New Pharmaceutical Waste Management Technology
Pharmaceutical waste represents a highly toxic and recalcitrant waste stream that is currently entering our natural systems insufficiently treated and unmonitored, and negatively impacting our environmental health. Current practices involve autoclaving and disposal at dedicated landfill sites, resulting in toxic leachate. High-temperature incineration is the only effective way to deconstruct this toxic waste but it is not an option within New Zealand due to limitations imposed by the National Environmental Standards for air quality.
We use catalytic hydrothermal deconstruction technology to process toxic pharmaceutical waste and illegal drugs. Our technology can significantly reduce the volume of waste, but further, the outputs of the technology are chemically inert, and therefore not hazardous to the environment.
Our research will transform the New Zealand pharmaceutical waste disposal system, and represents a complete rethink
of our existing approaches. It will provide the waste sector with the best-in-class technology solution for eliminating toxic pharmaceutical waste at the source.
A clean solution to the greenhouse gases we aren’t yet talking about
It is estimated that the anaesthetic gases released by one hospital annually in New Zealand have a carbon footprint of 500 return plane journeys between New Zealand and London.
The main anaesthetic gases used in New Zealand hospitals are sevoflurane and desflurane, halogenated ethers that are usually administered in a carrier gas comprised of oxygen and nitrous oxide, or a mixture of both. Yet more than 95 percent of anaesthetic gases given to patients are expelled by them, and then into the atmosphere where they contribute to the heating of our planet.
We have developed a way to capture those gases and dispose of them in an environmentally benign way. Our system will reduce emissions in New Zealand by 20,000 tonnes of CO₂ equivalent per annum.
Capturing Smoke – A new high-value food additives from Kānuka and Mānuka
We have developed new high-value food additive products in collaboration and engagement with Māori communities of East Cape (Te Tai Rāwhiti).
Kānuka is an especially extensive resource of underutilised Māori land. While simultaneously providing more employment for these communities, our project also addresses a national challenge of utilising idle Māori land for the economic contribution towards Māori.
The project titled kauruki, develops a new technology to extract maximum value from these Māori indigenous plants. By integrating fast pyrolysis and spray drying processes, we will produce a high quality unique products, mānuka and kānuka liquid smoke and dry smoke powder. When compared to traditional food smoking processes, our process is safer, more energy-efficient and environmentally sustainable. This project will extend our resource recovery and valorisation research to the food and food additive manufacturing areas.
Conversion of pelagic seaweed to biogas and biofertiliser
In recent years pelagic Sargassum has invaded the coastlines of the Caribbean region, Gulf of Mexico, Florida and West Africa, triggering human health concerns and negatively impacting environmental and economic productivity. This macroalgae also shows biofuel potential but hitherto, methane recovery is low due to a carbon to nitrogen ratio below 20:1, the restricted bioavailability of structurally complex carbohydrates for degradation and high insoluble fibre, salt, polyphenol and sulfur content.
Our research aims to the valorisation of these invasive seaweeds into biogas and fertiliser using hydrothermal pretreatment and anaerobic digestion technologies.
Incorporating hydrothermal pretreatment prior to anaerobic digestion increases the degradation and solubilisation of organic components in Sargassum for effective and accelerated methane fermentation downstream. Hydrothermal pretreatment also diminished the concentration of H2S in biogas thus mitigating challenges associated with biodigester performance and harmful odorous emissions.
Thermal hydrolysis and anaerobic co-digestion of municipal sludge and organic waste
Sewage sludge disposal is one of the biggest challenges that Wastewater treatment plants (WWTPs) are facing because of energy cost, environmental pollution, and hazardous contaminants. Anaerobic digestion is commonly used because of its various benefits, such as low environmental impacts, minimum solid residue, and high bioenergy production. However, due to the low hydrolysis rate anaerobic digestion technology has shown several limitations in sewage sludge digestion such as huge volume in design and low rate of biogas production and methane content.
We use thermal hydrolysis (TH) process to enhance AD performance. During TH process, the sterilisation of sludge, the disintegration of sludge flocs, and the rupture of cooked cell membranes occur due to high temperature and pressure conditions. As a consequence, TH process of sewage sludge brings in numerous advantages in terms of sludge pre-treatment, including increasing solubilisation to enhance anaerobic biogas production
Through our research, we are developing a detailed fundamental understanding of the thermal hydrolysis process for anaerobic digestion of sludge and to optimise the process for maximum biogas production. This information plays a central role in the reactor design and process scale-up. These are very important for process development when a sound knowledge and understanding of the reaction mechanism and engineering skills for obtaining a satisfactory performance of the process are required.
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New additives to enhance landfill gas generation from aged waste
Municipal landfills are a viable source of landfill gas (LFG), which can be used to produce heat and electricity. Many landfills suffer from a sharp drop in landfill gas generation after an initial period of gas generation.
We have developed two different additives (neutral red and biochar) were tested and implemented them in the Hampton Downs landfill site. This additive are categorised as direct interspecies electron transfer (DIET) additives, which promote electron transfer between microorganisms without relying on main electron carriers such as hydrogen and formate in the AD process.
Our laboratory and field study results show that LFG-generation quality and quantity can be increased significantly using these novel additives.
Recovery of bioactives using subcritical and supercritical fluid extractions
Subcritical water (SWE) and supercritical carbon dioxide extraction (SCCO2) are novel extraction techniques for recovering compounds with food-enhancement and health-promoting properties, from various plants and biomaterials. These extraction techniques are efficient, economical and promising routes for resource recovery without compromising the quality of the extracted products.
In our research group, we use these techniques, standalone or combined sequentially or with other extraction methods, to selectively extract different bioactive compounds from plant materials, marine resources, and food processing residues.
Biodegradation of plastic waste using naturally occurring microbes
Due to the mass production of plastic and lack of proper plastic waste treatment systems, an energy-efficient, practical, and environmentally friendly approach is required. Biodegradation is a green and attractive method to solve plastic waste problems.
We use different microbial strains from soil, activated sludge, farm sludge, and worms’ excreta using unstimulated (natural occurring) and stimulated approaches to identify promising pure strains. The outcome of this research enlightens the use of microbial strains for plastic biodegradation.
Among different candidates, we have found Penicillium raperi, Aspergillus flavus, Penicillium glaucoroseum, and Pseudomonas sp as the plastic degrading microbes.
Stimulation of strains as a biodegradation approach can reduce the operational cost by shortening the degradation time. From the given results it can be confirmed that the isolated strains were able to degrade non-degradable plastic in both stimulated and unstimulated conditions within the given period.
Busting Waste with Water!
Catalytic hydrothermal deconstruction
We use hot, pressurised water to break down the hazardous organic compounds into safe, inert compounds, mainly water and organic acids such as acetic acid. The process is ‘busting waste with water’.
The high temperature catalytic hydrothermal processing technology has the advantages of being scalable (‘right-sized’), clean (using only water), and low energy input (180-400°C), therefore low operational costs.
The mechanism of catalytic hydrothermal deconstruction involves the formation of hydroxyl free radicals on the catalyst. A series of free radical reactions break down organic waste to aldehydes, ketones, and carboxylic acids. Carboxylic acids in the presence of oxygen, further break down into carbon dioxide and water.
We are developing highly selective metal catalysts by manipulating the active metals in heterogeneous catalysts in order to minimise the leaching of the active metals during the successive operations.
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