Landfill aeration in the framework of a reclamation project in Northern Italy

In situ aeration by means of the Airflow technology was proposed for landfill conditioning before landfill mining in the framework of a reclamation project in Northern Italy. A 1-year aeration project was carried out on part of the landfill with the objective of evaluating the effectiveness of the Airflow technology for landfill aerobization, the evolution of waste biological stability during aeration and the effects on leachate and biogas quality and emissions.The main outcomes of the 1-year aeration project are presented in the paper.The beneficial effect of the aeration on waste biological stability was clear (63% reduction of the respiration index); however, the effectiveness of aeration on the lower part of the landfill is questionable, due to the limited potential for air migration into the leachate saturated layers.During the 1-year in situ aeration project approx. 275 MgC were discharged from the landfill body with the extracted gas, corresponding to 4.6 gC/kgDM. However, due to the presence of anaerobic niches in the aerated landfill, approx. 46% of this amount was extracted as CH₄, which is higher than reported in other aeration projects. The O₂ conversion quota was lower than reported in other similar projects, mainly due to the higher air flow rates applied.The results obtained enabled valuable recommendations to be made for the subsequent application of the Airflow technology to the whole landfill.     

适合我国国情的城市生活垃圾处理方法

介绍了发达国家所采用的城市垃圾处理技术的原理及其优缺点，对适合我国国情的垃圾处理技术提出了建议。     

Study on the mechanical and environmental properties of concrete containing cathode ray tube glass aggregate

Cathode ray tube (CRT) glass is considered a hazardous material due to its lead toxicity. In addition, current disposal practices are being phased out due to their adverse environmental impacts. In this project, CRT glass was used as a fine aggregate replacement in concrete. Life-cycle material characterization was conducted by evaluating the durability and strength of the CRT-Concrete. Leaching tests were also conducted to investigate whether the material meets drinking water limits for Pb. Test results show that the plastic state of the CRT-Concrete was affected by the angularity of the glass particles. Moreover, the compressive strength of CRT-Concrete met and exceeded that of the control specimen. However, CRT-Concrete was susceptible to expansive alkali-silica reactions when more than 10% CRT replacement was used. Environmental leaching results show that lead concentrations from CRT-Concrete are below the drinking water limits depending on the CRT volume replacement and if biopolymers are used.     

Recovery of different waste vegetable oils for biodiesel production: A pilot experience in Bahia State,Brazil

In Brazil, and mainly in the State of Bahia, crude vegetable oils are widely used in the preparation of food. Street stalls, restaurants and canteens make a great use of palm oil and soybean oil. There is also some use of castor oil, which is widely cultivated in the Sertão Region (within the State of Bahia), and widely applied in industry. This massive use in food preparation leads to a huge amount of waste oil of different types, which needs either to be properly disposed of, or recovered. At the Laboratorio Energia e Gas-LEN (Energy & Gas lab.) of the Universidade Federal da Bahia, a cycle of experiments were carried out to evaluate the recovery of waste oils for biodiesel production. The experiences were carried out on a laboratory scale and, in a semi-industrial pilot plant using waste oils of different qualities. In the transesterification process, applied waste vegetable oils were reacted with methanol with the support of a basic catalyst, such as NaOH or KOH. The conversion rate settled at between 81% and 85% (in weight). The most suitable molar ratio of waste oils to alcohol was 1:6, and the amount of catalyst required was 0.5% (of the weight of the incoming oil), in the case of NaOH, and 1%, in case of KOH.The quality of the biodiesel produced was tested to determine the final product quality. The parameters analyzed were the acid value, kinematic viscosity, monoglycerides, diglycerides, triglycerides, free glycerine, total glycerine, clearness; the conversion yield of the process was also evaluated.     

Challenges when performing economic optimization of waste treatment: A review

Strategic and operational decisions in waste management, in particular with respect to investments in new treatment facilities, are needed due to a number of factors, including continuously increasing amounts of waste, political demands for efficient utilization of waste resources, and the decommissioning of existing waste treatment facilities. Optimization models can assist in ensuring that these investment strategies are economically feasible.Various economic optimization models for waste treatment have been developed which focus on different parameters. Models focusing on transport are one example, but models focusing on energy production have also been developed, as well as models which take into account a plant’s economies of scale, environmental impact, material recovery and social costs. Finally, models combining different criteria for the selection of waste treatment methods in multi-criteria analysis have been developed.A thorough updated review of the existing models is presented, and the main challenges and crucial parameters that need to be taken into account when assessing the economic performance of waste treatment alternatives are identified. The review article will assist both policy-makers and model-developers involved in assessing the economic performance of waste treatment alternatives.     

