Roles of acid-producing bacteria in anaerobic digestion of waste activated sludge

Three acid-producing strains, AFB-1, AFB-2 and AFB-3, were isolated during this study, and their roles in anaerobic digestion of waste activated sludge (WAS) were evaluated. Data of 16S rRNA method showed that AFB-1 and AFB-2 were Bacillus coagulans, and AFB-3 was Escherichia coli. The removal in terms of volatile solids (VS) and total chemical oxygen demand (TCOD) was maximized at 42.7% and 44.7% by inoculating Bacillus coagulans AFB-1. Besides, the optimal inoculum concentration of Bacillus coagulans AFB-1 was 30% (v/v). Solubilization degree experiments indicated that solubilization ratios (SR) of WAS reached 20.8%±2.2%, 17.7%±1.48%, and 11.1%±1.53%. Volatile fatty acids (VFAs) concentrations and compositions were also explored with a gas chromatograph. The results showed that VFAs improved by 98.5%, 53.0% and 11.6% than those of the control, respectively. Biochemical methane potential (BMP) experiments revealed that biogas production increased by 90.7% and 75.3% when inoculating with Bacillus coagulans AFB-1 and AFB-2. These results confirmed that the isolated acid-producing bacteria, especially Bacillus coagulans, was a good candidate for anaerobic digestion of WAS.

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A stage-structured, Aedes albopictus population model

Aedes albopictus has been the fastest spreading invasive animal species in the world from the mid-1980s until the mid-2000s. In areas it infests, it disrupts native mosquito ecology and can potentially vector up to 21 viruses. To better understand the population dynamics of this species, we created a temperature dependent population model. A stage-structured model was chosen to allow each life-stage to have different temperature dependent mortality and development rates, and each stage was modeled with an ordinary differential equation. Model parameters and distributions were based upon literature values. Initially, a basic model was constructed. This model then had parameters that were forced based upon daily average temperatures. Several criteria were used to evaluate the model, including a comparison to field data from Lubbock, TX. In a stochastic version of the model, a 95% confidence limit contained 70.7% of the field data points. Based upon these results, we feel reasonably confident that we have captured the role of temperature in driving the population dynamics of Ae. albopictus.     

基于垃圾焚烧锅炉入料口的风幕技术

分析了垃圾发电锅炉入料口的正压释放问题,设计的风幕技术保证了此类循环流化床锅炉的安全运行,风幕技术改造结构设计合理,实用性强,值得在同类行业中推广应用。     

微波密封消解法测定COD的关键操作技术

在水质监测及诸多行业的工业废水监测中,COD是一个必测项目,微波密封消解测定COD是一种新方法,此方法与国标(GBll914—89)重铬酸钾法回流测定COD相比,具有成本低、操作安全、快速便捷等优点,其测定结果同标准重铬酸钾回流法相比对线性相关系数r大于0.999,是值得推广使用的一种方法。但为了得到准确可靠的分析结果,提高测定COD的工作效率,必须严格把握好一些关键性的技术问题。     

Studies on solvent extraction of iron(III) as a step for conversion of a waste effluent to a value added product

Solvent extraction of iron(III) from actual sulphate waste pickle liquor was investigated using trialkylphosphine oxide diluted with kerosene. The waste pickle liquor was procured from a local company which deals with the manufacturing of pipes and tubes made of iron and steel. Various parameters were studied to optimise a suitable condition for the maximum extraction of iron. The composition of the aqueous feed used in the experiment was 60.88 g/L Fe(III), 53 g/L acid with traces of Cu, Ni and Co. An ambient extraction at 30 °C yielded acceptable kinetics and loading efficiency for 40% trialkylphosphine oxide with a saturated loading capacity of 51.85 g/L in four contacts at O/A ratio of 1/1 in a multiple contact mode. Iron from the loaded organic was stripped using various strippants such as distilled water, H₂SO₄ and oxalic acid. Since only 32% of loaded Fe could be stripped with 2 M H₂SO₄ in five contacts, further stripping was done with 5% oxalic acid which showed a very promising result. It was found that almost 100% of Fe(III) could be stripped out with 5% oxalic acid at O/A of 1/1 in five contacts.     

