Whereas hi COD-loaded industrial waste waters have to be treated, whereas a traditional activated sludge plants would require huge basins and very high operating costs, it’s convenient to prior treat them in an anaerobic stage. This phase would allow, with minimal power consumption, to reduce about 80-95 % of organic load, because it’s converted in biogas.
Afterwards, if purification it’s rate not enough strong because of restrictive discharge limits, water coming out from anaerobic stage can be further treated in a subsequent aerobic stage.
The strengths of anaerobic + aerobic combination are evident:
80 – 95 % COD reduction with low power demand
Strong reduction of size, erection and operational costs of subsequent aerobic stage, because it has to treat water with organic load about 5 to 20 times lower
Much lower (up to 10 times) exceeding sludge production
Biogas production, which can be reused or converted in electric and thermal energy by mean of a cogenerator
Anaerobic digestion, particularly when applied to industrial waste waters, where hi-loaded reactors must be used because of high organic and hydraulic load (otherwise huge basins should be foreseen), it’s a fine process by itself which, to well work, must comply with several biological and functional balances. That’s the reason why we’ve choosen the simplest and reliable technologies, excluding the complex ones (i.e: UASB reactors, fluidized bed reactors…), such as downflow moving bed biologic filters:
The reactor is feeded from the top
Biomass lives and grows attached to specific plastic supports floating in the upper part
Treated water comes out from the bottom
Basing on our experiences, this configuration is the more reliable and stable, being the less affected by loading and/or environment fluctuations.