Industrial wastewater treatment – example 1

Some industrial waste-waters are inherently difficult to treat with conventional pressure-driven water treatment technologies due to a high content of fouling agents (TDS & TSS) and/or a high salt content. Examples include – but are in no means limited to – wastewater from the oil and gas industry, wastewater from wet scrubbers used to remove contaminants from sources of air pollution, and wastewater from the textile dying industry. In all the aforementioned applications, forward osmosis systems are a good low-energy alternative to installing expensive pre-treatment systems or using evaporators. Since disposal costs for industrial wastewater are mostly volume-based, the primary role of the forward osmosis system is to de-water the industrial wastewater to a point where disposal costs have been reduced to an acceptable level. In a continuous water treatment system, the water extracted through forward osmosis must be separated from the draw solutes in order to regenerate the osmotic strength of the draw solution. This process of water separation can be carried out by traditional pressure-driven membrane technologies, which are now operating directly on a diluted forward osmosis draw solution with greatly reduced fouling propensity. An important driver for designing forward osmosis based wastewater treatment systems with continuous draw solution generation is the simultaneous production of reusable water.

• Concentration
• Direct water production

Industrial wastewater treatment – example 2

In some industrial applications, the value of the wastewater treatment system lies in its ability to produce a dilutate without consumption of precious fresh water resources. One good example of such applications is fertigation,  an agricultural process where a forward osmosis system is used to extract clean water from impaired water sources into a concentrated liquid fertilizer solution. In the process, the liquid fertilizer solution becomes diluted to a point where substantially less fresh water resources are needed to produce the final fertilizer-containing irrigation water.

• Dilution (indirect water production)

Industrial wastewater treatment – example 3

One of the best application areas for forward osmosis systems can be found within the field of industrial process optimization. Imagine a factory/plant with two separate aqueous streams: one needs to be concentrated and another needs to be diluted. Traditionally these streams are treated separately but a forward osmosis system is able to utilize the osmotic pressure in the concentrated stream to extract water in a low energy fashion from the diluted stream. Thus, forward osmosis systems offer the possibility to replace two costly treatment processes with a single-step, low energy process. In our article about stand-alone forward osmosis systems we give an example of how forward osmosis technologies can be used for industrial process optimization in traditional RO-based desalination plants.

• Concentration
• Dilution (indirect water production)

Osmotic power generation – example 1

Osmotic power generation plants generate electricity from the osmotic pressure difference of two aqueous streams via the principle of pressure retarded osmosis (PRO). Briefly, PRO is a forward osmosis process where the  water extracted into the draw solution is used to generate hydraulic pressure, which in turn can run a turbine. Traditionally, osmotic power generation plants have been envisioned to utilize the osmotic pressure difference between river water and seawater.

• Energy production

Osmotic power generation – example 2

Forward osmosis systems capable of running in PRO mode could potentially also be used for combined osmotic power generation and industrial process optimization. The idea is to co-localize desalination plants and wastewater treatment plants and utilize the brine waste from the desalination plant to both dewater wastewater streams and at the same time generate electricity through pressure retarded osmosis. In the process, the brine waste becomes diluted to seawater salinity levels, thus, greatly reducing the cost of brine discharge.

• Energy production
• Dilution (indirect water production)
• Concentration