Nanotech manufactures mobile water purification systems based on feed water characteristics and customer requirements. Our systems range from the smallest system, handling 200 l/hr, right up to those handling 1.2 million l/hr. These units are containerised, making it easy to ship them to different locations. Our systems include disinfection processes downstream, to guarantee drinking water free from bacteria and viruses.

General process description The flow diagram below shows a typical ultrafiltration (UF) system using membrane technology. The system consists of a feed pump, strainer, rack equipped with UF modules, filtrate/backwash tank and backwash tank. Based on feed water quality, an in-line coagulation system and a dosing system for chemical backwashes can be added. The chemical backwash system can comprise dosing systems for disinfection; sodium hypo chlorite (NaOCl), caustic (NaOH) and acid (HCl or H2SO4) cleans, again depending on feed water characteristics.

The raw water is introduced into the UF modules via a pump. Before it enters the modules, it passes through a strainer which filters coarse particles to protect the membranes.

An inline coagulation device can be installed to improve filtration performance and backwash efficiency with certain water types. The raw water passes through the UF membrane and is delivered to the filtrate/backwash tank. Periodically, the membranes are backwashed to remove debris accumulated on the membrane surface. Water used for the backwash is taken from the filtrate/backwash tank. Chemical dosing into the backwash water can be performed to enhance backwash efficiency.

	General design features The dizzer UF modules are available in different sizes. Each module is provided complete with pressure housing and end caps, making it possible to install them as single units. No additional pressure vessels and no additional on site assembly work are necessary. The modules can be easily mounted and dismantled. The dizzer modules are designed for vertical installation, making it easy to vent the modules and the complete UF system in an efficient and reliable way. Vertical installation also improves the efficiency of an integrity test. During the integrity test, an integrated transparent top feed connector helps identify any defective modules. Operating mode can be either dead-end or cross-flow, dead-end being the preferred operating mode in most applications for reasons of economy. The modules are normally fed with feed water from the bottom and backwashed with the debris water, leaving the top port. However, the design of the dizzer modules also allows feed water to be introduced from the top or bottom in an alternating mode, to evenly distribute the contaminants along the fibre and facilitate their removal. This is particularly useful with more challenging feed water.
	Removal capabilities
The most critical water contaminants removed by UF are: Cryptosporidia In extensive tests carried out it was proved that cryptosporidia (at a size of 4" 6"m) were rejected by the dizzer module to an extent of more than > 6 log. Turbidity The most important characteristic in terms of turbidity reduction is that the turbidity in the filtrate of the dizzer modules is completely independent of the turbidity level in the feedwater. Even during turbidity peaks in the feed water the dizzer modules ensure a consistently superior filtrate quality, usually lower than 0.1 NTU. SDI The fouling index SDI is one of the main criteria used to evaluate water quality, particularly in regard to sea water. UF as a pre-treatment to reverse osmosis seawater plants is becoming widely popular. In general, an SDI of less than 3 is requested for reverse osmosis feedwater. The reduction in SDI value is primarily dependent on the constituents in the feedwater to the UF system. In addition to particles and suspended solids, colloidal contaminants and dissolved organic substances also have an impact on the SDI. Particle and colloidal substances can be removed completely by UF, whereas the rejection of dissolved organic matter depends largely on the size of the molecules. By dosing coagulant into the feedwater, the rejection of organics and the consequent reduction of the SDI can be improved significantly. Depending on the raw water and operating conditions, the filtrate SDI is usually in the range of 0.5 to 3. Reduction of TOC By definition, TOC comprises all types of organic carbons found in particles, colloidal substances and dissolved organic matter. The rejection of TOC by UF depends mainly on its molecular weight and shape. Adding coagulant in front of the UF helps increase the overall rejection rate of TOC, particularly of low molecular weight organic matters. The TOC rejection rate can be increased by optimising the amount of coagulant added to the feed water and the pH level. In contrast to conventional treatments, it is not necessary to monitor sedimentation or filterability of the flocs, since UF performance is not dependent on floc geometry and specific weight. TOC removal of UF can reach up to 60%. TOC reduction without coagulant 0 - 25% TOC reduction with coagulant 25% - 60%