Wednesday, December 06, 2006

Bauxsol shows viability for phosphate removal

After practical trials, the innovative Bauxsol technology has been shown to offer a viable and economic treatment solution for phosphate removal in municipal and industrial wastewater treatment works.

Following a six-month independent trial by the UK Water Research Council (WRc), the innovative Virotec Bauxsol technology has been shown to offer a viable and economic treatment solution for phosphate removal in municipal and industrial wastewater treatment works. European General Manager at Virotec, Simon Tillotson, said 'We are very excited about the trial outcome. The WRc trial has shown Bauxsol in pellet form to be a viable passive treatment alternative to chemical dosing for phosphorous removal.

Our solution is based on treatment by simply passing wastewaters through the pellets in our Virofilter system, a straightforward process that can operate unattended without the need for control of dosing rates, and all the associated manning, health and safety issues.

It is particularly viable for remote and small-scale sewage treatment works that need a stand alone, reliable and sustainable phosphorous removal process'.

Virotec has developed a range of patented products for removal of phosphate and metals from wastewater streams and groundwater supplies, and for fixing metals in soils and solid wastes.

Simon Tillotson explained, 'Our range of Bauxsol products are produced from the neutralisation and conversion of caustic red mud, a 'waste' product from alumina refining.

We are taking the abundant supply of red mud and turning it into a valuable enhanced product with exceptional contaminant removal properties'.

Bauxsol works by forming strong ionic bonds with phosphate and metal ions in water or soil.

For the metal ions captured, these are immobilised into a non-leachable and non-bioavailable solid residue.

For phosphates, their removal occurs via ionic and precipitation reactions and the phosphates are held in a slow release and bio-available form.

It is estimated that 50 - 80 million metric tons of red mud is produced globally every year.

Virotec recognised the beneficial properties of this resource and developed and patented their ground-breaking neutralisation and conversion process for transforming the red mud into a valuable product.

Simon Tillotson said 'Bauxsol can be applied as a powder or slurry for direct addition to contaminated waters or soils.

It can also be produced in pellet form for use as granular media, or manufactured into larger blocks.

The extremely high porosity of our pelletised product means that on certain applications we can direct the process flow straight through the solid medium'.

The Virotec phosphate removal solution is to install a simple flow-through Virofilter immediately prior to effluent discharge.

This provides a buffering capacity and allows for variations in hydraulic flow and phosphate concentration.

Upstream chemical dosing is not required, and there is the added benefit of reduced sludge production and lower waste disposal costs.

The system easily meets phosphate discharge consents at less than 2 mg/l (as P) and allows trace metal removal and polishing, as well as providing a substrate for promoting biological activity and additional BOD reduction.

The Virofilter can be installed in horizontal or vertical flow beds, or in a trickling filter type arrangement.

For maximum flexibility, beds are installed in a duty and standby configuration with Virofilter streams operating in parallel or in series dependant on the phosphorous removal rate required.

The longevity of Bauxsol in the Virofilter depends on residence time, influent phosphorous concentration and flow rate.

For example, the likely lifetime for an influent of 6 mg/l (as P) is at least 3 years.

The production and use of Bauxsol is a sustainable process creating multiple reusable and recyclable products from an initial environmental problem.

As pellets would still have metal removal capacity following application in phosphate removal, the enriched phosphate pellets could be reused for heavy metal removal such as in acid mine water treatment.

Alternatively, pellets used for iron removal could be reused for phosphate removal.

In the WRc trial, two beds containing Bauxsol pellet media were operated in a horizontal flow reed bed configuration at residence times varying between 4 and 12 hours.

The work demonstrated that up to 85% phosphate removal could be achieved meeting consents of less than 1 or 2 mg/l (as P).

On trial completion the phosphate removal capacity of the Bauxsol media had exceeded 7g P/kg media without any sign that the pellets were close to exhaustion.

However longer term lab-scale trials have demonstrated that Bauxsol can remove at least 12g P/kg.