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Biowaste science

ESR investigates management and treatment options for the beneficial reuse of wastewater, effluent, greywater, biosolids and sewage sludge. Our focus is holistic, transdisciplinary and culturally responsive approaches based on a carbon-neutral circular economy.

Manuka Environment

Biowaste is any solid or liquid organic, biodegradable waste, including agricultural waste, food waste and greywater. It makes up more than 30% of the total waste going to landfill in Aotearoa New Zealand. ESR looks for innovative and sustainable solutions to minimise, re-use and convert biowaste.

Biowaste circular economy

Building a circular economy for biowaste

When biowaste breaks down it releases harmful greenhouse gases that contribute to four percent of the total greenhouse gas emissions of Aotearoa. Dumping liquid biowaste into waterways also causes problems like algal blooms that pollute water and harm native ecosystems. 

A main driver of our research is to help develop a circular economy for biowaste. We aim to learn about the tikanga and mātauranga Māori relevant to biowaste to inform the design of a circular biowaste management system. Much of this work is led by our Māori partners and we help to co-design an approach that is relevant to and respectful of te ao Māori.

Creating circular economies of biowaste requires a multi-disciplinary approach, because of the mix of social, economic, environmental, infrastructural, political and cultural factors involved. The first step is to reimagine biowaste as a resource, rather than as waste, because there are good options for alternative, economical, and beneficial uses. 

ESR’s biowaste team is working on ways to reuse, instead of lose, the valuable biological and chemical resources biowaste contains. We have expertise in treatment and reuse options for food waste, wastewater, effluent, greywater, biosolids and sewage sludge with a focus on optimizing economic and environmental sustainability and minimizing greenhouse gas emission. For example, properly treated biowaste can become a sustainable addition to soil. It can increase water holding capacity, add beneficial organisms and essential plant nutrients, and reduce the reliance on inorganic fertilisers. It can even be used for energy production, to restore ecosystem functions, and to sustainably extract resources from using insects.

We work with central and local government, regional councils, iwi, communities and stakeholders to build innovative and fit-for-purpose solutions for the sustainable re-use of biowaste and help to develop national guidelines for beneficial applications of organic waste to land. Our community engagement approach helps us to integrate local knowledge and develop solutions that are culturally appropriate and have enduring community support, in addition to being scientifically sound.

Insects to recycle biowaste

Insects to recycle biowaste

The research team is investigating the use of insect larvae of the species Black Soldier Fly to recycle biowaste. Results showed that Black Soldier Fly larvae eat nearly half of biosolids from a wastewater treatment plants in less than 20 days, without accumulating of heavy metals in their bodies. In a case of “kill two birds with one stone,” the larvae can be used to manage biowaste and recover resources that can then be used for other industries. Further research will determine which kind of high-value products can be made from the larvae. The results are key for transitioning to a circular economy where all the waste from wastewater treatment plants is revalued and reused. 

This research was done in collaboration with Brett Robinson at UC and partners at Prescient Nutrition provided the Black Soldier Fly larvae.

In the video below, Environmental Scientist and Microbiologist, Dr Kristin Bohm, describes ESR's Ōhanga Āmiomio/Circular Economy for Biowaste project. She talks about how the team is looking at using natural systems to create sustainable solutions for biowaste, and specifically how black soldier fly larvae can process biowaste into a usable product.

Native ecosystems for biowaste management

Native ecosystems for biowaste management

We investigate how native vegetation and ecosystems can improve water quality and benefit from biowaste. Our research has shown that native species can mitigate water pollution and native plantings can thrive with the application of both biosolids and treated wastewater. We are committed to developing a sustainable approach that can transform both community biowaste and marginal or unproductive land through the planting of native vegetation. We carry out this research in the field and in collaboration with local communities, councils, the University of Canterbury, and Manaaki Whenua/Landcare Research.

Working with colleagues at Lincoln University New Zealand, we have demonstrated that the antimicrobial properties of mānuka and kānuka (usually recorded in honey and essential oils) are also present in root systems. This means that microbial contaminants (measured by E. coli as an indicator) die-off is much faster under mānuka and kānuka than under pasture. Further, mānuka and kānuka have deep root systems which reduces nitrate leaching in comparison to pasture or radiata pine. 

With these results in mind, restoring native vegetation where mānuka and kānuka are included in the margins of waterways, could reduce the amount of nutrients, sediments and pathogens that arrive from farming lands. In the same way, plantations of mānuka and kānuka could be used to safely land-treat biowastes such as municipal wastewater or biosolids. 

ESR is leading projects around Lake Waikare and Lake Wairarapa to demonstrate and quantify the potential of mānuka and kānuka dominated native vegetation, to increase the water quality affected by farming activities. These projects are funded by the Waikato River Authority, Waikato Regional Council, Greater Wellington Regional Council, and ESR Strategic Science Investment Funding, and count on numerous collaborators: Ngā Muka Ltd, Te Riu o Waikato Ltd, Matahuru Marae / Nikau Farm Trust, Ecoquest, Rangitane, Kahungunu ki Wairarapa and Manuka Farms.

Current projects are seeking to find other native plants with similar properties as mānuka and kānuka. As a first step, we are screening a list of potential native plants for their antimicrobial properties. For this, plant extracts of 15 native species from North Island and South Island are being tested against important pathogens such as Staphylococcus aureus, and Campylobacter jejuni. We expect to increase the knowledge about potential native plants for reducing pathogen and nitrogen loads into waterways, as well as to provide incentives for increasing the biodiversity in riparian plantations.