Ultrafiltration for water treatment plant, TP 104-25

For research and treatment process development purposes Helsinki Region Environmental Services (later also "client" or "HSY") is in the process of acquiring an ultrafiltration (UF) unit to be retrofitted in an existing sand filter for Pitkäkoski water treatment plant (WTP). Long-term goal for the ultrafiltration pilot is to evaluate ultrafiltration paired with chemical precipitation as a primary natural organic matter (NOM) removal method when purifying cold surface water. Membrane performance and water quality is compared to that of a clarification and sand filtration. Purchased UF process will be preceded by a separate chemical dozing and flocculation unit to ensure effective NOM removal and membrane applicability in variable conditions. Different precipitation chemicals will be used, but the choice of chemicals and applied dose can be discussed with membrane supplier. In principle, the UF unit would be built in one of the existing sand filter pairs: one of the filters will be used for chemical dozing and flocculation, while the other one is reserved for UF units. The main targets in piloting are: - Adequate NOM removal - Act as an effective microbial barrier - Stable turbidity level in permeate from membrane filtration HSY have completed several laboratory scale tests for different UF processes, and the Client has decided to perform a full scale UF pilot based on ceramic submerged membrane filtration. Produced permeate from the ceramic UF unit will be further processed in Pitkäkoski WTP prior to distribution to customers. Pilot process lifetime is expected to be at least 50 years and membranes are assumed to be replaced during the piloting. The ceramic UF treatment could potentially be used in the future to further increase the capacity of Pitkäkoski WTP or as the primary treatment step in a new WTP in the Helsinki Metropolitan area. As the purchased membrane unit will replace part of the existing treatment process and membrane permeate is directed to further treatment, client will oblige actions from process supplier in case warranty clauses are not met.Main features of the procedureThe procurement was conducted using a competitive procedure with negotiation. Candidates meeting the minimum requirements were selected for negotiations based on the information provided in their requests to participate. The purpose of the negotiations was to specify and clarify the scope and technical content of the procurement, the quality of the technical solutions, commercial terms and project management arrangements. Following the negotiations, the selected candidates were invited to submit their final tenders.