What could be the most worthy alternative solution for the problem below?

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What could be the most worthy alternative solution for the problem below?

Created March 12, 2012 by George Rybakov 简体中文 Русский

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An island in the South Western part of Finland has 200+ households; each (on average) equipped with decentralized two pipes (tanks) sewage system. Fresh water is taken from ground water. Most of the houses lie in the distance of less than 170 meters from the sea, which means that the strictest discharge limits for BOD, P and N removal are applied. The city has supported a project of centralized pipeline connection of the most houses to the water supply and sewage. The distance from the island to the main land is significant (more than 20-30 km). Most of the pipe is planned on the sea bottom the Gulf. What are the alternatives, which could meet the discharge limit requirements and not that expensive as the pipeline solution?

March 12, 2012 by George Rybakov 简体中文 Русский

George, what you need is an on island independent small water/wastewater treatment plant. You can find these as full container installations, with varying technolgogies. The benefit's of on island system are the price and self sufficiency, whereas the benefit of the central mainland connection is the ease of use (point of service for the city is the inlet of the pipe). I'm remain a bit unclear on the current freshwater solution, but If centralized solutions to that are needed for that also, I would recommend membrane technologies for both groundwater and seawater, preferrably nanofiltration and reverse osmosis. As for the wastewater I would recommend combining a basic chemical-biological system with membranes, e.g. chemical P removal, biological BOD+N removal and to install a membrane at the end to replace flotation/sedimentation and to enhance sludge thickening. Of course with an on island wastewater treatment you will have the problem of the remaining sludge and operation of the system, but these can be managed in connection with the municipal waste treatment. Anyhow, theres plenty of these types of small scale solutions available, also from Doranova. For actual technical and price information, Irecommend contacting e.g. Doranova's water and waste division directly.

March 13, 2012 by Jarno Laitinen 简体中文 Русский

Jarno, thanks a lot. Very useful information. The only thing left for our case is to persuade our local people to consider other options as well. BTW, how much space (m2) does such a site need?

April 02, 2012 by George Rybakov 简体中文 Русский

With 200+ inhabitants and without large scale industry, I would estimate the nominal flow capacity to be 1,5 m3/h. Normal membrane fluxes range around 20-100 l/m2/h (lmh) and the surfacwe areas from 1-20 m2 (depending on application and technology). In short, the size of your required unit would be neatly packed into a 20' or 40' FCL, depending on the size of the tank system, so the footprint (m2) would be 3*6 - 3*12 m.

April 03, 2012 by Jarno Laitinen 简体中文 Русский

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What could be the most worthy alternative solution for the problem below?

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