1. Installation context
Customers do not always demand state-of-the-art innovation in industrial wastewater management: considering space and tight budgets for installation, it is often more useful to select a compact, easy-to-manage, and possibly scalable solution.
These are also the requests submitted to us in 2019 by a dairy company in Chile: the study of the client’s process water detects, as is often the case in the food industry and particularly in dairies, a significant load of biodegradable contaminants present in the effluent.
The required solution must therefore ensure efficient biological treatment, measurable by a reduction in BOD and total suspended solids. This is all downstream of treatment systems already present on the farm, i.e., dissolved air flotation units for solids-liquid separation.
Of course, two additional variables must be considered, as in most circumstances: containment of environmental impact and compliance with local regulatory standards.
2. Proposed solution
MITA Water Technologies opts with the customer to use rotating biological contactors: seven Biorulli® “biodiscs,” model B 290-60-1. This version has larger diameter plastic discs for an active biological treatment area of 6,360 m2 per disc. Power consumption of only 2 kW, concrete tank supplied by MITA.
The biodiscs of the Biorulli® system are placed horizontally on a shaft and rotate slowly (1 to 5 times per minute): the alternation between immersion in the effluent and contact with the air promotes the formation of bacterial flora on the plastic surface. It is precisely the bacteria that are responsible for the biological oxidation of organic contaminants and then independently detach themselves from the discs in the form of flakes: a matter easily removed by subsequent treatments.
It becomes clear that rotating biological contactors are an extremely simple (in terms of construction features, operation and maintenance) and at the same time extremely effective technology.
3. Results obtained
The removal of biological contaminants by the seven rotating biological contactors is truly remarkable, while equally remarkable in energy savings: tests have confirmed an output of treated water with a concentration of less than 30 mgBOD/l of total suspended solids, also considering compliance with food industry regulatory standards.
Operating and maintenance costs of Biorulli® systems will always be very low for MITA Water Technologies’ Chilean customer.
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