Transportable reverse osmosis water purification unit

• US 5,244,579 A
• Filed: 10/09/1992
• Issued: 09/14/1993
• Est. Priority Date: 10/09/1992
• Status: Expired due to Fees

• Current Assignee: Zenon Technology Partnership
• Original Assignee: Zenon Environmental Incorporated (Veolia Environnement SA)
• Inventors: Whiting, Douglas R., Horner, Kenneth J.
• Primary Examiner(s): Dawson, Robert A.
• Assistant Examiner(s): Fortuna, Ana M.
• Application Number:
  US07/958,086
• Time in Patent Office: 340 Days
• Field of Search: 210/652, 210/195.2, 210/257.2, 210/636, 210/791, 210/282, 210/264, 210/333.1, 210/333.01, 210/275
• US Class Current: 210/652
• CPC Class Codes: B01D 2311/04 Specific process operations in the feed stream; Feed pretreatment
• CPC Class Codes: B01D 2311/103 Heating
• CPC Class Codes: B01D 2311/14 Pressure control
• CPC Class Codes: B01D 2311/16 Flow or flux control
• CPC Class Codes: B01D 2321/04 Backflushing
• CPC Class Codes: B01D 2321/16 Use of chemical agents
• CPC Class Codes: B01D 61/025 Reverse osmosis; Hyperfiltration
• CPC Class Codes: B01D 61/026 comprising multiple reverse osmosis steps
• CPC Class Codes: B01D 61/04 Feed pretreatment
• CPC Class Codes: B01D 61/06 Energy recovery
• CPC Class Codes: B01D 61/08 Apparatus therefor
• CPC Class Codes: B01D 61/10 Accessories; Auxiliary operations
• CPC Class Codes: B01D 65/02 Membrane cleaning or sterilisation ; Membrane regeneration
• CPC Class Codes: C02F 1/441 by reverse osmosis
• CPC Class Codes: C02F 9/20 Portable or detachable small-scale multistage treatment devices, e.g. point of use or laboratory water purification systems

Abstract

A self-contained, transportable reverse osmosis water purification unit has a limited throughput of no more than about 20 gpm of permeate in a single pass operation with reverse osmosis ("RO") modules which can be cleaned in place. When raw water is particularly fouled, the unit is operated in a double pass operation in which the permeate from the first pass is used as feed for a second RO module. The unit, referred to as a "purification container" "PC" or an ADROWPU because the PC is air-deliverable, comprises an enclosed weather-tight housing having a base on which the major components are removably mounted. For transportability, the PC has the overall dimensions of an ISO container, and is fitted with means to load and unload it on standard carriers. A high pressure pump is required to feed water freed from suspended solids to the RO modules. The pump also delivers concentrate to a bladder tank where the concentrate is stored under pressure (about 100 psig) to flush a coarse filter automatically when it is plugged, which is often. Fine filters for solids removal are not plugged too often and can be replaced when the unit is not producing permeate. The ADROWPU is unique because of the economy of components used to produce a relatively large amount of permeate from any available raw water source. The placement of the components symmetrically about the center of mass of the PC is essential to allow the PC to be loaded and unloaded uneventfully, even if it is delivered by a helicopter.

Claims

1. A self-contained, transportable reverse osmosis water purification unit having a throughput of no more than about 20 gpm of permeate in a single pass operation, said unit comprising,

an enclosed weather-tight housing having a continuous base integrally combined with said housing to form a purification container having the overall dimensions of an ISO container, said purification container 5.5 m long×

2.1 m wide×

1.7 m high being adapted to be demountably disposed in a transport means from which said purification container may be deployed without due care, to land on the ground in a horizontal position, right-side-up;

an A-frame integrally combined with said base, each including attachment means for deploying said container;

hydrocarbon fuel-powered generating means for generating sufficient electricity at a voltage required to operate all components powered by electricity, and storage means for storing enough fuel to operate said generating means for a predetermined period of time;

said housing being divided into first and second enclosed compartments separated from one another by a dividing wall, said second compartment having said fuel storage means, and said generating means including electrical control means therefor and a storage battery, housed in said second compartment;

said first compartment having housed therein substantially all remaining components for purifying raw contaminated water, said components including, a first pass reverse osmosis module and a second pass reverse osmosis module;

a feed pump, a booster pump, first pass and second pass process pumps, and a chlorine injection pump;

first pass and second pass reverse osmosis modules having reverse osmosis elements disposed therein;

coarse filter means and fine filter means;

a bladder tank having a capacity of at least 17 gal;

a cleaning tank having a capacity of at least 30 gal; and

, control means to operate said components to deliver no more than 20 gpm of permeate in a single pass operation;

said first and second compartments having equipment therein demountably secured to said base and interior surfaces of said compartments with shock-absorbing means, said equipment being essentially symmetrically distributed about the center of mass of said container,

whereby said container may be unloaded from a supporting surface above the ground and land thereon, base first, and remain oriented in a substantially vertical position.

2. The purification unit of claim 1 wherein said coarse filter means includes automatic self-cleaning means adapted to back-wash said coarse filter means without interruption of flow of raw water to said fine filter means, and without utilizing a source of water other than stored concentrate.

3. The purification unit of claim 2 wherein said first pass module comprises plural modules connected in series, so as to flow concentrate from the first as feed to the second, the permeates and concentrates from said plural modules being respectively combined;

and, said second pass comprises a single second pass module connected in selective permeate-flow-communication with said first pass modules so as to flow said permeates as feed to said second pass module.

4. The purification unit of claim 3 wherein said self-cleaning means is in selective fluid communication with concentrate stored in said bladder tank, and said concentrate is pumplessly delivered to said self-cleaning means.

5. The purification unit of claim 4 including conduit and valving means to chemically clean said first pass modules and said second pass module, separately, without removing said reverse osmosis elements from within said modules, and without utilizing a source of water other than permeate.

6. The purification unit of claim 1 wherein said fine filter comprises a combination of a 50 μ

m screen filter disposed upstream plural 5 μ

m-15 μ

m cartridge filters.

7. A process for delivering no more than 20 gpm of permeate from reverse osmosis modules housed in a transportable container constructed to have fixedly disposed therein all equipment including instrumentation to control operation thereof, said process comprising, providing a purification container no larger than an ISO container 5.5m long×

2.1 m wide×

1.7 m high filtering brackish water through a combination of a coarse screen filter having openings no larger than 300 μ

m, and a fine filter having openings no larger than 100 μ

m to produce filtered water;

automatically back-flushing said coarse filter when it is sufficiently fouled to provide a pressure drop sufficiently high to indicate an unacceptable constriction of flow;

flowing said filtered water through at least one pass of reverse osmosis modules;

recovering said permeate; and

, storing a portion of concentrate from at least one of said reverse osmosis modules, under elevated pressure above that required to back-flush said coarse filter, the amount of concentrate stored being sufficient to back-flush said coarse filter; and

, periodically replacing said fine filter means without interrupting production of permeate.

8. A process for cleaning a fouled reverse osmosis membrane used in either a first pass operation or a second pass operation of a reverse osmosis subsystem in an air deliverable reverse osmosis purification unit, comprising, diverting permeate to a cleaning tank in which no permeate is stored to be made up into a chemical cleaning solution;

adding appropriate chemicals to diverted permeate in the tank to form said cleaning solution;

flowing said cleaning solution to the suction side of a booster pump used to pump incoming water into filters prior to being introduced into said unit; and

, diverting said cleaning solution discharged by said booster pump to a fouled membrane to be cleaned.