Textile is a growing industry in which dyeing, bleaching, printing and finishing grey fabrics uses large amounts of water. Treatment of this textile wastewater is difficult due to the variety of materials and processes used in textile manufacturing. The contaminants in the water often contain organics, deflocculation agents, finishing agents and surfactants which can lead to membrane wetting and/or fouling. Also, moderate salt content is often present. Conventional biological treatment and/or foam fractionation is frequently used as a suitable pre-treatment for further concentration of the salt content to volume reduction of the wastewater towards zero liquid discharge. Conventional concentration of these wastewater streams requires thermal desalination techniques like multi-effect evaporation and mechanical vapor compression.
Downside of these conventional techniques are the high costs of used materials and high energy consumption. Membrane distillation uses a hydrophobic membrane preventing the polluted liquid to pass while water vapour can. Using a hydrophobic membrane allows a a decrease in vapor space requirement and a high mass transfer area per volume of equipment compared to conventional techniques. Exotic expensive metal alloys are replaced with high resistant plastic material to prevent corrosion. Membrane distillation powered by the waste heat of textile factories allows in one step to reduce significantly the water consumption in textile factories, moving towards zero liquid discharge.
In the oil & gas industry, a great amount of water is injected into the reservoir to counteract the subsoil pressure and achieve high recovery levels. As this liquid reemerges, it is enriched in valuable hydrocarbons and is referred to as ‘produced water’. The global production of produced water is estimated at 250 million barrels per day, with an increasing trend. This produced water contains several organic and inorganic components at variable concentrations, which creates the need of a complex design of cost-effective, flexible and low-footprint treatment plants to separate the oil and to obtain a water effluent with sufficient quality for further treatment, discharge or reuse. This problem is further exacerbated by the growing need to recycle the product for re-injection or reuse for beneficial purposes, e.g., irrigation, and in offshore applications, where space is limited and compactness is required.
The discharge of the treated water is of environmental concern for both soil and water, so it is strictly regulated. Thus, the emerging thermally-driven membrane process of membrane distillation (MD) has a great potential for the treatment of produced water since it can achieve high water recovery rates from feeds that are highly saline. This process becomes especially competitive when low exergy heat is available as energy source, which is the case of many oil & gas extraction fields, where stream temperatures can exceed 100 °C due to geothermal heat. Membrane distillation powered by incineration of waste gas allows oil & gas wells to reduce transport costs significantly by locally desalinating in one step the produced water of their small/remote production sites.
In many offshore, marine and off-grid locations generator sets are used to provide electricity. In these applications, as they are not connected to the grid, there is also a need for fresh water. Most of these applications are using existing technology like reverse osmosis (RO) to provide this need. RO however is consuming large quantities of electricity increasing the size of the genset, increasing fuel consumption. Providing large quantities of fuel in these locations can be a very costly venture. Membrane distillation (MD) in contrast to RO is a thermal technology. While RO Is consuming electricity to achieve high pump pressures to produce clean water MD is consuming thermal energy, only using electricity to circulate water at low pressures. As it so happens generator sets produce, as a waste product, quantities of exergy (low quality) waste heat, this heat needs to be disposed of. MD being a thermally driven technology can consume this waste heat as input thermal energy for the process of MD. Providing both a cooling source for the generator sets and clean water. With changing demands in electricity, the operational parameters of the MD can be matched to the current waste heat production of the generator sets.
The drawback of this solution is that the amount of thermal energy available can be limited. Producing the highest possible amount of water using available energy can be desirable in these applications. Where other thermal technologies like MSF and MED are not suitable for these small scale applications, our membrane distillation solution is. Achieving high thermal efficiency at a small scale, using every bit of energy provided to produce the most amount of water possible. hydrophobic membranes act as a barrier to polluted streams allowing only clean water vapor to pass, removing up to 99.97% of contaminants in a single step producing safe water. Where existing technologies are limited in water recovery, membrane distillation is providing a reliable, energy efficient solution in a wide range of 0-14% salinity with minimal pre-treatment.
Sources of clean water in small rural/residential communities in remote sunny locations, not connected to the water and/or electricity grid, are becoming an increasing scarcity. These communities are in dire need of safe potable water suitable for irrigation. Many other pressure driven and thermal technologies are already trying to provide in these areas attempting to fill an increasing need for clean water. However, many of these technologies are not suitable, too costly or simply not able to provide for these small remote locations. With increasing environmental regulations protecting nature and wildlife, high water recovery has become a pressing issue. Combining the thermal power of the sun with membrane technology Aquastill seeks to provide clean water for these locations. Where other thermal technologies like MSF and MED are not suitable for these small scale applications, our membrane distillation solution is.
Achieving high thermal efficiency at a small scale using every bit of energy the sun provides to produce the most amount of water possible with the available thermal energy. Hydrophobic membranes act as a barrier to polluted streams allowing only clean water vapor to pass, removing up to 99.97% of contaminants in a single step producing safe water, potable and suitable for irrigation. As a stand-alone technology or working together with existing technologies to recover the most amount of water. Where existing technologies are limited in water recovery, membrane distillation is providing a reliable, energy efficient solution in a wide range of 0-14% salinity with minimal pre-treatment. Lowering environmental impact, helping people, helping nature.