Personality, individual differences, and demographic antecedents of self-reported household waste management behaviours

The present study sought to extend recent conceptual frameworks of waste management behaviours by examining personality, individual differences, and socio-demographic antecedents of self-reported waste recycling, reuse, and reduction behaviours. A total of 203 participants from a British community sample completed a questionnaire consisting of measures of their self-reported waste management behaviour, Machiavellianism, political cynicism, the Big Five personality traits, and socio-demographics. The results of structural equation modelling showed that individuals who were less Machiavellian, less politically cynical, older, and more conscientious were more likely to report positive waste management behaviours. In combination, these predictors explained 22.0% of the variance in waste management behaviours. Thus, these variables may improve the predictive validity of existing conceptual models of waste management behaviours. The results are discussed in relation to those models.     

Valorization of solid waste in sugar factories with possible applications in India : A review

Sugar production is a major agro-based industry in India that generates various solid wastes viz. sugarcane trash, bagasse, press mud and bagasse fly ash. This work examines the state-of-the-art in innovative value added products that can be obtained from the transformation of these wastes. Challenges in implementing these waste valorization solutions are also highlighted. It is observed that the extent of research and adoption of these solutions vary considerably. Both industry involvement as well as government encouragement is required in translating the research findings into commercial products.     

Predicting future quantities of obsolete household appliances in Nanjing by a stock-based model

China has become one of the largest producers of obsolete household appliances (HAs) in the world. However, information on discarded HAs in China is deficient owing to the unavailability of reliable data. The estimation of future obsolete streams is a crucial issue for the establishment of efficient waste collection and recycling systems. The present study describes a prediction model to forecast future obsolete HAs on the basis of information of in-use stocks of HAs in households. The model was applied to a forecasting analysis of quantities of obsolete HAs from 2009 to 2050 in Nanjing, China. The results show that a total of about 76 million units (2.8 million tonnes) of obsolete HAs will be generated in Nanjing over the next 40 years. Discarded air conditioners, color TV sets, and personal computers will be the major contributors. The total discarded amount of major kinds of HAs will increase from nearly 1.0 million units in 2009 to a maximum of 2.1 million units in 2040, and then decrease slightly to 2.0 million units in 2050. Urban households will generate significantly more obsolete HAs (about 56 million units) than rural households, due to the difference in their HA possession levels. The results of this study should help the Nanjing municipality to develop the collection and recycling systems and facilities needed for the obsolete HAs generated in the future. From a methodological perspective, the stock-based model provides a suitable tool to predict the generation of discarded HAs in the future.     

The causes of food waste in the supplier-retailer interface: Evidences from the UK and Spain

Food and drink waste is a significant problem for economic, environmental and food security reasons. Government efforts have focused on diverting waste away from landfill through regulation, taxation and public awareness. However, efforts to understand why waste occurs have been limited, particularly in the interface between retailers and suppliers. This research aims to address this problem by identifying the main root causes of waste in the supplier-retailer interface.The research is exploratory in nature as there is a paucity of studies focusing on food waste across the supply chain. Data were collected through 43 interviews with managers in food manufacturing, wholesaling and retailing in two countries: the UK (24) and Spain (19). Data from the interviews and supplementary documentation were analyzed using causal maps. This approach helped to identify the main root causes of waste which were categorized into three groups: (1) mega-trends in the marketplace, (2) natural causes related to the products and processes, and (3) management root causes on which practitioners have a direct impact.The paper discusses the root causes of food waste and good practices identified from the interviews. Differences between the UK and Spain are discussed, presenting potential learning opportunities for practitioners in these countries and highlighting opportunities for further research.