a filtering method, with which a fluid to be filtered is led through a filter (4), the filter (4) is back-flushed at regular time intervals and a pre-treatment agent is added to the fluid at the entry side of the filter. A process variable which describes the efficiency of the filtration is continuously computed during the filtration, and a metering quantity of the pre-treatment agent is reset on the basis of the values for the process variable or a characteristic values derived from this.

The disclosure provides tangential flow depth filtration (TFDF) systems which exhibit improved filter fluxes and process capacities and reduced fouling characteristics. The TFDF systems of the disclosure optionally utilize tubular depth filters (TDF). Methods are provided which include the passage of a non-laminar flow through at least a portion of a length of a TDF in a TFDF system.

A potable water producing system for disposition at a salt water body and methods of producing potable water are provided. The system includes a wave energy conversion system (AWECS) and a portable filtration system. The AWECS forms a floating articulated barge having an onboard desalination system including reverse osmosis membranes. The filtration system is a sand filter residing on a damping plate submerged in the salt water body and filters the adjacent salt water for providing filtered salt water to the onboard desalination system. Wave action on the articulated barge provides energy to pump and pressurize the filtered salt water from the sand filter to the reverse osmosis membranes to produce potable water. The wave action on the articulated barge effects shaking of the reverse osmosis membranes, thereby rendering them self-cleaning. The potable water can be used for various applications, e.g., bottling, replenishing aquifers, ground and/or aquifer remediation, irrigation, etc.