027 | 100
Johanna Johnson
Biochar from human waste 

27 min 15 sec

Johanna Johnson is a former chemist and water management expert who leads sustainable projects at Logan City Council in Queensland, which has pioneered an Australian-first water treatment facility. The Loganholme Wastewater Treatment Plant now uses a gasification process to transform 34,000 tonnes of biosolids (treated and partially dewatered sewage sludge) annually into biochar, a form of sequestered carbon. After a successful trial in 2020, Logan Water is constructing a permanent biosolids gasification facility which will be operational by mid-2022. This will save Logan Water and the community around $500,000 a year in the cost of managing biosolids.

Polymath Nate Byrne is a meteorologist, oceanographer, science communicator and former navy officer, but is perhaps most well-known for his high energy ABC News Breakfast weather broadcasts. From briefing senior military officers and hosting children’s science shows, to presenting the nation’s weather in times of emergency and calm, Byrne understands the importance of engaging and climate-focused communications. He helped launch the University of Melbourne Climate Futures program and maintains a close eye on developing climate stories. While weather is his speciality, Byrne is driven to share narratives about the world and the role of climate change in shaping our future.

Logan City Council in Queensland is transforming human waste into biochar, a process which sequesters carbon, destroys microplastics and saves the community money. Johanna Johnson spearheads the Australian-first project, which will help the Council meet its target of carbon neutral operations in 2022.

We’re basically reducing our carbon content and putting it back into that biochar rather than into the atmosphere.

– Johanna Johnson

We’re actually consuming, and we wouldn’t even know it, about a credit card a month of plastic.

– Johanna Johnson

We’ve just commissioned the first of its kind gasification facility.

– Johanna Johnson

We’re taking out that loop of natural gas that would have been traditionally used for these dryers and creating our own…renewable energy.

– Johanna Johnson

They really shouldn’t be named wastewater treatment plants. They should be looked at as resource recovery.

– Johanna Johnson

I’m hoping that we have our wastewater treatments plants that are totally circular economy principles, so producing its own energy, having sustainable products and really supporting our community.

– Johanna Johnson

We’re basically reducing our carbon content and putting it back into that biochar rather than into the atmosphere.

– Johanna Johnson

Nate Byrne

Welcome to 100 Climate Conversations and thank you so much for joining us. The series presents 100 visionary Australians that are taking positive action to respond to the most critical issue of our time, climate change. We’re recording live today in the Boiler Hall of the Powerhouse museum. Now, before it was home to the museum, it was the Ultimo Power Station. Built in 1899, it supplied coal powered electricity to Sydney’s tram system right into the 1960s. In the context of this architectural artefact, we shift our focus away from coal powered stuff forward to the innovations of the net zero revolution.

I’d like to start by acknowledging the Traditional Custodians of the ancestral homelands upon which we meet today, the Gadigal people of the Eora Nation. We respect their Elders past and present, and recognise their continuous connection to Country, never ceded. My name is Nate Byrne and I’m thrilled to be hosting 100 Climate Conversations throughout the Sydney Science Festival. The lovely person sitting next to me is Johanna Johnson, who is a former chemist, and the current Sustainable Solutions Llead at Logan Water in Queensland, who is leading a Wworld Ffirst water treatment process, turning human waste into energy and agricultural products. We are so thrilled to have her joining us today. Please help me welcome Johanna.

Jo, I can’t imagine many kids who would say to their mum, ‘I really want to fix dirty water.’ What did you want to be when you grew up?

Johanna Johnson

I suppose when I was in high school, I was more around the histories and the sciences, loved it. But I was aiming to be a pharmacist.

NB

What led you to that?

JJ

I love the chemistry and that’s really where it was at, finding and curious about different things and the whole idea of, I suppose, looking at different types of drugs and the research out of it. Loved it. Yeah, I did three years of pharmacy and then realised I absolutely loved the water industry.

NB

So where in the pharmacy side of things did the water kind of come in?

