Pollutants in watercourses

The active ingredients in many legacy herbicides and pesticides were intended to modify the physiology of the infestation they were designed to control. As a result, they are not naturally biodegradable and so can stay in the ground for many years. Through infiltration, they eventually appear as pesticides in groundwater and in the leachate (the water from rainfall that percolates through the soil, gradually and slowly leaching out the organics as it does so.)

Actively managed fields will inevitably aid this gradual run-off and in time the unwanted recalcitrant compounds will find their way into larger water courses and thence rivers. It’s important this is minimised, as the problem of pollution with these recalcitrant compounds becomes a far larger one when it’s spread further and starts to affect marine life.

The problem of removing agrochemicals from water

Conventional removal techniques like physical filtration, chemical dosing or radiation (like ultraviolet/ozone) are quite often ineffective when dealing with organics of this type; these conventional COD-improving methods – used to reduce the concentrations of other unwanted chemicals in wastewater –  normally require assistance using advanced tertiary treatment technologies.

1. The problem with activated carbon

GAC (granular activated carbon) is one well-known method of effectively treating wastewater to remove organics, but it has several disadvantages:

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First, although GAC offers a massive surface area onto which the organics can be adsorbed, it will lose its effectiveness in time as the carbon will become saturated and will need to be replenished. Just how quickly that needs to happen depends on water throughflow and the type of organic compound being targeted. In many cases, the spent GAC material cannot be recycled so it has to be incinerated. Either way, this impacts on a company’s carbon footprint.

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Second, all activated carbon systems need regular maintenance and must have their throughput carefully controlled otherwise they can suffer from over-limit outputs potentially leading to higher discharge fees or even prosecutions. This can often be attributed to ‘channelling’ – water finding the path of least resistance through a filtration system and not enough organics being adsorbed as a result.

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Last, the constant renewal and replacement of activated carbon filters can be disruptive to a production process and is expensive, both in terms of OpEx and carbon footprint.

Using Nyex for agrochemical reduction from water

The revolutionary Nyex Rosalox™ system from Arvia Technologies merges the most effective elements of adsorption and oxidation to create a unique new patented water treatment system that is efficient, effective and energy-conscious – all at the same time.

Either as a standalone plant or in parallel with legacy installations, an Avia Nyex Rosalox™ reactor system can effectively treat water carrying high levels of recalcitrant compounds and in many cases reduce these to below detectable levels – literally, parts per trillion – far more effectively than any equivalent system.

Why use Nyex™ in remote municipal treatment facilities?

If you have a problem with recalcitrant organics like agrochemicals in remote locations, our Nyex Rosalox™ systems offer many advantages over competing water treatments:

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Combination of adsorption and oxidation technologies means reduced energy use.

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The electric current applied also acts to regenerate the surface of our Nyex™ media, meaning minimal replenishment is needed – normally only 1 – 2% p.a.

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With no moving parts and simple operation, can be operated remotely.

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No chemical dosing to manage.

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No sludge to deal with as all pollutants are converted to water and gas, which is vented.

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Arvia’s systems require minimal maintenance and therefore are ideal for remote applications.

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Compared to other technologies, a Nyex™-based system will last longer and have lower OpEx costs than most other legacy systems.

Case Study: Pesticide removal from reservoir

In one recent trial, Arvia tested water from a raw water reservoir on the island of Jersey. For many years, one of the island’s mainstays of agriculture has been the production of Jersey New Potatoes.

Historically, Oxadixyl had been used locally to control potato blight, but it stopped being applied about 20 years ago.

However, concentrations of Oxadixyl had been found in the reservoir water at around five times over the regulatory limit of 0.1μg/l. In tests, we showed that the installation of a Nyex™ system would reduce concentrations to below regulatory limits in one pass through our systems.

Bear in mind also the tests were carried out using previous-generation Nyex™ technology. Our new generation Nyex Rosalox™ systems are smaller, more energy-efficient and more effective.

For more info on another recent case study in agriculture, check this page out.