Energy from waste (EfW): a feasibility study on the economic and the environmental co-benefits of biogas production within rural communities

Energy from waste (E/W) technologies in the form o f biogas plants, CHP plants and other municipal solid waste (MSW) conversion technologies, have been gaining steady ground in the provision o f energy throughout Europe and the UK. Urban Waste Water Treatment Plants (UWWTP) are utilising much o f the same biochemical processes common to these E/W plants. Previous studies on Centralised Anaerobic Digestion (CAD) within Ireland found that the legislative and economic conditions were not conducive to such an operation on the grounds o f low energy price for electric and heat energy, and due to the restrictive nature o f the allowable feedstocks. Recent changes to the Irish REFIT tariff on energy produced from Anaerobic digestion; alterations to the regulation o f the allowable use o f animal by products(ABP); the recent enactment o f the Renewable Energy D irective (09/28/EC) and a subsequent review o f the draft Biowaste Directive (2001) required that the issue o f decentralised energy production in Ireland be reassessed. In this instance the feasibility study is based on a extant rural community, centred around the village o f Woodford Co Galway. The review found that the prevailing conditions were now such that it was technically and economically feasible for this biochemical process to provide energy and waste treatment facilities at the above location. The review also outlines the last item which is preventing this process from becoming achievable, specifically the lack o f a digestate regulation on land spreading which deals specifically with biowaste. The study finds that the implementation o f the draft EU biowaste regulations, with amendments for Cr and Hg levels to match the proposed Irish regulation for compost, would ensure that Ireland has some o f the most restrictive regulations in Europe for this application. The delay in completing this piece o f legislation is preventing national energy and waste issues from being resolved in a planned and stepwise fashion. A proposed lay out for the new Integrated Waste from Energy Plant (IW/EP) is presented. Budget economic projections and alternative revenue streams are outlined. Finally a review o f the national policies regarding the Rural Development Plan (RDP), the Rural Planning Guidelines (RPG) and the National Renewable Energy Action Plan (NREAP) are examined against the relevant EU directives.

An analysis of the use of photogrammetric sorting to audit construction and demolition waste production on site

This study analyses the area of construction and demolition waste (C & D W) auditing. The production of C&DW has grown year after year since the Environmental Protection Agency (EPA) first published a report in 1996 which provided data for C&D W quantities for 1995 (EPA, 1996a). The most recent report produced by the EPA is based on data for 2005 (EPA, 2006). This report estimated that the quantity of C&DW produced for that period to be 14 931 486 tonnes. However, this is a ‘data update’ report containing an update on certain waste statistics so any total provided would not be a true reflection of the waste produced for that period. This illustrates that a more construction site-specific form of data is required. The Department of Building and Civil Engineering in the Galway-Mayo Institute of Technology have carried out two recent research projects (Grimes, 2005; Kelly, 2006) in this area, which have produced waste production indicators based on site-specific data. This involved the design and testing of an original auditing tool based on visual characterisation and the application of conversion factors. One of the main recommendations of these studies was to compare this visual characterisation approach with a photogrammetric sorting methodology. This study investigates the application of photogrammetric sorting on a residential construction site in the Galway region. A visual characterisation study is also carried out on the same project to compare the two methodologies and assess the practical application in a construction site environment. Data collected from the waste management contractor on site was also used to provide further evaluation. From this, a set of waste production indicators for new residential construction was produced: □ 50.8 kg/m2 for new residential construction using data provided by the visual characterisation method and the Landfill Levy conversion factors. □ 43 kg/m2 for new residential construction using data provided by the photogrammetric sorting method and the Landfill Levy conversion factors. □ 23.8 kg/m2 for new residential construction using data provided by Waste Management Contractor (WMC). The acquisition of the data from the waste management contractor was a key element for testing of the information produced by the visual characterisation and photogrammetric sorting methods. The actual weight provided by the waste management contractor shows a significant difference between the quantities provided.

The production of vermicompost from dairy sludge and its value as a plant growth medium

Dairy sludge generated at Glanbia Ingredients Ltd., Kilkenny has up until now been landspread. This study investigated the feasibility of using earthworms to vermicompost the sludge as an alternative method of treatment. It was found that high levels of ammonia in the sludge led to earthworm fatality but that by manually aerating the sludge the ammonia could be volatilised or by adding zeolite the ammonia could be absorbed, thus solving the problem. In a medium scale trial, the earthworm species Dendrobaena veneta and Eisenia fetida dominated the polyculture. Earthworms grew and generated cocoons during vermicomposting. During vermicomposting no leachate was generated. Nutrient changes took place during vermicomposting. There were high levels of nitrate, increased calcium and sulphate in the vermicomposted dairy sludge. The amount of magnesium, potassium and chloride did not change, while phosphate was undetectable after vermicomposting. The levels of nitrate and phosphate were good indicators of the extent of vermicomposting. The vermicomposted dairy sludge provided improved growth and yields of radishes and barley compared to the dairy sludge and control. Compared to the vermicompost, the dairy sludge provided heavier ryegrass yields and more marigolds with larger flower diameters. Generally, it is the amount of phosphate in dairy sludge that dictates how much can be applied as a fertiliser on land. Vermicomposting reduced the amount of phosphate to an undetectable level but on the other hand created a problem of high nitrate levels. In a pot trial with grass grown in vermicompost the nitrate leached from the vermicompost. In field conditions the leaching of nitrate might occur and could cause an increased risk of contamination of groundwater and watercourses.