Advanced Materials Research Vols. 726-731

Abstract: The pyrolysis of sewage sludge (SS) in the presence of sewage sludge pyrolysis char (SSC) as catalyst was conduct in a horizontal reactor at 500°C. Gas chromatography-mass spectroscopy (GC-MS), element analysis, high heating value (HHV) analysis, water content analysis and gel permeation chromatography (GPC) were used to characterize the pyrolysis oil. The declined char yields with increased SSC mix ratio (MR) indicated that SSC could promote the devolatilization reaction. Meanwhile the declined top phase oil (TPO) yield and increased bottom phase oil (BPO) and gas yield showed that crack reaction may happen catalyzed by SSC. According to the result of GC-MS, aliphatics and steroids content drops apparently since MR increased to 50 wt.%, while aromatic compounds and phenols content increased at the same time. Element analysis showed an apparent transportation of hydrogen and oxygen from TPO to BPO. HHV of TPO decreased with MR increased. The result of GPC indicated that increased MR caused continuing decreased average molecular weight of TPO. Consequently, the increased SSC addition could promote the devolatilization and large molecular compounds catalysis crack of sewage sludge.

Abstract: Based on the condition test and comparative analysis of mixing bottom pot water and bottom cellar water from a sauce sweet model liquor enterprise and a fen-flavor liquor enterprise, this study discuss the difference of recycling methane from anaerobic fermentation in two types of distilled spirit wastewater. The results of the tests show mixing the bottom pot water and bottom cellar water of the two kinds of Chinese spirits under the optimal proportion and conducting the anaerobic experiment under optimum conditions, the COD concentrations in effluent of both mixed distilled spirit wastewater are approximately the same. And the rates of degradation in two types of wastewater are almost the same. At the same time, the gas production of sauce sweet model liquor wastewater is a little higher than that of fen-flavor wastewater. The best removal rates of COD are 90.22% and 88.99% respectively for the two types of wastewaters.

Abstract: There are two main waste-to-energy (WtE) ways to treat municipal solid waste (MSW) in China: incineration with electricity and landfill with landfill gas utilization. And the calculation methods provided by Intergovernmental Panel on Climate Change (IPCC) Guidelines are often used for calculating greenhouse gas (GHG) reduction of WtE. This paper compared the GHG emission reductions of the two WtE methods, and made a cost-benefit analysis of them. Results show that: incineration with electricity can reduce more GHG emission than landfill with landfill gas utilization while disposing of 1 t MSW and the cost of incineration is higher than landfill while reducing 1 t CO₂eq.

Abstract: Based on cooperative game theory, this paper, after taking government subsidy into consideration, analyzes, from the two aspects of waste collection cost and disposal cost, the cooperative game relation between manufacturers and resource recovery companies in the process of recycling of industrial zone wastes as well as the important role that government plays in the recycling cooperation mechanism established between the two sides. After calculation of payoff matrix, it is found out that the difference between manufacturers self-disposal cost and entrusted disposal cost, resource recovery companys waste recovery cost and disposal cost, and government subsidy are the key factors that decide whether the two sides will cooperate with each other. Finally, the paper proposes the measures that will facilitate the cooperation of the two sides, which is of certain guiding significance to build an eco-friendly supply chain and boost the development of circular economy.

Abstract: The coal fly ash (CFA)/coal fly ash modified by sulfuric acid (MCFA)-conditioned sludge dewaterability was investigated in this study. Specific resistance of filtration (SRF) was used to assess the sludge dewaterability. Extracellular polymeric substance (EPS) was determined in attempt to explain sludge conditioning process. The results showed that SRF of the sludge significantly decreased with coal fly ash addition, and the MCFA showed much stronger conditioning capacity than the raw coal fly ash. Under a MCFA dosage of 36g.L^-1, the SRF of the sludge decreased from 1.18×10¹² to 6.47×10¹⁰ m.kg¹, and EPS concentration of the sludge decreased from 32.64 to 17.55mg.L^-1. The sludge conditioning mechanisms with MCFA mainly included improving adsorption bridging and providing the water transmitting passages by skeleton builder.

