Wastewater Sludge is an Asset
It contains nutrients, energy and precious metals, our ITWP helps you recover them.

Most people rarely think about the wastewater produced daily from their showers, baths, sinks, dishwashers, waste disposals and toilets. We believe this water can be converted from waste to energy to become a valuable resource.

The average New Zealand family uses 250-300 litres of water per person per day to flush toilets, shower and do laundry or the dishes. This figure can easily double if outdoor uses, such as watering lawns, washing the boat or car, rinsing dive gear or filling swimming pools are included.

Most of the water we use becomes wastewater; this wastewater is treated for pathogens before being discharged into nature, oceans, land, or landfills. And that treatment uses a lot of energy. According to my latest rates notice from the Hamiton City Council, it makes up a large portion of our annual costs.

Our wastewater technology is focused on recovering value from the resources contained in wastewater. This process can be complicated because wastewater contains many different types of contaminants. So over the past few years, we explored many ways to make valuable products from wastewater sludge and found that we could reduce all pathogens from the process and convert the wastewater into energy and nutrients.

Now we're trying to educate wastewater engineers, mayors and the public to help kiwis understand the value of wastewater. The idea is to view it as an asset rather than a waste because the wastewater treatment plant can be a water resource recovery facility.

The reality is that wastewater can contain more than three times the amount of energy needed to treat the wastewater plant. So we use a technique for recovering part of this energy is anaerobic digestion (AD). AD is a natural process in which microorganisms feed on grease and other organic materials in wastewater and produce biogas. As Kiwi's, we're familiar with this process; think of it as similar to when yeast can eat up barley to crate our favourite craft beer.

Biogas contains roughly methane, which can be used as a renewable fuel for boilers for dairy plants, heating systems, or turning turbines to generate electricity.

We use a technique called hydrothermal processes that takes sewage sludge, that is, the solids removed from wastewater during treatment – and converts it into biofuel that can replace petrol and natural gas has that is usually extracted from the ground.

We can also extract nutrients from wastewater because it contains nutrients like nitrogen and phosphorus, which are essential elements that plants need to grow.

In wastewater treatment processes, we use energy to convert ammonia from wastewater, mainly from urine, into methane gas. However, industries typically use large quantities of natural gas to convert nitrogen gas back into ammonia, predominantly for producing fertiliser. Can you see why we're dumbfounded that we're not treating waste as valuable?

It would be much more efficient to extract the ammonia from wastewater without converting it directly. Then the collected wastewater sludge could be used as fertiliser. After sanitising it to remove pathogens using a bioorganic process that involves vermicomposting, we can create phosphorus and potassium that farmers can use to reduce the nitrates they use on soil.

Overseas researchers have tested these processes on crops in laboratories and achieved yields comparable to commercial fertilisers, a process we aim to replicate with a SCION in New Zealand.

Wastewater is valuable, and the sooner we start treating it at such tp sooner we can cap the spending on regional wastewater systems by reselling the value created from the energy and nutrients. For example, the water contained metals valued at millions of dollars per year.

These metals are toxic to aquatic life, so they need to be removed. Unfortunately, conventional removal technologies require a lot of energy and produce poisonous sludge, which is sent to landfills costing even more in transport and landfill fees and emissions liability.

With innovative techniques, wastewater our local councils can offer us much more. We hope your local council begins to see a day when there is no "wastewater," just "used water", with a conversion process to create value that reduces your water rates bill.

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Harmaan Madon speaks about his aims for water security and climate change.