A system for dealing with municipal solid waste (MSW) using liquid anaerobic digestion (AD) technology has been developed by an Israeli company and is being rolled out worldwide.
Arrow Ecology & Engineering Overseas (1999) has patented the Arrow Bio MSW Recycling Technology. Its facilities provide a hydromechanical separation and preparation process which recovers 90% of recoverable materials.
The liquid anaerobic treatment produces rich biogas and soil amendment for agricultural purposes.
The company started developing the technology in 1995 by recycling one tonne a day. By 2003 it had achieved a daily recycled quantity of 200 times this amount. In 2006 this was increased to 300 tonne per line and, by 2008, upwards of 300 tonnes per day. Being a modular system, it is easy to expand plant size to meet production requirements.
In 2011 an extensive feasibility study was undertaken in Lagos, Nigeria, together with the state government and local partner Index Eko Sludge Technology.
Lagos has a population of 22 million and this is expected to increase to approximately 26 million by 2015. In January this year, Arrow began construction of the first of four 300-tonne a day plants with Index Eko.
Arrow Bio’s unique wet process, using hydromechanical separation of waste, has been welcomed by the state because it fits with its green strategy. The Nigerian government wants to reduce carbon emissions and create green electricity from the 10,000 tonnes of waste collected daily in Lagos.
With the Arrow Bio wet process for recycling, the light materials float and are removed, heavy materials fall to the bottom and are removed and the organic content is held in suspension and pumped to the digesters.
Methane is produced from the organic waste and turned into green electricity or biogas. The byproduct after methane production is a clean and rich fertiliser/soil amendment for farmers and market gardeners.
Arrow Bio plants recycle 85-95% of all MSW. There is no burning of waste so there are zero carbon emissions. Nor is there any contamination of the soil or water table, and no smell or dust.
The plants only require water when commissioned because they produce their own water from the organic content of the MSW. A 300-tonne a day plant will produce about 1.9MW/hr and uses about 0.6MW/hr to operate, the balance being supplied to the grid.
Arrow Bio has been welcomed in Lagos because up to 500 tonnes of rubbish per day will be diverted away from landfill for recycling. The city will benefit from the recycling and much-needed green electricity. People who live on the waste dumps and scratch a living from these sites will now be offered permanent employment in the Arrow Bio plant.
In time such plants could recycle all waste, and help to eradicate the smell of decaying rubbish at landfill sites in Lagos.
Bing Beghin, consultant at Eko Pantheon Technologies
Process comes to the uk
In the UK, councils are aiming to recycle 50% of MSW by 2020. Arrow Bio can achieve a recycling percentage in excess of 85% immediately and produce green electricity without any burning taking place. The company currently has plants operating in Israel and Australia. New orders have been placed for various size plants in India, China, Italy, Russia, Brazil and the US among others. Eko Pantheon has begun marketing the technology in the UK.