Urban cultivation in Accra: an examination of the nature, practices, problems, potentials and urban planning implications

The literature on urban farming in Sub-Saharan African cities reveals that most studies have been conducted in Eastern, Southern and Central African cities. A few have focused on West Africa, including Sierra Leone, Guinea Bissau, and Cameroon. In Ghana there is a paucity of information on urban farming. The purpose of this paper is to examine the status of urban cultivation in Accra, Ghana's capital, reviewing existing research, and to present new empirical findings on urban cultivation emphasizing on its history, nature, practices, problems, potentials and urban planning implications.     

粉煤灰在废水处理中的应用

介绍了粉煤灰的结构及物理化学特性，处理废水的机理，综述了国内外利用粉煤灰处理各种废水的最新研究成果。目前利用粉煤灰处理废水主要应用于城市污水、印染废水、造纸废水、制药废水、电废水、重金属废水及含酚、含氟废水的处理。同时介绍了几种粉煤灰改性的方法及应用前景。     

废锌渣制氯化锌的研究

讨论了利用废锌渣制备氯化锌的理论依据、工艺流程、影响因素及控制方法     

People and their waste in an emergency context: The case of Monrovia, Liberia

Liberia has gone through civil crisis for over a decade which has resulted in the destruction of infrastructure and disruption of basic services delivery particularly in Monrovia, the capital city. Most of the 1.3 million people living in Monrovia are without adequate environmental sanitation and waste management services which situation poses a serious health risk to the residents. The current waste management service coverage is less than 20% and disposal is by indiscriminate open dumping. In 2003, there were series of outbreaks of cholera epidemics in the city during which time a total of 26,651 cases were reported with many dying.The waste management plan was initiated as an exit strategy of UNICEF following an intervention response programme to assist the Monrovia City Corporation (MCC) whose capacity in this area had been crippled as a result of years of war, through the provision of support in solid waste collection and disposal.The objectives of the plan were to:

(a) Improve waste management services delivery in the city.

(b) Strengthen the ability of the MCC to plan and manage the waste services delivery.

(c) Enhance cooperation of service beneficiaries through comprehensive and effective health education and service promotional campaign.

(d) Enhance revenue generation and community participation through the promotion of private sector and CBOs/NGOs active involvement in the waste management service delivery.

The general methodology adopted for the assignment entailed the following:Desk study and review of existing reports on Water and Environmental Sanitation (WES) in Monrovia and other relevant literature, consultation with stakeholders, site visits and participatory planning which aimed at soliciting the opinions of the various stakeholders involved with the respective components to capture their aspirations and experiences. It also covered collection and analysis of available information and data to facilitate the plan preparation and facilities design.The three-phased strategy (short, medium and long term) covering a period of 10 years (August 2004–December 2014), recommended a combination of technical options for collection based on the pursuit of staged development to allow for the adoption of realistically attainable standards within a framework of continuous and systematic improvements as economic conditions improved and new knowledge gained through practice. The plan sought to blend the capacity within the City Corporation with that of the private sector and NGOs/CBOs to respond to the diverse service demands of the city taking into consideration housing and infrastructural conditions, service costs and cost recovery to ensure sustainability. It also identified sources of financing and allocated financing responsibilities to facilitate effective plan implementation.     

Community-based household waste management: Lessons learnt from EXNORA's ‘zero waste management’ scheme in two South Indian cities

