The Institute of Applied Science and Technology (IAST) has continued to increase the number of products it produces from recycling waste: from biodiesel and rubberised asphalt cement to roof tiles and is pursuing several options for commercializing,
During a recent tour of the facility, Director of the IAST Dr Suresh Narine revealed some of the recycling procedures and activities being undertaken by the institute, a report from Clean and Green Guyana/ Guyenterprise said. According to the professor, rice and food commodities industries generate a significant amount of unused by-products which IAST has found useful in the manufacturing of value-added food and feed products. These by-products are being used to make various noodles, cereals and risotto, which is made from broken rice which will be produced on a commercial scale, while other local materials are being combined to make nutritionally enhanced aquaculture feed.
$35M saved
Since 2006, the institute has been processing waste frying oils into bio-diesel. “Prior to our process, waste oil would end up in the drains, leading to clogging due to precipitation and foaming and also leading to increased biological oxygen demand, which occurs when materials are present that bacteria can consume in the drains: the bacteria proliferates and when they do that, the bacteria also consume increased amounts of oxygen, which decreases the amount of oxygen available to other aquatic organisms – the results are that the other organisms die and the drains begin to smell,” Dr Narine explained.
According to the professor, waste material that would normally end up in the drains now goes through a process of filtration, it is then heated and chemically processed into fuel that meets and exceeds American and German standard requirements for biodiesel. This recycling process allows the institute to save up to $35M in diesel annually. However, this commodity is not produced on a commercial scale due to the limited amount of waste available. In addition, the IAST built a commercial biodiesel plant in Wauna, Region One, to process palm oil into biodiesel.
Soaps, sanitizers and tiles
Glycerol, a by-product of the biodiesel process, is also recycled. It is combined with sawdust and used to fuel the boiler used in the process, instead of wood. Purified glycerol is also used in another of the institute’s projects; to produce liquid soaps and hand sanitizers.
High-density polyethylene, low-density polyethylene and polypropylene (specific types of plastic) are also recycled and transformed into roof tiles by combining it with up to 50 per cent waste from the sawmilling (sawdust), sugarcane (bagasse) and rice milling (rice husks) industries. The tiles are a high-value product which is significantly cheaper to manufacture than asphalt shingles and other high-value roof construction materials. The institute is currently seeking to commercialize the process, which includes extrusion and injecting moulding.
“We don’t utilize PET (Polyethylene terephthalate) because its melting temperature is very high and it’s hygroscopic, meaning that it absorbs water so when you heat it up in an injection moulder, because its melting temperature is higher than the temperature at which water boils into steam, the absorbed water becomes steam…which can be really problematic and unsafe,” the professor said. While this process can also generate other artefacts, roof tiles were chosen to meet the current boom in Guyana’s construction industry.
Biogas street lamps
IAST is also undertaking a project to combine animal waste with antelope grass (which clogs our waterways) to produce biogas to provide power for street lamps. The institute already has an operational bio-reactor which currently powers biogas-fuelled lamps in its own compound.
However, it is currently in discussions with the University of Guyana (UG) to construct a large biogas reactor, to power all of the campus’ street lights, “because they spend about …$1M a month to power all their street lights and our solution would also allow them to effectively deal with their waste issues.”
Recycling rubber
The institution also operates a rubber recycling plant which produces rubberized asphalt cement. “Tyres are debeaded, shredded and then granulated…the metals and nylons are separated and the rubber components are granulated into crumb rubber – 0.4 mm or less in particle size,” Dr Narine said. “We then use a chemical process to react the crumb rubbers at a high temperature with bitumen, which creates a product called rubberized asphalt cement.”
This material is used to coat the Demerara Harbour Bridge and other steel bridges. It is adhesive, elastic, provides extra traction and is safer and longer lasting than materials currently being used. This year, the IAST has arranged to acquire a mobile asphalt plant to allow the rubberized asphalt cement material to be applied to the bridges on location, since previously the plates had to be removed from the bridge and taken to the institute to be coasted.
The IAST also produces biomass briquettes from rice husk, sawdust and bagasse, which was commercially tested at the Enmore Sugar Factory. “The findings were amazing – equivalent weights of briquettes made from waste produced significantly more energy than the firewood that is currently being utilized by the factory,” Dr Narine said. The institute is on the verge of commercializing this project, as it has secured an industrial partner.
