TECHNICALLY SPEAKING
Bringing bugs to bear on BNR
A process that enhances biological nutrient removal by allowing specific species of Bacillus to be grown in the
biomass is proving effective in wastewater treatment plants. Frank Rogalla, Mark Jones and Peter Vale report
W
hat to do if the plant does not fit?
The European Commission (EC)
announced last month that it will
take the United Kingdom to the European Court
of Justice on the grounds that the treatment
capacity for the wastewaters collected in London
is in need of improvement. In 2000 the
European Court of Justice judged that the UK
had not identified adequately Nitrogen
Vulnerable Zones, forcing a re-launch of the
designation processes. The Commission alleges
though that the UK, even after its second wave Figure 1: Flow diagram of the HYBACS Process
of designations, has failed to designate many
estuaries and coastal waters as nutrient sensitive, and shows some recent results from two pilot detergent manufacturing and leather finishing.
including major estuaries such as the Thames plants, operated under a closely monitored Industrial enzymes derived from Bacillus
and Humber. programme for at least 12 months. account for over 60% of total global
The upgrade of conventional wastewater production
treatment to nutrient removal is still a major Why Bacillus? ■ To combat and remove deposits in sewers,
challenge, even though in the past 20 years, The key feature of the HYBACS Process is the particularly those containing fat and grease
£2.5B has been spent on improvements in growth of Bacillus in the biomass, which is adept ■ By dosing it into the biomass of wastewater
wastewater treatment in England and Wales. A at producing enzymes. The natural habitat for treatment plants to improve treatment
similar sum is planned for work on combined Bacillus is soil where it forms a large component efficiency, but which tends to last only as long
sewage outlets, such as the £2.6B Thames of the biomass, and degrades and assimilates as the dosing continues
Tunnels project. But as the treatment organic matter deposited by plants and animals
improvements with conventional technologies as part of the natural recycling process. Bacillus Bacillus does not grow in the biomass of
often require more space and energy, companies also accumulates and stores nutrients, particularly conventional wastewater treatment plants, even
are desperate for more innovative solutions. phosphorus, released by the degradation. Certain though the bacteria are generally present in
One option is the new HYBACS Process, a Bacillus species, all of which are heterotrophic, municipal sewage – but only in low
unique wastewater treatment system specifically can also oxidise ammonia and, under anaerobic concentrations. Bacillus spp. survive and
designed to enhance biological nutrient removal and anoxic conditions, denitrify. The biological grow in the HYBACS biomass because it is
(BNR) by growing specific species of Bacillus in functionality of Bacillus is therefore well matched designed to select biologically for these
the biomass. It is well established that Bacillus to the requirements of wastewater treatment. particular bacteria.
spp. can produce a high yield of enzymes capable Cultured Bacillus spp. and their enzymes have
of degrading carbohydrates, proteins and lipids. been used in industry for decades, for example: Process configuration
These enzymes increase overall reaction rates so ■ For the commercial production of enzymes The process, developed in the late 1990s, is
that BNR treatment can be achieved in reactors of used in industries such as food processing, descended from an earlier Bacillus treatment
substantially reduced size, allowing water process called B3, developed a decade earlier.
companies to use HYBACS for upgrading existing The B3 process is an activated sludge (AS)
activated sludge plants on congested sites. process comprising a single biological stage
HYBACS is owned by Bluewater Bio separated into four sequential zones in which the
International (BwB), a firm with offices in pattern of dissolved oxygen (DO) concentration,
London, Prague and South Korea. The process from zone to zone, is controlled to promote
was originally developed in South Korea, where Bacillus growth. As shown in the figure (above),
there are over 20 large scale operational HYBACS also comprises four sequential AS
applications, treating a wide range of wastewaters zones, but these are preceded by a separate first
from municipal sewage to industrial wastewaters biological stage, comprising Shaft Mounted
from abattoir wastewater to landfill leachate. Advanced Reactor Technology (SMART) Units.
Some of the performance results obtained so far While these seem similar in concept to
from operational plants in South Korea are rotating biological contactors, which contain
summarised later in this article. BwB is waffled plates made from solid material, SMART
introducing the technology to new markets, plates are 50mm thick constructed from plastic
currently focusing on Europe and the Middle mesh. The porosity of the mesh is 95%, allowing
East, and this article briefly explains the process Aqualia’s pilot plant at Avila WwTW in Spain the whole plate to fill with active biomass. trianglert
44 Water & Wastewater Treatment November 2009
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