Abstract: Pickling is a necessary process in many metal processing industries, such as wire rod, iron and steel sheet plate, and tubing processing industries, screw and nut manufacturing and processing industries, corrosion resistant plate processing industries, and paint industry. Pickling is used to remove black rust, oxides, and other contaminants from metal surfaces in order to improve processing quality. Hydrochloric acid is often used in the pickling process. As the acid concentration decreases gradually during the process, while metal (Fe and Zn) concentrations increase gradually, when the residual concentration of hydrochloric acid in the spent pickle liquor decreases to about 3%, or the specific gravity of spent pickle liquor is greater than 1.3 (iron ion concentration is greater than 100g/L), the aged pickle liquor must be discharged and fresh pickling solution is prepared. In the wire rod industry in Taiwan, the pickling process results in highly corrosive spent pickle liquor. Although there have been multiple resource processing schemes developed, including spray roasting process, fluidized bed roasting process, and sulfuric acid displacement process, it is limited to various factors, such as the treatment capacity, initial cost, operating cost, selling prices, purity of recycled products, and market scale. This study reviewed related patented processing modes in literature, and considered the reclamation cost of waste pickling solution (SPS). The proposed technique adopts wet-process metallurgy, combined with diffusion dialysis, for reclamation of SPS and mineralization crystallization of heavy metal of residue iron. The mineralization crystallization treatment produces high-purity recycled products of ferrite and goethite processes. SPS is reclaimed, and the ferric heavy metal recycling meets the economic benefit of an actual plant. The research site of this study produces 12 tons of SPS per day, which is about 300 tons monthly, and about 3,600 tons annually, with the removal cost of 7.2 million NTD annually. If the proposed treatment system is adopted, the costs of fresh hydrochloric acid, removal, and the traditional neutral agent treatment and subsequent landfill could be greatly reduced, thus effectively reducing the environmental load. In comparison to other recycling treatment techniques, the main advantage of the proposed technique is that the treatment capacity depends on the amount of SPS, the energy consumption is relatively low, the treatment scheme is simple, the operating and maintenance costs are low, and the mineralization can produce magnetic ferrite and iron oxide recycled products with high purity.

Abstract: Effects of two types of biochars from wheat straw (SB) and hard miscellaneous woods (WB), combined with two types of soils on the growth and yield of wheat were evaluated to identify biochar addition to suitable soils on crop yield for accelerating biochar application. Plant growth variables and yields were studied in order to assess the agronomic efficiency of biochar. Our results showed that both biochar additions to an alkaline soil had little or negative effect on plant growth and wheat yield. However, to neutral soil, addition of both biochars could improve plant growth and increase significantly the wheat yield. There were significant differences on effective spikelet, number of seeds, above ground biomass and no significant differences on total spikelet, TKW among different treatments which SB was applied in neutral soil, whereas there were no significant differences on any aforementioned index at application of WB in neutral soil. Further analysis indicated that effect of SB on yield was better than that of WB, and 6% SB and 2% WB were the best for neutral soil respectively.

Abstract: Calcium(Ca²⁺) and magnesium(Mg²⁺) ions dissolve out in the process of getting phosphorus-rich solution by hydrolysis and acidification of sludge. To study the effect of dissolved Ca²⁺ and Mg²⁺ on nitrogen and phosphorus recovery, this paper investigated the dissolution of NH₄⁺, PO₄^3-, Ca^₂+ and Mg²⁺ in the process of hydrolysis and acidification of excess sludge under the condition of different pH and discussed the impact of Ca²⁺ and Mg²⁺ ions on the recovery of nitrogen and phosphorus by struvite precipitation method. The result indicates that the adjusting of acid-base environment can contribute to the release of NH4⁺-N and PO₄^3--P in the process of hydrolysis and acidification and pH=3 is the best and the best reaction time is 5 days. The fact that the molar ratio Ca²⁺: Mg²⁺ is greater than 1 has influence on nitrogen and phosphorus recovery but whether additional magnesium existed or not has little effect on the percent recovery of nitrogen and phosphorus when pH=3.

Abstract: The sintered brick was prepared with combining red mud and sale, as well as the sintered activation materials that were some industrial wastes. The effects of red mud content on property of sintered red mud-shale brick would be researched in this paper. The results showed when the ratio of red mud : sale : the sintered activation materials was 50:35:15, the sintered brick could meet the requirements of grade-A according to GB5101-2003, and the compressive strength reach MU25. The XRD showed that the main ingredient had been transformed into stabilized gehlenite, wollastonite and nepheline, as well as more glass phase and remained quartz.

Abstract: Ecologic environment is increasingly polluted, amount of green consumers are expanding, and more countries and governments have enacted and implemented environmental protection regulations to curb firms environmental negative impact. Based on product life cycle return perspective, we divide returns into three types: beginning of life return, end of use return and end of life return. Then, we analyze return value evaluation through law of conservation and conversion of energy. Our conclusions show for between beginning of life and end of use product return, educating consumers environmental conscious and responsive collection and resell returned products measures are the core ingredients. For after end of life product return, the best strategy is that firm collects and disposes in cost efficient measures replacing consumers direct disposal.