A prototype plant which converts pig and cow manure into clean water could be key to solving the huge environmental problem of the disposal of some 300,000 tonnes of farmyard waste each year.
Developed abroad, the plant was brought to Malta for testing as part of a research project funded by an agency set up to oversee the governance of agricultural bio-resources (GAB).
The equipment is being tested in a farm on the outskirts of Mġarr and the feedback so far has been encouraging.
While it is still early days, it is estimated that an on-site facility needed to treat manure generated on a farm would cost around €200,000 and produce 60 per cent of the equivalent volume of waste into water. Moreover, part of the bi-product could be used as fertiliser and the rest as fuel for waste to energy plants.
From a wider perspective, having to dispose of less animal waste would mean less stress on the sewerage network and a significant boost to the circular economy – the term used to describe practices aimed to minimise waste and emissions while recycling as much as possible.
At present our priority is to demonstrate that the technology works
Project coordinator Chris Ciantar told the Times of Malta that once the trial period finishes, various water samples produced from the plant will be sent to Denmark for further analysis. This will certify that the product is not only fit for irrigational purposes, but under the right circumstances could be even used as a potable source.
The prototype plant consists of a two-stage filtering system which removes the coarse and then the fine solids from the manure. The mechanism works by subjecting waste to high pressure to remove objects larger than 2mm in diameter and finer material greater than 0.1mm.
The sludge is then fed into a reverse osmosis system, to be filtered by means of several layers of fine membrane. Contrary to conventional systems, this reverse osmosis vibrates in order not to clog the mechanism.
During a brief demonstration, it only took about five to 10 minutes to produce clean water from cow manure, which is even harder to filtrate than pig waste as it contains a high sludge content. However, the water would still need further filtration or polishing through traditional systems to remove invisible chemicals like ammonia.
Though there are government plans in the pipeline to construct a dedicated facility to process animal waste, at present this is still being disposed in designated areas of the domestic sewers. The waste is then treated at Ta’ Barkat or Taċ-Ċumnija plants prior to being discharged into the sea or used for irrigation purposes.
However, this results in high maintenance costs as a result of clogging both in the sewers and the treatment plants and is not in line with EU directives. This practice is also a major contributor to greenhouse gas emissions.
Mr Ciantar said a facility with a capacity to treat all of Malta’s farm waste would be much larger than the pilot plant tested, but at the same time would be much more cost effective than having small onsite plants. However, he noted that having more than one plant offers the advantages of less transportation of waste around the island.
“At present our priority is to demonstrate that the technology works. If we received the go-ahead, it would then be up to the government to decide which kind of infrastructure is best for the Maltese Islands,” Mr Ciantar told this newspaper.
This project is made possible through the ‘scheme for a Holistic Approach to the Sustainable Management of Livestock Manure and Slurry within a Circular Economy Context’ as issued by Malta Council for Science and Technology on behalf of GAB.
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