Optimal sequence of landfills in solid waste management

Given that landfills are depletable and replaceable resources, the right approach, when dealing with landfill management, is that of designing an optimal sequence of landfills rather than designing every single landfill separately. In this paper we use Optimal Control models, with mixed elements of both continuous and discrete time problems, to determine an optimal sequence of landfills, as regarding their capacity and lifetime. The resulting optimization problems involve splitting a time horizon of planning into several subintervals, the length of which has to be decided. In each of the subintervals some costs, the amount of which depends on the value of the decision variables, have to be borne. The obtained results may be applied to other economic problems such as private and public investments, consumption decisions on durable goods, etc.

Improving waste management in construction projects: an Australian study

Construction waste generation has been identified as one of the major issues in the construction industry due to its direct impacts on the environment as well as the efficiency of the construction industry. As the industry cannot continue to practice if the environmental resources on which it depends are depleted, the significance of waste management needs to be understood in order to encourage stakeholders to achieve related goals. Therefore, this research aims to determine effective approaches to eliminate and/or minimise waste generation in construction projects. Mixed methods were adopted by combining qualitative and quantitative research approaches. Interviews and a questionnaire survey were conducted as the primary data collection methods. The findings reveal twenty six critical solutions for waste management. Five factors of solutions for waste management were extracted from the exploratory factor analysis. These factors were: team building and supervision; strategic guidelines in waste management; proper design and documentation; innovation in waste management decisions; and lifecycle management. The evidence from this study suggests that both technologies and attitudinal approaches require improvement to eliminate/minimise waste generation in construction projects. Similarly, attention should be paid to being mindful of the environmental effects of waste generation and avoiding waste generation as early as possible in construction projects.

Attitudinal and behavioural approaches to improving waste management on construction projects in Australia: Benefits and limitations

This research aims to understand the attitudes and behaviours of stakeholders towards waste management and consequently identify ways of improving waste management practices in construction projects. Semi-structured interviews were conducted. The findings reveal that most of the decisions in construction projects are based on their financial returns unless there is a special requirement to comply with Green Star or any other sustainable building rating system. Even though there is a trend towards environment-friendly construction, contractors are favourable towards methods involving financial incentives. Results also indicate that private developers are more price-driven compared with government clients. Findings reveal the necessity of enforcing legislation to improve waste management practices until such practices become culturally embedded in organizations across the supply chain. Similarly, end users' motivation towards waste management was also identified as a key to encouraging stakeholders of construction projects and improving their attitudes and behaviours towards waste management practices.

Waste management practices in construction projects: perceptions of project managers

The construction industry has been found to be a major generator of waste and there are many challenges associated with finding the most sustainable way to manage construction waste. As the construction industry is a project based industry, it is essential to look at cultural issues related to waste management at the project level. Therefore, this research aims to identify the current status of waste management practices in construction projects by analysing project managers’ views on waste management performance in construction projects; project managers’ attitudes towards waste management; and project managers’ views on waste management culture in construction projects. A questionnaire survey was carried out and project managers were selected as a target group to distribute questionnaires, as project managers have a vital involvement in promoting and maintaining project culture in the construction project environment. Data was analysed using descriptive statistics and the Kruskal-Wallis test. The findings reveal that project managers believe that even though the operational cost of waste minimisation is high in construction projects, overall waste management is profitable. At the same time it was interesting that even though project managers believe most project participants are satisfied with existing waste management systems, overall waste management efforts are not perceived as being at a satisfactory level in construction projects. Project managers consider waste as an inevitable by-product, but they do not believe that waste management is beyond the control of project members or that waste has no value. At the same time, it was found that project managers infer that project participants are cost and time conscious in waste management despite the roles, responsibilities and duties of each party in waste management not being well-coordinated or fully understood. Taken together, these findings highlight the misconceptions related to waste management in construction projects and emphasise the necessity of collective responsibility on the part of project participants to enhance the performance of waste management in construction projects.

Capacity building for post disaster construction and demolition waste management: a case of Sri Lanka

Purpose – The purpose of this paper is to present a theoretical framework for capacity building in post disaster construction and demolition (C&D) waste management at a national level to address the identified capacity gaps in managing disaster waste resulting from natural hazards.

Design/methodology/approach – Data were gathered through pilot interviews, case studies and expert opinion surveys representing government, non-government and other sector organisations involved in post disaster waste management.

Findings – The study revealed unavailability of a single point of responsibility and provision for disaster waste in existing policies and capacity constraints in prevailing peace time solid waste management practices which were identified as major capacity gaps. Establishment of a regulatory body and enforceable rules and regulations with necessary levels of capacities was identified and presented in a theoretical framework comprising of seven identified areas for capacity building in post disaster waste management.

