varied, pH values across the amendments tended towards alkaline state, just as the available Phosphorus (P) and exchangeable Potassium (K) increased in the value. Total organic carbon (TOC) across the amendments showed reduction in value; 47% in TS (tea and sugarcane bagasse), whereas 25% in TS6M (Tea + sugarcane bagasse + 6 microbes) and 68% in TS3M (tea bagasse + 3 microbes). However, weight loss in Eudrilus eugeinae was found to be proportional to the reduced time of degradation. TS3M at 33% worm weight loss was recorded at 11 day degradation time, than TS6M (27%) and TS (16%) that showed 13 and 20 days degradation time respectively. Weight loss in earthworm is correlated with microbial interaction and can be a reflection of rate decomposition of organic components of agro-waste in a vermicomposting process.

Abstract: The issue of waste management has been a social and political priority for many years. Different experiences show what benefits can be obtained through interventions that reduce waste or foresee some mechanisms for reusing and recycling. In this context, the paper presents the results of a project financed by the EU LIFE + fund, dedicated to the creation of chains of secondary raw materials. The paper shows the methodology used and the results achieved in the project. In particular the chain for the recovery of olive oil mill wastes is presented. A feasibility study for a recovery facility is performed, confirming the profitability of the proposed technology and the goodness of the design methodology.

Abstract: The effects of sewage sludge addition on Huainan coal ash fusion characteristics were investigated by X-ray fluorescence (XRF) and X-ray diffraction (XRD). The experimental results showed that the ash chemical composition of Huainan coal ash was rich in SiO₂ and Al₂O₃, while the mass fraction CaO in sewage sludge was over 40%. Accordingly, the ash melting temperature of Huainan coal was higher than 1500°C while that of sewage sludge was lower than 1250 °C. The ash melting temperature of coal blending with sewage sludge fell with increasing mass fraction of sewage sludge in the range between 0 and 0.7. The aluminosilicate clay minerals with high fusion temperature contained in Huainan coal can be bond with CaO and iron oxides rich in sewage sludge forming low temperature eutectic system, it led to the reducing fusing temperature of Huainan coal mixing with sewage sludge.

Abstract: A series of experiments were carried out aiming at resource utilization of fresh green waste and sewage sludge. The green waste, rice straw and sewage sludge were chosen as raw materials and packing materials in composting experiments to study the variation characteristics of composting in different aeration patterns. It was found that the effect of intermittent aeration pattern during composting was better than continuous aeration pattern according to the results of detection of composting temperature, oxygen, carbon dioxide.