Putting sludge under the microscope

02:39, Oct 14 2014
ESR scientist Jacqui Horswell with a manuka seedling.

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!’’