JJ

So, I started off in the Logan Water Lab just as doing some research around things like drugs and pharmaceuticals that were going into sewage treatment plants, realised I really loved the water industry and switched careers. So, it was really looking at I suppose then things like emerging contaminants of concern were things that I absolutely loved learning about and looking at ways to fix it.

NB

So, we’ve been treating water for a long time. How do we fix those contaminants, in the traditional way?

JJ

All of our sewage goes into wastewater treatment plants. Those wastewater treatment plants have oxidation processes and it’s really looking at those microbes dealing with I suppose the sludge portion of it, as well as the water side of it as well. So, it goes through chlorination, dechlorination, all those types of things to basically treat so that you have a solid stream, which is your biosolids, and then you have your water stream, which is, would then be, either environmental flow into the river, but that’s after significant treatment through our wastewater treatment plant.

NB

What happens with the solid stuff?

JJ

So traditionally, most sewage treatment plants either have things like centrifuges. It goes into a filter press which squidgies the solids and gets it to only about 86 per cent water, 14 per cent dryies, is what we classify it as. So, that biosolids is basically treated so that it’s, we’re transporting water when we’re transporting biosolids, and then that will be disposed of at land.

NB

So landfill, essentially?

JJ

So, it can go to landfill. and At Loganholme it goes to agricultural land and the Darling Downs, so about 300 kilometres away.

NB

Okay. So, it’s already useful for agriculture?

JJ

Yes. But in a wastewater treatment plant process, it’s costing around 1.8 million arising just – and that’s for a medium-sized wastewater treatment plant – to dispose of that and it’s about 30 per cent of our operating costs.

NB

And most of what you’re transporting is just water. Why don’t you recover more of that water before it’s sent out?

JJ

So, the issue with recovering water is the more you recover, the more energy intensive it is. So, lots of places will have belt filter presses or centrifuge and the centrifuge will get it to about maybe 22, 23 per cent dry. But the more water you take out, the more energy intensive it is, and it just, it’s not cost benefit or it’s actually worse for the environment.

NB

What are the downsides of the way that we are traditionally treating our sewage?

JJ

There’s still things of concern that are in our sewage sludge. So, when we’re analysing the Loganholme treatment plant, we found glitter poop, so.

NB

Oh, well, okay, okay, what on Eearth is glitter poop?

JJ

So, basically things like microplastics and glitter will go through a sewage treatment plant and end up in your solid streams. So basically, enmeshed in your biosolids is things that are microplastics. So, you get them from activewear, when you’re washing activewear, it goes into your sewage pipes. Things like glitter from cosmetics and all that type of stuff all ends up in biosolids.

NB

So, those microplastics that they’re, that’s something you can’t remove in the process?

We’re actually consuming, and we wouldn’t even know it, about a credit card a month of plastic.

– Johanna Johnson

JJ

No. So, not just from biosolids, but we’re actually consuming, and we wouldn’t even know it, about a credit card a month in plastics. Yes.

NB

Let’s, let’s walk back on that a second. Consuming a credit card’s worth a month.

JJ

So Teflon and all those types of things using plastic utensils, plastic plates, all of that. Some of them will be actually going into you rather than staying on the plate., eEven in the UK, you’re seeing them going into the terrestrial systems and things like meat products and all those types of things there will be forms of I suppose microplastics and that as well, so that’s how we’re consuming them as well.

NB

So, that’s a bit about traditional ways of dealing with things. You’re not satisfied with that at Logan City. So, tell me, what have you done and what is it that you are doing differently?

JJ

We’re kind of looking at the whole of processes and we’re looking at all of our waste streams and what we can do to make products or go back into that circular economy kind of side of it. But right now, we’ve just commissioned the first of its kind gasification facility. What that is, is instead of having our belt filter press and dealing with and making biosolids, we’re going through a gasifier and there’s lots of things up into the gasifier, gasifier and making biochar. To go through the gasifier though, we need to get to 90 per cent dry, so that was always the issue with biosolids. How do we make it dry enough to go through something like this process and without causing, I suppose, environmental harm.

