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WATER & WASTE TREATMENT


• Crops are 100% GMO-free • Animals are fed on locally grown feed


produced without glyphosate • No imported palm oil or soyabean derived


material • Milk is supplied in returnable glass bottles • Waste heat from production is used in a


district heating scheme, providing enough energy for up to 640 households • Electricity produced by photovoltaic cells


is a further contribution to the Tirol Milch sustainability ethos 2,100m3


The floating sludge was causing poor quality treated water and odour problems


SUSTAINABLE SOLUTION TO SLUDGE BULKING


Ben Hazard, Te-Tech Process Solutions, discusses an alternative solution to tackle sludge bulking while also limiting the use of flocculating chemicals


be easily treated by aerobic biological processes like trickling filters, activated sludge or moving bed biological reactors (MBBRs). Whilst the treatment process is very efficient at meeting BOD consents, there are times when poor sludge settling causes problems with suspended solids. This phenomenon, called “sludge bulking” is


W


due to the proliferation of filamentous bacteria like Microthrix, Trichococcus, Gordonia and Thiothrix. Under normal conditions the growth rate of filamentous bacteria is lower than that of floc forming bacteria, and their presence helps to stick flocs together to produce readily settleable flocs. However, under adverse conditions – low substrate concentration, poor aeration or nutrient deficiency – the high surface area to volume ratio of the filamentous bacteria gives them a feeding advantage and they become dominant. This results in low density flocs which do not settle easily and are carried over from the final settlement tank into the treated effluent. The traditional solution to sludge bulking is


the addition of flocculating chemicals to improve floc settlement, but this is neither environmentally friendly nor sustainable. An alternative solution is selectively to “cull”


the filamentous bacteria to manage their population at a level where they are useful. One way of doing this is to use an Advanced Oxidation Process (AOP), to which they are particularly susceptible. The te-ion technology works by passing atmospheric air through an


3 SEPTEMBER 2022 | PROCESS & CONTROL 4 Figure 1: Significant reduction


in the floating sludge after only a week of te-ion advanced oxidation treatment


electrical glow discharge generating a non- thermal plasma to produce a range of “reactive oxygen” species including peroxide, ozone and free hydroxyl radicals. The plasma containing the reactive oxygen species is introduced into the wastewater by a submerged turbine. A trial at a dairy demonstrated that the technology is highly effective at reducing filamentous bacteria growth and preventing sludge bulking.


Installed at a Climate Positive Dairy The Tirol Milch dairy in Wörgl, Austria, is one of the most modern and sustainable dairies in Central Europe; and is the first to be recognised as climate-positive. • The dairy produces a range of products


including butter, creams, yogurts and award- winning speciality cheeses • It is owned by a rural dairy cooperative of almost 10,000 farmers


The Tirol Milch dairy demonstrates how


sludge bulking suppression can be achieved easily by selective destruction of filamentous bacteria like Microthrix and Nocardia without the need for flocculating chemicals. Compared to typical chemical based


solutions, te-ion gives far greater floc settleability, without affecting the biological treatment processes. “The use of te-ion technology has shown how the performance of our biological treatment plant can be improved in a sustainable way”, said Tirol Milch Managing Director Josef Braunshofer, “and contributed to us becoming climate positive.” te-ion advanced oxidation technology is


available from Te-Tech Process Solutions in the UK and SFC Umwelttechnik in Austria.


Te-Tech Process Solutions www.te-tech.co.uk


astewater from the food and beverage industries is usually readily biodegradable and can, therefore,


/day of high COD wastewater is


treated by an on-site activated sludge plant, however the dairy found a problem: sludge bulking. A dense brown foam had formed on the surface of the tank and this floating sludge was causing poor quality treated water and odour problems – both common problems in activated sludge plants in both municipal and industrial applications. Tirol Milch wanted an environmentally


friendly solution and chose to stay clear of chemicals solutions. They decided to use te- ion advanced oxidation technology and the system was installed at Tirol Milch dairy’s 7,000m3


operation, the floating sludge had reduced significantly, as shown in Figure 1.


aeration tank. After only one week of


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