Putting sludge under the microscope
Talking at the dinner table about sewage sludge, contaminants and household waste might put a lot of people off their food, but not Jacqui Horswell.
The mother of two is an environmental microbiologist who is constantly doing research into the waste society produces, how it affects the environment, and ways to sustainably manage it.
‘‘Most of the waste society produces goes into landfill. We produce 700,000 tonnes of organic waste, things like green waste, sewage sludge and kitchen waste, and 62 per cent of that goes into landfill,’’ Horswell says.
‘‘Everybody knows how landfills are not particularly good for the environment, so it seems sensible to try to reuse/recycle more of our organic waste.
‘‘That’s what the research programme aims to do, try to divert more of that waste, which aligns with the Government’s waste management strategies.’’ It’s a topic the English-born woman finds fascinating and she admits she could talk it at length about with anyone but she also knows some people find it off-putting.
‘‘When you’re at a dinner party, for instance, nobody is interested in talking about sewage sludge,’’ she says, laughing.
‘‘They’ll say ‘what do you do’, I tell them I’m a researcher; they’ll say ‘oh that’s really interesting and what do you work on’, I’ll tell them I work on sewage sludge and then they kind of drift away.
‘‘Yet I’m always quite happy to bring up the subject at any time, and I must point out that I’ll never be out of a job,’’ she quips.
She works a the Institute of Environmental Science and Research and heads the Centre for Integrated Biowaste Research (CIBR). With funding from the Ministry of Business, Innovation and Employment, she has a hand in various projects that come under CIBR.
One of these is the Greywater Schools project, a joint effort between Porirua’s Corinna School and ESR whereby students are working out if it’s safe to re-use greywater.
Greywater is wastewater from laundries and bathrooms, excluding toilets, and can account for up to three-quarters of wastewater going down the drain from houses.
‘‘While it makes sense to reuse greywater to water lawns and gardens, especially when there is a drought, the students will endeavour to find out how safe it is to reuse as it can contain bacteria and viruses that could make you sick,’’ she says.
Like the work with Corinna School, other areas of Jacqui’s work focus on helping people to better understand and reduce waste that goes down the drain.
To achieve that she works with numerous district and regional councils on the Resource Management Act and key issues and local communities on providing them with science knowledge in order to make good decisions.
‘‘We’ve gone into a community in Kaikoura which has 1500 tonnes of sewage sludge sitting there. It can’t just sit there so they’ve asked us what’s in the sludge and what the consequences would be if they put it on to the land. We go away and research what’s in it and go back to them with their options.
‘‘In sludge, because it’s human waste, there will be pathogens but also a whole range of what we call emerging contaminants, some of those long chemical names you find on your shampoo bottle, some of them are good and some of them are not so good.
‘‘Or for instance, you can buy a toothpaste that contains triclosan, an antimicrobial chemical we really don’t need.
‘‘Now Colgate does a toothpaste with it in and one without yet they cost roughly the same, people don’t realise what triclosan does, it’s the same with liquid soap versus a bar of soap.
‘‘Liquid soap contains antimicrobials, stuff that stops bugs growing in it because it’s liquid, but those chemicals are just not the best for the environment, and a bar of soap works just as well.
‘‘It’s not all about spending a lot of money on eco-products, it’s thinking about what goes down the drain and what contaminants are in that waste because of the products we buy.’’
In the past few years, Horswell’s research has been more along the lines of the effects these contaminants might have on the environment, and developing national guidelines as a result.
‘‘If you want to put sewage sludge on land, for example, it has to have x, y, and z contaminants and no higher than that – we try to put the science behind those numbers but it’s always a moving goalpost because we’ll discover a new chemical, then we’ll do research on whether it’s safe ecologically, and human health wise.’’
While she still enjoys getting out in the field, after 16 years at ESR, the past five as science leader, much of her job is now desk-based.
That means managing a team of scientists from within the programme’s four key partners – Landcare Research, Scion, Cawthron Institute and ESR – developing strategies, financial reporting and, most importantly, securing funding.
In fact, winning the last funding bid four years ago was a highlight for Horswell, who had just taken over the programme at the time.
‘‘That was a huge responsibility, our jobs depended on it, it was very competitive so I was really proud that we won that money again.’’ Because funding is so hard to come by, Horswell considers herself fortunate in having her very own research programme.
‘‘I know I am extremely lucky and, though I do tend to do the boring financial reporting stuff, what I love the most is working with an eclectic group of scientists from an interesting mix of disciplines.
‘‘ESR has got forensics, all the public health stuff we do as well, the radiation laboratory, then biomedical science. We’re a group of people who wouldn’t normally be put together and that’s where a lot of the cutting-edge science comes from,’’ she says.
Ironically, Horswell doesn’t recall ever making a conscious decision to become a scientist, it was simply a subject she excelled at and enjoyed at school. Having completed a biology degree from Bath University then a PhD in microbiology from Aberdeen University, she moved to New Zealand to take up her first job as a microbiologist at ESR 16 years ago.
‘‘I met my boss Dr Tom Speir when he visited the UK during my PhD. It turned out ESR had small funding pools to allow them to do something new and exciting and bring on board someone new, and that was me.’’
She started out looking into human waste containing pathogens and best-management practice, and has since delivered relevant research on the safety of putting sewage on land through engagement with both the waste and land management sectors.
‘‘We’d identify what the issues were, what the consequences might be and make recommendations but, in my early days, those calls from councils about resource consents were quite scary, knowing my decisions would have consequences.
‘‘But then it’s also really great because you can see your science being used which is fantastic for a scientist.’’
She has since climbed the ranks from scientist to senior scientist to her current role as science leader and, even after almost two decades at ESR, she says she’s still as passionate about her job as she was on day one.
‘‘I don’t notice the time – I look at my watch and it’s midday and I wonder how that happened, but I like that, I like not noticing the time and being so engrossed in my work that suddenly days have gone by.
‘‘I think that’s what happened to the 16 years to be honest!’’