How we’re doing that is going through centrifuges and it’s getting 23 per cent dry and then it’s going through a dryer, and this dryer is 18 metres long and two belts and that gets it to 90 per cent dry. The 90 per cent dry biosolids will then go to the gasifier. The reason we can do this process is a gasifier produces a biogas, and that biogas is then transferred as heat energy back to the dryers to dry the biosolids. So, we’re taking out that loop of natural gas that would have been traditionally used for these dryers and creating our own, so that own renewable energy and that really cuts down A: the costs, but also, I suppose, the use of natural gas as well.

NB

What is biochar?

JJ

Brought some with me, this is biochar.

NB

That’s formerly poo?

JJ

Yes, this is biochar made from pure biosolids. If I open this up and it was biosolids, everyone in this theater would be running away because the smell and just the –, you wouldn’t want to open this jar. Whereas, yes, I can open this jar and move it around and you wouldn’t even know that it was biosolids.

NB

Can I have a look?

We’ve just commissioned the first of its kind gasification facility.

– Johanna Johnson

JJ

Yes, you can.

NB

Oh, wow. It’s sort of, kind of earthy. It just smells a bit like sort of what you’d get from Bunnings when you have a potting mix.

JJ

Yeah.

NB

Can I touch it?

JJ

Yeah, go for it.

NB

Does it feel ever so slightly moist?

JJ

We have to quench it a little bit after it goes through the gasifier. So, because it’s heated at 650 degrees, we don’t want it to keep charring out, so we quench it. The cool thing about biochar in general is that it holds your water content, and it has, it still keeps your phosphorus and your potassium, so really great for agricultural use, especially in Australia because we’re very arid, you want to keep that water content back in the soil. That’s what biochar does, compared to its traditional biosolids from.

NB

Sweet. Because it’s been heat treated, I assume this is completely safe to touch?

JJ

Most definitely. It doesn’t have any of the nasty viruses that you would get in things that you would talk about with biosolids. And it’s just storing destroying things like your microplastics and PFAS’s and all those chemicals that you’d get through emerging contaminants.

NB

PFAS for the uninitiated?

We’re taking out that loop of natural gas that would have been traditionally used for these dryers and creating our own…renewable energy.

– Johanna Johnson

JJ

Perfluoroalkyl substances. So, they’re basically really emerging contaminants of concern, people would know about them from firefighting foam and those sort of things. They stay in and basically, they’re called ‘forever chemicals’ because they just don’t destruct like in a natural way of cycle. So, they’re very nasty product –, very useful, so Scotchgard and all those types of things, you’d find them in that because it’s got hydrophilic and hydrophobic properties, which means that basically stain resistant, water resistant, so that’s why people like them for those types of products. [They’re] really bad for human health because they’re persistent organic pollutants. They stay in your body system, they just will not come out and they can have nasty health effects as well. Really hard to destroy in a natural cycle, so gasification actually thermally treats it.

NB

What actually is physically in that biochar?

JJ

That’s sequestered carbon. What that means is instead of going, in a normal process if you applied biosolids to land, it mineralises, so that’s methane back into the environment, not the greatest as carbon emissions go. When it goes through a gasifier, it sequesters the carbon, which means it locks it up and it won’t go back in, so it’s fixed carbon content that will stay back into the agricultural soil, which is where you want it.

It has also other great products for the ag sector. So, it’s got potassium, phosphorus, zinc, copper, all the things that you need for plant growth, really high end. So, the agricultural sector is very excited about this, these types of products. And yeah, we’re looking at different, I suppose other ways of using it as well. So activated carbon would be another form that we could possibly use there, so we’re looking at that. What this could be used in? oOdor, so odor control, lots of filters would have and we use it in our wastewater treatment plants. So, it’s another way of, I suppose, coming back to that circular economy of using it ourselves as well as looking at the wider market as well.

NB

So you end up, at the end of the day, if you’re sending this out somewhere, those microplastics no longer an issue?

