Waste Water Re-use

Waste incineration generates a high humidity flue gas that alsocontains contaminants due to fuel. Flue gas condensing is a cost-efective and ecological way to increase the boiler's district heat production. The condensate formed in flue gas condensation is with proper treatment usable to replace potable water as raw water. Due to the specific challenges of waste incineration, the Sofi process delivered does not discharge any water into the sewer.

FLUE gas treatment and flue gas dead-end

With the Sofi process (MF and RO) approximately 75% of the condensate is gained as makeup water for district heating. Treated condensate is solids free low conductivity (< 150 µS/cm) water. Reverse osmosis uses high temperature membranes with a maximum operating temperature of 85 ° C. This, in addition to water recovery, allows for heat recovery without extra investment in heat exchangers.

District Heating Network

In CHP plant, even a small amount of very fine particle contamination, e.g. magnetite below 1 µm, lowers the efciency of the heat distribution system and may result to uncertainty in measurement equipment. The solids are removed from side stream by automatic Sofi Filter unit.

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In Sofi Filtration’s solution the waste water is fed to a settling tank with a screw conveyor which removes the solids.

The overflow of the settling tank is pumped to Sofi Filter via a centrifugal pump. Due to the filter’s cross-flow design, part of the feed flows through the filter element and part returns to the process. In this application Sofi Filter is equipped with a 10 µm metal wire mesh element. The filtrate from Sofi Filter can be drained or reused. Sofi Filter reduces the amount of water in the settling tank and concentrates the solids so that they can be removed with the screw conveyor.


The outlook for US crude oil is expected to grow through 2022 from 10 MMbpd in 2018 to 11-12 MMbpd. Similarly, Natural gas production is expected to grow at 5% per year from 29 to 34 Tcf. Thegrowth of this industry is often in regions of water shortages.

The large amount of Produced and Flowback water can be reused or disposed of in salt water disposal wells. In either case, filtration is a required operation, in particular, at levels less than 20 and often less than 5 microns. Salt water disposal wells need to maintain permeability to keep operating and to minimize seismic disruptions. Similarly water reuse requires filtration solutions to protect downstream membranes and equipment. Theseoperations need robust filtration solutions to handle flows of 2000 to 30,000 bpd or more.