Research limitations/implications – This study is limited to disaster C&D waste as debris generated from totally or partially damaged buildings and infrastructure as a direct impact of natural hazards or from demolished buildings and infrastructure at rehabilitation or early recovery stages. Waste generated during reconstruction phase of post disaster management cycle is not considered as disaster C&D waste for purposes of this study.

Originality/value – The research enabled analysis of existing capacities and presents approaches for capacity building for identified gaps in post disaster C&D waste management to attain sustainable post disaster waste management for future resilience.

Capacity gaps in post disaster construction & demolition waste management

Purpose – The purpose of this paper is to focus on the identification of the existing capacities of post disaster C&D waste management in developing countries, with a special emphasis on Sri Lanka to determine the capacity gaps and related influencing factors.

Design/methodology/approach – Multiple case studies and expert interviews were conducted to gather primary information on the existing capacities of disaster C&D waste management. Three case studies, including 15 individuals and six experts representing government, non-government institutions and others, were selected.

Findings – The results revealed the existing capacities, capacity gaps and influencing factors for post disaster C&D waste management in the areas of skills and confidence building, links and collaborations, continuity and sustainability, research and development, communication andcoordination, organisational implementation and investment in infrastructure.

Research limitations/implications – This study limited disaster C&D waste to debris generated from totally or partially damaged buildings and infrastructure as a direct impact of natural disasters orfrom demolished buildings and infrastructure at rehabilitation or at early recovery stages.

Originality/value – The research enabled an analysis of existing capacities and identified capacity gaps in post disaster C&D waste management with influencing factors developing countries.

Post disaster construction & demolition waste management: a Sri Lanka case study

The increasing nature of impacts from disasters has made post disaster management a key area of concern. The management of disaster waste is revealed as an area of least concern yet it presents momentous challenges for those with inadequate capacities due to the large volume and hazardous constituents created, specifically in developing countries. This paper aims to report the findings of post-disaster waste management strategies and challenges identified in Sri Lanka. Data was gathered through interviews with government and non-government organisations at national and local level. The lack of an established hierarchy and single point of responsibility, mandatory and enforceable rules and regulations; inadequate capacity and funds, and lack of communication and coordination were identified as gaps in post-disaster waste management. This enabled the identification of post-disaster waste management strategies, highlighting gaps that need to be addressed for effective C&D debris management for Sri Lanka’s future resilience.

Phylogenetic and physiological characterization of a heterotrophic, chemolithoautotrophic Thiothrix strain isolated from activated sludge

The sheathed filamentous bacterium known as strain CT3, isolated by micromanipulation from an activated sludge treatment plant in Italy, is a member of the genus Thiothrix in the gamma-Proteobacteria according to 16S rDNA sequence analysis. The closest phylogenetic neighbours of strain CT3 are strains I and Q(T), which were also isolated from activated sludge and belong to the species Thiothrix fructosivorans. These strains have respectively 99.2 and 99.4 % similarity to CT3 by 16S rDNA sequence comparison. CT3 shows 63-67 % DNA-DNA hybridization with strain I, which is the only currently viable strain of T. fructosivorans. CT3 is the second strain in the genus Thiothrix that has been shown to be capable of growing autotrophically with reduced sulfur compounds as the sole energy source; autotrophy was also confirmed in strain I. The first reported chemolithoautotrophic isolate of this genus was a strain of 'Thiothrix ramosa' that was isolated from a hydrogen sulfide spring and is morphologically distinguishable from all other described strains of Thiothrix, including CT3. CT3 is an aerobic organism that is non-fermentative, not capable of denitrification and able to grow heterotrophically. Autotrophy in the genus Thiothrix should be investigated more fully to better define the taxonomy of this genus.

The treatment of domestic wastewater using small-scale vermicompost filter beds

The aim of this study is to quantity the effect of filter bed depth and solid waste inputs on the performance of small-scale vermicompost filter beds that treat the soluble contaminants within domestic wastewater. The study also aims to identify environmental conditions within the filters by quantifying the oxygen content and pH of wastewater held within it. Vermicompost is being utilised within commercially available on-site domestic waste treatment systems however, there are few reported studies that have examined this medium for the purpose of wastewater treatment. Three replicate small-scale reactors were designed to enable wastewater sampling at five reactor depths in 10-cm intervals. The surface of each reactor received household solid organic waste and 1301 m(-2) per day of raw domestic wastewater. The solid waste at the filter bed surface leached oxygen demand into the wastewater flowing through it. The oxygen demand was subsequently removed in lower reactor sections. Both nitrification and denitrification occurred in the bed. The extent of denitrification was a function of BOD leached from the solid waste. The environmental conditions measured within the bed were found to be suitable for earthworms living within them. The study identified factors that will affect the performance and application of the vermicompost filtration technology. (C) 2004 Elsevier B.V. All rights reserved.