We’ve all seen this. Walking down the street we come across an unsightly, muddy stain tracing down into a stormwater drain; cement waste — slurry — from a building site that’s been hosed out onto the pavement so it washes into the drains.
Sure, it looks bad, but it’s not particularly harmful – right?
But a new product, designed by tradespeople for tradespeople, offers a cost effective and simple ‘best practice’ solution to this pollution.
It’s called SLURRYTUB – a way to “dump your slurry the better way”.
In March, the start-up’s founder, Angus Hudson, spoke during the Ocean Impact Innovation Panel, at the annual Blue Solutions Summit in Sydney.
“I’ve been a builder my whole life, for 40 years in the building industry, and part of that was identifying this problem which was: where do builders wash up their cement-contaminated tools at the end of the day?” Hudson said.
“Builders have a lot on their plate managing a building site, managing the costs and the trades and the client and the architect and everything else, [which] often takes priority. Particularly within the inner city it’s a big problem, because all the surfaces are hard, and you will often see noncompliant acts where people wash up down the drain and hose it away.”
New South Wales Environmental Protection Authority (EPA) Executive Director Regulatory Operations Steve Beaman says slurry is not harmless.
“Many builders and renovators think that sediment and building products going into the stormwater drain won’t have much of an impact. However, the sediment from even a single building site can damage local streams and waterways, and when this action is replicated hundreds of times on building sites across the region, it can have a significant environmental impact,” Beaman told slurrytub.com, commenting on Sydney Council’s Get the Site Right campaign which conducts biannual targeted inspections of building sites.
The total suspended solids (TSS) and heavy metal contaminants in this so-called “wet trade slurry” can leach into and contaminate soil and groundwater. When entering the stormwater system, it can damage drainage infrastructure and the delicate ecosystems and aquatic species in creeks, rivers, and ultimately bays and oceans.
But Hudson has come up with a simple solution that captures 99% of the suspended solids and 90% of heavy metals, so they can be safely disposed of in landfill instead.
How SLURRYTUB works
The Australian-made product consists of a recyclable polypropylene tub and a 100% cellulose, biodegradable filter paper.
SLURRYTUB CEO David Flintoff said that it works much like a coffee filter: “[SLURRYTUB] separates the solids from the wash water down to 25-28 microns, allowing filtered, cleared water to drain or be recycled.”
For context, that’s about the size of a white blood cell.
“The SLURRYTUB filter process captures the suspended solids and reduces the TSS concentration from above 9,000 mg/L to less than 50mg/L. By doing so, the heavy metals like Arsenic, Mercury, Zinc and Lead are also reduced significantly,” he said.
Most of the water should drain within 30-60 minutes, depending on the slurry contents, and the filtered wash water can then be re-used on the job site. SLURRYTUB saves an estimated 54 litres of water per use (based on a ‘typical’ 3 minutes of washing down the job site with a garden hose, at 18 litres per minute).
The recycled water still contains an elevated pH level, as the SLURRYTUB filters alone do not reduce the high alkalinity of cement and concrete wash water. There are commonly available ‘dosing solutions’ that will reduce the pH level to neutral for when that is required.
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