JJ

So, in our demonstration plan and we’re just proving this out at the moment, was a 64 per cent reduction, but it doesn’t go back into the terrestrial cycle, so it stays in the carbon, so it doesn’t go back into the basic agricultural system. Whereas and PFAS is, you would find PFAS in biosolids in low concentrations, it’s non-detectable in biochar.

NB

So, we end up, you’ve heated up this dried solid mass, you’re ending up with biochar and the rest that’s coming off. What is that?

JJ

So that’s it goes through your oxidiser first, that’s set at 850 degrees. So, that deals with all of your volatile compounds and PFAS and all those types of things. It then goes through a wet scrubber which takes out your SOx, your NOx, so sulfurs and your nitrous oxides and all those sorts types of things are dealt with in the wet scrubber and particulates, because we don’t want particulates going back into the atmosphere either. aAnd then it goes to a wet ESP, which is an electrostatic precipitator. It has a rainfall basically, in this massive tank shot with electricity and what we call cations and anions basically drop your particulates to the ground. And so, then that goes back and all of this, these waste products, are recycled back into the wastewater treatment plant and goes back through their process, so that we’re not putting them through the stack that goes into the environment.

What goes through the stack at the end is highly controlled because we’re on what is an environmental authority, at the wastewater treatment plant, so we have guidelines that we can’t go over. So, we monitor things like carbon monoxide, oxygen, your nitrous oxides, your SOx and those types of things through an emissions control system, so we know exactly what’s coming through the stack. How that works is that we’re basically reducing our carbon content and putting it back into that biochar rather than into the atmosphere.

NB

So, we’re ending up with this really, really interesting and useful substance, biochar and you’re saying, there’s zinc and phosphorus and all of that. Does what you’re putting in radically affect what you’re getting out at the end?

JJ

When we’re talking about our traditional process of biosolids, that was about 34,000 tons of biosolids that was produced. And again, most of that is water that we’re transporting. Biochar it’s about 3000 tons. So, it significantly reduces the volume that we produce. And it also then goes through and is able to be applied to land so we’vre got less truck movements, less, a better, its higher carbon content, it doesn’t have any of the chemicals that we would have been worried about being applied long term to land. So, all of that is incorporated and then biochar.

NB

So a big part of the process here is you’re sequestering that carbon. Where would it have otherwise gone?

JJ

Into the atmosphere. So, all up, the carbon that’s sequestered is around 6000 tons per annum, for our wastewater treatment plant. If this was on scale, every wastewater treatment plant, that would be a humungous number because we’re only dealing with about 45 megalitres per day of sewage. But there is quite a significant amount of wastewater treatment plants that we have and if that was on the scale, it would be an astronomical amount.

NB

Is this I meansomething, could you take one of the major city centres, highly, densely populated places, and still treat their sewage in the same way?

JJ

Massively so, because it’s great for scale. So, you’re creating all of your internal energy, all that type of stuff. Biosolids management in general does need to have quite a lot of land space. So, all of our sewage treatment plants do have the land, that land capability., pPlus you’re reducing your volumes off of truck movements and all that kind of side of it. And so yes, we’ve actually been talking to a lot of the water utilities, every week we’re having visitors come through from other water utilities to look at how they can actually implement into their biosolids management strategy because the risks are there and just going to be increasing with fuel costs and all those types of things.

NB

So, who is it that wants to get their hands on this biochar? So, you said it’s good for agriculture. I’m assuming we’re just like sprinkling it on fields, sort of thing. Who else, though, is keen on it?

JJ

So, we have had lots of interest from composters, concreting, brick manufacturing, all those types of things that would need like an ash. What this does is that sequestered carbon is needed, and it would significantly reduce concrete and bricks and those high- intensive carbon products to be low carbon and really, really great for the environment. So, even things like bitumen and roads, you could use it on that. We’re sort of investigating at the moment, it’s so new, we had to do a lot of testing to make sure this is safe and applicable. So, we’re also looking at things like activated carbon with universities as well. But yes, agriculturals, the way that we’re looking at going, because it fits under what we call the end-of-waste code for biosolids. So, we’re highly regulated and so there’s certain things that we can use it for. So, agriculture is the easiest and we’re looking at setting up an end-of-waste code for biochar in Queensland, which will then open up the market so that other areas can start using the product.

