"Paper Mill with lagoon system facing pressure to install activated sludge" - Should the change ~ or can existing system be developed for more efficiency?
A large paper mill in southern Georgia is facing increasing pressure to reduce color and odors of their effluent entering into a river system where their daily discharge makes a significant change in river aesthetic quality below the mill. The immediate suggestion by experts if for the mill to replace their large aerated lagoon system with the "latest" in activated sludge treatment systems. Such a system would be smaller in foot print - freeing up land, but would cost hundreds of millions to build and have very high ongoing operational costs. My questions is ~ can this paper mill use existing lagoons more efficiently and improve effluent quality with less initial capital outlay and no significant increase in operational cots?
Most paper mill lagoons in the US contain earthen basins for water retention and high speed surface aerators to providing for oxygen used by the microbes. Biological solids are removed in polishing ponds which require periodic dredging of sludge to maintain volume.
While the high speed aerators are efficient in adding dissolved oxygen - approximately 2 lb O2/hp/hr. They are less efficient in mixing and result in sludge buildup just outside the zone of influence. As sludge builds, wastewater treatment volume is reduced and short-circuiting of flows becomes an issue. In ares with electric lines and aerators, the mill cannot easily dredge the solids so occasional aerators are moved to help prevent excessive sludge buildup.
While I am not involved with the mill's upgrade proces, I would usually start my optimization process with the following steps.
Action Steps Based on Survey Data - Changes to Intensive Biological Treatment Zone
Polishing Pond - Improvements
Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.
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