This paper presents two case studies on the efforts by a community-based organisation to promote a sustainable integrated waste management system in Indian mega cities. This effort was initiated in 1989 by a local non-governmental organisation (NGO) called EXNORA and is based on a ‘zero waste management scheme’ set up, run and financed by the residents themselves. As this model has been widely quoted as successful, the study aims at learning from two communities implementing this model.Results are reported from a survey of the two schemes that used various tools to assess both their performance and sustainability in selected residential areas of two Indian cities, Chennai and Hyderabad. The results indicate limited success of the schemes both in saving a significant fraction of the generated waste from dumping, and in rehabilitating the local poor. However, they show that motivated individuals can successfully set up and manage waste collection systems that lead to overall environmental improvements. The differences in the two schemes reflect how the local assets and contexts impact on the success of the scheme. The scheme in a rich neighbourhood of Hyderabad was less ambitious in its overall objectives and focussed on the provision of a waste management service, using the opportunity to provide local employment to a socially deprived fraction of the population. The scheme in a middle-class area of Chennai, although pioneering in its approach, suffered from diseconomies of scale and lack of social integration, making it less viable in the medium to long term. Both schemes suffered from a lack of community involvement, motivation and political support, which threatens the long-term sustainability of the enterprise. The research concludes that the role that communities can realistically play in management of their own waste depends on the local context. The system advocated by EXNORA seems to require significant local resources, and political and technical support which are hard to find and sustain without strong local leaders. Another model set up in the city of Visakhapatnam is finally introduced as an alternative. This is based on triangular contracts between the municipality, the residents and micro-enterprises and may provide a good solution in dealing with the technical and commercial aspects which communities find difficult.     

平菇废料高产栽培鸡腿蘑(Coprinus comatus)技术研究

对平菇废料高产栽培鸡腿蘑技术进行了研究，结果表明，平菇废料经发酵后用于室外栽培鸡腿蘑是可行的，具有很好的经济效益、社会效益和生态效益．     

工业废水混凝沉淀的实验研究

通过对上海市杨树浦废水站工业废水的混凝沉淀实验研究，确定了废水混凝沉淀最适宜的混凝剂种类、最佳的混凝反应条件及最优的药剂投加量，这不仅能节省药剂、降低工程运行费用，而且还能在很大程度上提高水的混凝沉淀处理效果。     

Role of informal sector recycling in waste management in developing countries

Many thousands of people in developing country cities depend on recycling materials from waste for their livelihoods. With the focus of the Millennium Development Goals on poverty reduction, and of waste strategies on improving recycling rates, one of the major challenges in solid waste management in developing countries is how best to work with this informal sector to improve their livelihoods, working conditions and efficiency in recycling.The general characteristics of informal recycling are reviewed, highlighting both positive and negative aspects. Despite the health and social problems associated with informal recycling, it provides significant economic benefits that need to be retained. Experience shows that it can be highly counterproductive to establish new formal waste recycling systems without taking into account informal systems that already exist. The preferred option is to integrate the informal sector into waste management planning, building on their practices and experience, while working to improve efficiency and the living and working conditions of those involved. Issues associated with integrating informal recycling into the formal waste management sector are discussed.     

基于二阶段随机规划的城市医疗废弃物回收网络设计

城市医疗废弃物日益增加,且回收需求量受诸多因素的影响,难以准确预测,假定回收需求为确定值的医疗废弃物网络优化设计不能与实际需求相匹配。本文考虑了离散随机参数环境下,医疗回收网络设计中选址规划、分配计划及运输规划的协同优化问题,建立了以选址成本、运输成本最小为目标,设施与车辆能力限制为约束的二阶段随机规划模型。根据模型特点,设计了基于Benders decomposition的求解算法,同时,设计了一系列加速技术用于提高算法的求解效率。最后,以国内某城市医疗回收网络为背景设计算例,检验本文模型和求解策略的可行性和有效性。结果表明：相比确定性规划,随机规划的解能够节约总成本,结合一系列加速技术的Benders decomposition方法比CPLEX与纯的Benders decomposition更有优势。     

Sensitivity,uncertainty, and decision analyses in the prioritization of research

The evaluation of hazards from complex, large scale, technologically advanced systems often requires the construction of computer implemented mathematical models. These models are used to evaluate the safety of the systems and to evaluate the consequences of modifications to the systems. These evaluations, however, are normally surrounded by significant uncertainties related to the uncertainty inherent in natural phenomena such as the weather and those related to uncertainties in the parameters and models used in the evaluation.

Another use of these models is to evaluate strategies for improving information used in the modeling process itself. While sensitivity analysis is useful in defining variables in the model that are important, uncertainty analysis provides a tool for assessing the importance of uncertainty about these variables. A third complementary technique, is decision analysis. It provides a methodology for explicitly evaluating and ranking potential improvements to the model. Its use in the development of information gathering strategies for a nuclear waste repository are discussed in this paper.