NB

All right. You’ve mentioned the market there. Is this a money maker?

JJ

Well, we pay at the moment for disposing of our biosolids. We’re looking at actually getting revenue back for the sale of our biochar. So, it’s definitely changing the way we’re viewing waste streams within our wastewater treatment plants. They really shouldn’t be named wastewater treatment plants, they should be looked at as resource recovery and really going at all of our waste streams, how we make products out of that and really achieve a circular economy.

NB

I imagine that when you first say to council, to government, people probably are a little bit resistant. Did you find that to be the case?

They really shouldn’t be named wastewater treatment plants. They should be looked at as resource recovery.

– Johanna Johnson

JJ

Logan City Council is probably ahead of the curve in that regard. We’ve got to be carbon neutral by the end of the year, as a council. So, that includes all the wastewater treatment plants, landfill all that. And so that’s been a key driver for the past five years, end of this year we will be carbon neutral. So, a lot of these projects we’ve actually been able to get a leg up because we’re saying, ‘We’re going to be reducing our carbon and we’re looking at truck movements, we’re looking at all these types of things.’ Moving into renewables and looking at the waste streams is encouraged because we can see that as a community, we’re going to be significantly impacted by things like urban heat development, all that type of stuff. If we don’t do something now, we’re going to be dealing the consequences later. And that’s just not acceptable.

NB

How long does it take to recover the initial input costs? But you’re potentially able to, I guess, sell this biochar? Is this something that’s like a no-brainer investment?

JJ

We were able to get a significant grant opportunity for the original project from the Australian Renewable Energy Agency, so 6.23 million because we are a council, we are a water industry, very risk adverse when it comes to these types of things. But on a business case, when you’re looking at the rising costs, we were paying 1.8 million per year minimum, that would actually be rising this year to about 2.2. We’re going from 2.2 down to about 500,000 just in operational costs. So, it is actually a cost benefit and if we sell, that’s even greater. So, we’re actually looking at having a revenue stream rather than costing us 500,000. What that means is, yes, it is cost benefit for all, for utilities to go down this process and I suppose all of the water utilities are looking at us to see where we hit, so that they can follow suit and bring up the business cases.

NB

How close are you to being carbon neutral now?

JJ

So, these types of projects, so this gasification does about 6000 tons per annum, but that will only increase because we’re looking at diverting all of our wastewater treatment plants to Loganholme to go through the process. We’ve put in solar farms, so about 1.1 megawatts of solar is currently at the treatment plant and we’re looking at how to actually increase that so that it’s off the grid. So, when you’re looking at energy for the waste side of it, we’re about 40 per cent of the energy usage for the whole council. So, we’re looking at things of increasing solar as well, so that basically we can be our own renewable energy kind of factor. All up we will be hopefully implementing and we’re doing feasibility studies of different waste streams, so things like hydrogen, solar, you name it, we’re looking at it, so that we can be basically self-sufficient.

NB

Is there a future where you’re carbon negative?

JJ

Most definitely. Because that’s the only way to really look at this. If we’ve got all these products, if we don’t go, if we do the circular economy and circular economy right, we should be carbon negative.

NB

How long between now and that future where you might be fighting climate change not only, not contributing, but helping to pull back from the climate crisis?

JJ

I would hope that we are there in the next five to ten years. Purely because there’s a strong push, we will be carbon neutral by the end of the year. How do we get there for the future? The only way forward is to look at innovation and look at where technology is going.

NB

Is there something special about Logan or is this exportable? Can this go anywhere? And who else in the world is already doing this kind of stuff?

JJ

So, this gasification process, we think is probably the first of its kind on purely biosolids. But yes, it’s totally exportable. We have been getting massive interest from overseas. We we’re just up for an international award at the International Water Association because it’s so innovative and they’re really trying to push the targets out there.

