EC legislation now dictates that all sewage treatment plants have to display effluent quality information on documentation provided with the product.

And, as the legislation tightens regarding effluent discharge, wastewater treatment products manufacturer and designer Balmoral Tanks has introduced a range of small to medium-sized package treatment plants.

The HydroClear is for use in homes or developments housing up to 50 people. It is an aerated biological system, which uses a moving-bed biological reactor (MBBR) at its core.

MBBR technology is a new process in the package wastewater market. It embraces the benefits of common fixed-film media processes without suffering their common downfalls.

Overgrowth of bacteria leading to channelling is an issue with common market process designs such as submerged aerated filters, rotating biological contactors or trickling filter designs.

The MBBR process, widely adopted in larger-scale systems, is incapable of blockage because its media is constantly mobile. The sloughing effect of the media also removes excess growth promoting a continuing regrowth of healthy bacteria, vital to maintaining reliable treatment.

With an eye on the new BS EN 12566-3 European standards, Balmoral, in conjunction with the DTi and Cranfield University’s School of Water Science, designed the new system. It aims to address optimum effluent treatment and other key aspects important to the supply chain including product storage, transport, installation and maintenance.

Phase 1 of the research programme involved an independent 17-week design evaluation programme at Cranfield University based on the procedures set out in BS EN 12566-3. This work allowed the new design to be fully verified in practice before committing the finished product to the CE-accredited test house at PIA in Aachen, Germany.

As WET News went to press, test results showed pollutant removal levels exceeding 97% – 10:15:10mg/l (BOD:Suspended Solids:NH4-N respectively). And this is expected to improve when the final results are received from Aachen later this month.

For the Cranfield tests, a single household model was chosen since the most challenging situations tend to be faced by small systems. A full-size prototype plant was fed with genuine sewage from the university sewage works including washing machine effluent and bath water.

The feed setup was designed to reflect the expected peaks and troughs typical of a single household. Extreme situations were also tested, including no feed, high loadings and power failure, typical of what the plant would face during CE mark European testing.

These tests provide a more rigorous regime with a wider spread of measurements compared with previous approaches and ensure realistic simulations.

The HydroClear represents Balmoral’s third generation of sewage treatment plants. Its predecessor, the continuous aeration plant (CAP), proved popular with trade professionals and end-users alike. But the company’s commitment to providing best-in-class products led to the creation of this solution.

Tim Mackley, wastewater product manager at Balmoral Tanks, says: “The design, performance and shape of the HydroClear offers substantial improvements on what is currently available. European regulations demand higher effluent quality and effective use of new technology was required to achieve this.

“Our successful CAP product was limited to six and 12 population sizes, and we recognised that a broader product range was desirable. The new HydroClear is available in six, 12, 20, 30, 40 and 50 population models.”

He says the company took the design right back to first principles. “A three-year programme of research, design, engineering, testing and production ultimately enabled us to produce a system that far exceeds legislative demands through its reliability of performance.

“The HydroClear offers a build quality the industry has come to expect from Balmoral; a rotationally moulded one-piece high-density polyethylene tank, providing robust on-site characteristics and a ruggedness not found in competitive products.”

The air-blowing compressor is housed in a sealed manway cover – there are no electrics or moving parts within the vessel. Internal servicing is accessed from ground level providing easy, quick and safe maintenance, the company says.

Allan Joyce, managing director of Balmoral Tanks, says: “Although our previous range of wastewater treatment plants was doing extremely well, Balmoral recognised that, to satisfy our clients, particularly installers, modifying the existing product wasn’t really an option.

“They wanted something that was more easily installed, with a low invert depth, while end-users demand high performance, low maintenance and reliability.”

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