Contribution of cooperative sector recycling to greenhouse gas emissions reduction: A case study of Ribeirão Pires,Brazil

Solid waste, including municipal waste and its management, is a major challenge for most cities and among the key contributors to climate change. Greenhouse gas emissions can be reduced through recovery and recycling of resources from the municipal solid waste stream. In São Paulo, Brazil, recycling cooperatives play a crucial role in providing recycling services including collection, separation, cleaning, stocking, and sale of recyclable resources. The present research attempts to measure the greenhouse gas emission reductions achieved by the recycling cooperative Cooperpires, as well as highlight its socioeconomic benefits. Methods include participant observation, structured interviews, questionnaire application, and greenhouse gas accounting of recycling using a Clean Development Mechanism methodology. The results show that recycling cooperatives can achieve important energy savings and reductions in greenhouse gas emissions, and suggest there is an opportunity for Cooperpires and other similar recycling groups to participate in the carbon credit market. Based on these findings, the authors created a simple greenhouse gas accounting calculator for recyclers to estimate their emissions reductions.     

Chemical conversion of paper industry effluents into carboxymethylcellulose

The synthesis of carboxymethylcellulose was investigated using effluents containing short cellulose fibers. Carboxymethylcellulose was synthesized according to the slurry process using different amount of sodium hydroxide and different incubation times at 30 °C after the etherification reaction as variables. Characterization of the product was conducted by Fourier transformed infrared spectroscopy, X-ray diffraction, degree of substitution, average degree of polymerization, water imbibing capacity, color, rheological properties, apparent viscosity and trace elements content. Incubation time slightly increased the yield of the reaction and the degree of substitution during the first 12 h. The reaction yield and degree of substitution both decreased when the initially concentration of NaOH was increased from 7.0 g/mL to 10.5 g/mL. The carboxymethylcellulose obtained was darker and had lower hydration properties than commercial samples. Trace elements content suggests that the product could be only used in paint factories or building materials industries.     

Optimization of biodiesel production from the waste cooking oil using response surface methodology

In this research, transesterification of the waste cooking oil has been studied. Response surface methodology (RSM) based on Box–Behnken design was used to investigate the effects of the main operating parameters, including the methanol to oil molar ratio, catalyst concentration, and reaction temperature, on the biodiesel yield. The results revealed that the catalyst concentration is the most important parameter. The maximum biodiesel yield under the optimized conditions was 99.38 wt.%. Thermogravimetric analysis (TGA) was used for the determination of biodiesel conversion and the results were compared with that of gas chromatography (GC) analysis, showing a very small difference. Furthermore, an empirical quadratic equation has been presented to show the relation between biodiesel conversion and product viscosity.     

Kinetics of Solvent Blue and Reactive Yellow removal using microwave radiation in combination with nanoscale zero-valent iron

We investigated the efficiency and kinetics of the degradation of soluble dyes over the p H range 5.0–9.0 using a method employing microwave radiation in combination with nanoscale zero-valent iron(MW–n ZVI). The n ZVI particles(40–70 nm in diameter) were prepared by a liquid-phase chemical reduction method employing starch as a dispersant.Compared to the removal of Solvent Blue 36 and Reactive Yellow K-RN using only n ZVI,more rapid and efficient dye removal and total organic carbon removal were achieved using MW–n ZVI. The dye removal efficiency increased significantly with decreasing p H, but was negligibly affected by variation in the microwave power. The kinetics of dye removal by MW–n ZVI followed both an empirical equation and the pseudo first-order model, while the kinetics of dye removal using n ZVI could only be described by an empirical equation. It was also concluded that microwave heating of the dye solutions as well as acceleration of corrosion of n ZVI and consumption of Fe(II) were possible reasons behind the enhanced dye degradation.     

填埋场中多酚氧化酶活性测定条件优化

以填埋场垃圾为研究对象,在土壤酶测定方法为基础上,对垃圾降解过程中多酚氧化酶活性测定方法进行优化.通过单因素实验和正交实验确定最优反应条件,并验证其精确度及稳定性.最终确定垃圾降解过程中多酚氧化酶活性测定的最优条件为基质取用10 mL、反应温度为30℃、缓冲液为8mL、反应时间为1.5h、萃取剂量为20 mL、萃取时间为50 min,且优化后测定条件实验结果的RSD小于2.22％,测定结果较传统方法提高了41％ ～ 90％,说明优化后结果准确可靠,为垃圾中多酚氧化酶的活性测定提供了新的方法基础.