An apparatus for batch closed circuit desalination of a salt water solution feed by reverse osmosis (RO) comprising:
- hydraulic power means (HP), hydraulic-arm (HA) means, RO means, and feed recharge means (FR), wherein
- said HP comprising a line of hydraulic fluid (HF) with a high pressure hydraulic pump for the delivery of pressurized HF from a hydraulic fluid reservoir (HFR) to said HA and thereby providing hydraulic power to said apparatus, a non-pressurized HF line for non-pressurized HF return from said HA to said HFR, and a two-way actuated valve means and a one-way check valve means configured to supply pressurized HF to said HA or alternatively to retrieve non-pressurized HF from said HA to said HFR;
- said HA comprising a single pressure vessel (PV) with a separation disc (SD) inside between said HF and said feed, or a plurality of said PVs connected in parallel, wherein HF is supplied from a first end of said HA whereas said feed and concentrates of said feed created inside said HA during RO desalination are supplied from a second end of said HA and the second end of said HA also comprises a mixing device (MD) means comprising an electric or electromagnetically driven mixer to enable blending of said concentrates inside said HA;
- said RO comprising a RO-skid with one or more modules of a selected number of membrane elements, with inlet and outlet lines connected in parallel, and a recycling line with a circulation means for closed circuit recycling of said concentrates blend inside said HA through said RO-skid, said circulation means comprising a circulation pump (CP) of low pressure difference;
- and
- said FR comprising a feed line with a low pressure supply means connected to said concentrates blend recycling line, a brine removal line extension from said concentrate recycling line, a two-way actuated valve means and a one-way check-valve means for controlling flow through the feed line, the concentrates blend recycling line, and the brine removal line extension to enable one of three discrete operations at a time:
- said concentrates blend recycling during RO, or said brine removal between RO sequences, or feed recharge of said HA between RO sequences also associated with said HF release to said HFR;
- said apparatus further comprising:
- online monitoring means of pressure on the inlet (Pin) and outlet (Pout) lines of said RO-skid, flow or volume on said recycling line down stream of said circulation means (FVCP), and flow or volume on said pressurized HF line to said HA (FVH);
- and
- a computerized control board means whereby operation of said apparatus is managed automatically on the basis of said online monitored data in conjunction with selected-flow rate and volume set-points.