The supply of drinking water is a major challenge for developing countries, especially when faced with emergency situations. Objectives in such times are to quickly supply populations with sustainable drinking water solutions. Short delivery and commissioning times are crucial.

Certain solutions offer access to drinking water without requiring major engineering works or special technical expertise to help install them.

For example, with Degrémont Technologies' compact UCD units, the company will supervise the assembly and commission of the units once the civil engineering works are finalised (concrete slab and pumping). Local teams also undergo training so they can help manage and maintain installations.

In order to comply with localised constraints of the areas concerned, each project is conducted in partnership with a network of local service providers.

Studies are then carried out on the quality of the water to be treated, to ensure the drinking water supply meets international standards defined by the World Health Organization.

Requiring low power, the UCD process design integrates a coagulation-flocculation chamber, a settling area, and pressure filtration with water and air scour backwash. The civil works required for installation are confined to a concrete slab and drainage pipe connected to the sewer. The UCD drinking treatment plant is based on a compact conventional process: coagulation, flocculation, lamellar clarification, sand filtration and chlorine disinfection.

Sludge extraction is automatic. This automation is based on relay type actuation, which is very simple to maintain in remote areas. Several options are available taking into account water treatment requirement (automation with PLC, aeration, pre-oxidation, UV, active carbon filtration, etc.) and chemical reagents available in the country. So how does the process work?

After a coagulant is applied, the raw water flows into a flocculation chamber to increase the size and cohesion of the floc. A clarifier equipped with lamellar modules is used to accelerate the separation of the floc. Sludge stored in the lower position of the separator is withdrawn automatically at regular intervals.

Water is then transferred from the flocculation compartment to the settling tank via a stilling chamber located beneath the lamellar modules. Settled water is collected in the settling tank overflow and pumped to the filters. Inside the filters, water is distributed above the filter media and flows down through the sand, which traps the suspended solids. Nozzles fitted on the filter floor collect the water evenly. Chlorinated solution is then injected in line to filtered water for disinfection purpose.

Backwashing then uses filtered water from the operating filter, coupled with air scour. This design aims to clean the filter media thoroughly, minimise the duration of the backwash cycle and eliminate the need for a backwash water tank and pump.