So, things like the UK and Europe in general, they’ve got very strict carbon emissions kind of guidelines, so when they’re seeing somewhere like Logan and it’s quite a small council saying, ‘We have actually got a solution for biosolids management, it does take notice. We’ll be having delegates from all over the world coming, so I think we’re looking at groups coming from Indonesia, so you name it there’re lots of people looking at it and we are supplying that information and very open with information as to how we can achieve biosolids management.

NB

Does this have to apply to water waste sewage stuff? Could it also be used to help other waste streams where you don’t maybe have to remove the water first?

JJ

Most definitely. So, things like FOGO, so Food Organics, Green Organics, we’re sort of looking at that at the moment and where that would sit because again, that’s a massive component of what we put into landfill, right? aAnd as a council we do have landfill. So, we’re looking at, when I’m saying, we’re looking at waste streams for all of Logan water and wastewater treatment plants that’s actually broadened out. So, things like FOGO would be amazing if we could do that, it still has a high-water content though. So, all of our food has water content in it. So, how do we deal with that will be the crux of the problem. So, can we deal with it like we do with biosolids? Most definitely could.

So, it’s things like – and I get all science and nerdy and talk about calorific value, which is what I love. So, biosolids have a really high calorific value because it’s the same as what we would classify brown coal. Food organics doesn’t have as high a calorific value, so we might have to be supplementing or mixing it with different waste streams to produce the right blend because at the moment, the data that we’re getting back is around 14 megajoules per kilogram. To give context, our biosolids is around 17 to 18, if not 19, so how do we get that so that the heat balance is right, and we can implement the same sort of process? I mean, that would be absolutely amazing if we could, and I think it can be done. But that’s a type of I suppose feasibility and things that we have to look at for future to say, yes, we have this one waste stream but how can we look at that different?

NB

So, there’s a possibility here, in a perfect world where you’re taking several waste streams, mixing up your perfect recipes and creating, not only biochar, but perhaps, is there a world where biogas could be drawn off and used beyond just the treatment plant itself? Is biogas a useful product outside of the waste treatment?

I’m hoping that we have our wastewater treatments plants that are totally circular economy principles, so producing its own energy, having sustainable products and really supporting our community.

– Johanna Johnson

JJ

So, when we were talking about wastewater treatment plants, there’s already a process that we use as anaerobic digestion. We don’t have any in Logan, but that takes out and produces electrical energy, already. The reason we wouldn’t do this with gasification is because it lowers your calorific value of your biosolids. So, then you wouldn’t be able to get the heat energy put back, but you are still producing energy from the source. We could, in theory, mix the different processes and we’re not necessarily saying gasification is the only way to go.

There are multiple ways of dealing of this, it’s just looking at which is the appropriate technology for our wastewater treatment plants, for our landfill, for all those types of things, and saying, ‘The technology is there’, but we just need to figure out what the one is going to be, I suppose, able to deal with the issues and have a sustainable product at the end too, because you don’t want to be dealing with a mountain of biochar that you can’t get rid of or that type of stuff. I suppose it’s looking at it from a holistic perspective as well.

NB

I’m so blown away by this. As it stands right now, what does the future look like for you?

JJ

I’m hoping that we have our wastewater treatment plants that are totally circular economy principles, so producing its own energy, having sustainable products and really supporting our community.

NB

Johanna, thank you so much for joining us and talking us through this just revolutionary way of looking at the stuff that, to be frank, that we flush. Please join me in a round of applause. Thank you so much Jo. To follow the program online, you can subscribe wherever you get your podcasts. You can also visit the 100 Climate Conversations exhibition or join us for a live recording like this one. You can go to 100climateconversations.com and just search for 100 Climate Conversations in your pod catcher of choice.

This is a significant new project for the museum and the records of these conversations will form a new climate change archive preserved for future generations in the Powerhouse collection of over 500,000 objects that tell the stories of our time. It is particularly important to First Nations peoples to preserve conversations like this, building on the oral histories and traditions of passing down our knowledges, sciences and innovations which we know allowed our Countries to thrive for tens of thousands of years.

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