Hong Kong recently opened a state-of-the-art sewage sludge waste treatment plant, reducing by up to 90% the volume of landfilled sludge waste, while concerting a net energy benefit equivalent to the daily requirement of 4,000 households. The project, in addition, provides a range of ecologically friendly features, from emission reducing technologies to awareness raising techniques. Arup is the principal designer of the project - of which the value of the contract has not been disclosed.
The waste-to-energy plant seeks to solve a number of problems resultant from the production of large amounts of human waste, of all kinds. The technology uses a range of techniques to incinerate, compost, or otherwise convert energy stored in waste into useful energy, in the form of electricity.
The technology can be applied to solid waste, otherwise destined to fill space in a landfill, is now converted to heat instead – with a net positive energy result. The technology provides a range of advantages, from creating value for what would otherwise be a cost, to reducing the space required for overall waste. However, the kinds of waste dumped in landfills are not all equally combustible.
One traditionally less than combustible material is foul wet sludge, derived in the process of dealing with raw sewage at sewage facilities. Traditionally, sewage is treated before being dispersed, with the resulting sludge dumped in landfills. New technologies are, however, reducing the space required to store the sludge, which is turned to ash, and produce a large amount of electricity. A recent project that leverages newly developed sludge to electricity technology is in Hong Kong: the sludge waste-to-energy plant was recently completed and converts sludge waste from 11 of the mega city’s sewage waste plants into electricity.
The facility, called T·Park, will, when it is fully operational, be able to treat up to 2,000 tons of sludge on a daily basis. The combustion process produces slightly more energy than is required to operate the process, resulting in a net megawatts of surplus energy to power around to 4,000 households. Additionally, the system will reduce the total landfill waste volume by around 90%.
Arup was one of the chief professional services firms, called in in 2011 as the principal designer for the Veolia-Leighton-John Holland joint venture. The firm, for an undisclosed sum, provided services including detailed engineering design for all civil, structural, geotechnical and building services associated with the buildings, mechanical and electrical engineering as well as fire engineering for the project.
Waste produced from the plant itself, in the form of emissions, will also be treated – using a range of flue gas treatment methods for which outputs will meet environmental standards. The park as a whole will meet the stringent BEAM Platinum rating, and incorporates technologies that include large green spaces (up to 70% of the facility is to be covered in greenery); wastewater is treated and reused for irrigation, flushing and cleaning purposes; and a seawater desalination plant produces fresh water for use on-site, while rainwater is collected for non-potable use. In addition, a range of educational activities will be hosted onsite to enhance environmental awareness and education.