Low-pressure sludge removal method and apparatus using coherent jet nozzles

A method for low-pressure cleaning of horizontal surfaces between vertical members arranged in a regular array comprising:

• introducing a cleaning apparatus into an opening provided adjacent the regular array;
• aligning each of a plurality of coherent flow nozzles provided on the cleaning apparatus with a respective intermember lane defined between two adjacent rows of the vertical members, each of the plurality of coherent flow nozzles comprising a plurality of closely aligned and closely spaced orifices, each orifice having an orifice bore length to orifice diameter ratio sufficient to produce a fully-developed low-pressure fluid jet;
• ejecting a separate and distinct coherent fluid jet of a cleaning solution through each individual one of the plurality of coherent flow nozzles such that with respect to each nozzle, fluid jets emitted from the plurality of orifices coalesce to produce a single larger coherent fluid jet ejected from the respective nozzle;
• and
• sweeping the jet from a proximal portion of the respective intermember lanes to a distal portion of the respective intermember lanes, thereby removing material from the respective intermember lanes.