A growing group of ready-made, often high-tech commercially available combined treatment processes for semi-centralized use. Widespread examples include the Jal-TARA (slow sand filtration, with different layers and fabric filter), the Naiade (fine filter screens and UV) and the Perfector-E (microstrainers and ultrafiltration, originally for emergencies). Often used as stand-alone installations.
Prices widely vary from USD 50-40,000/unit. Taking into account the yield and lifetime, costs of water in USD/m3 vary from USD 0.02-0.69/m3. Ultrafiltration is the most expensive and the electrolysis-based chlorination is the least expensive one.
Commercial units are often designed for minimal maintenance. And since they are often used without other processes, the management is easier than that of conventional, centralized treatment installations. Training for of managers for maintenance and regular water quality controls necessary.
Compared to conventional treatment processes, these combined units have higher energy requirements and tend to have a higher ecological footprint. The contaminated sludge or concentrate needs to be handled safely in order to avoid the contaminants reaching users.
Conventional water treatment processes are elaborated and combined for stand-alone use. Often specific materials used which are not locally available. Methods are relatively high-tech. Requirements for operation and maintenance are minimal. Main activity is regular cleaning of the filter material.
Water may be more expensive when compared to water from conventional treatment, increasing user resistance. Some options offer limited water safety: Jal-TARA only partly removes viruses and WATA only partly removes protozoa, posing health risk to the users.
No relevant remarks for Commercial multi-treatment units.