GB2400846A

GB2400846A - Sewage treatment on boats, using membrane filters

Info

Publication number: GB2400846A
Application number: GB0309380A
Authority: GB
Inventors: Alan John Ford
Original assignee: Aquator Group Ltd
Current assignee: Aquator Group Ltd
Priority date: 2003-04-25
Filing date: 2003-04-25
Publication date: 2004-10-27
Anticipated expiration: 2023-04-25
Also published as: GB2400846B; GB0309380D0

Abstract

Sewage treatment apparatus suitable for use in a marine vessel comprises a first space (1) for receiving sewage, a second space (2) containing a membrane treatment unit (17) and means (13) for supplying sewage from the first space to the second space. Preferably the apparatus includes air diffusers.

Description

SEWAGE TREATMENT

The present invention relates to sewage treatment.

Traditionally, marine vessels have used bilge tanks for the storage of untreated waste and then cleaned out their tanks at sea. This is now an unacceptable practice.

Existing onboard sewage treatment works have high energy and low fixed capacity and discharge quality, usually requiring additional chemical treatment such as chlorine.

These plants cannot begin immediate treatment due to the need for establishment and build up of bacteria, and can initially pollute and smell.

According to the present invention, there is provided sewage treatment apparatus suitable for use in a marine vessel, comprising a first space for receiving sewage, a second space containing a membrane treatment unit and means for supplying sewage from the first space to the second space.

The apparatus could include means for supplying sewage into the first space.

The apparatus could include filter means, for example in the first space, in the path of sewage from the first space to the second space.

The apparatus could include air diffusing means in the first space coupled to air supply means.

The second space could include air diffusing means coupled to air supply means.

The apparatus could include means for lifting the membrane unit out of the second space.

At least one of the first and second spaces could comprise a tank.

The present invention will now be described, by way of example, with reference to the accompanying drawing which is a schematic diagram of an example of apparatus according to the invention.

The following example relates to a membrane sewage treatment plant, for treatment of unscreened human effluent (blackwater) waste for population equivalents in the range 6 to 20. Treatment can ensure discharge of water to a standard exceeding the requirements of the regulatory bodies. The plant is intended to serve small boats, barges, houseboats or any vessel with a small crew/passenger complement when not connected to any harbour, riverside or local utility sewer facility.

The discharge does not require to be held within storage tanks for shore or riverside disposal. Because high water recovery rate and quality can be enabled, the discharge can be safe to be recycled for use to wash down the vessels, flushing of toilets, further treatment such as reverse osmosis to create drinking water or direct discharge into the sea or river, dependent on local bylaws and international regulations.

The example is not intended to treat greywater, i.e. waste water from sinks, showers and washing machines, thus enabling the load on the plant to be reduced by as much as 90%.

The example enables the provision of a pre-designed and built, compact plant with variable capacity and high quality discharge that can be rapidly delivered to site. Its small footprint and low weight when empty, allow it to be rapidly deployed and/or built into the vessel and arranged to suit the available space.

The example provides an entire treatment system in two factory-assembled units, a holding tank and a second tank with a membrane treatment unit, with separately located air blowers, control and monitoring systems. The construction is maintenance free due to GRP (glass reinforced product) or stainless steel materials.

On existing vessels it may be possible to re-use the existing bilge tanks as the holding tank. Any new holding tank, where needed, will be specially designed to achieve optimum use of available space.

Transfer from toilet to the holding tank and holding tank to the second, treatment tank is via manual or electric bilge pumps. Alternatively, gravity transfer could be used, when space considerations allow.

The plant is immediately able to treat waste due to "seeding" with existing bacteria combined with membrane filtration and aeration. Without seeding it can maintain permissible, initial discharge standards until naturally occurring bacteria become established.

Both tanks are aerated via diffusers, keeping the contents sweet, preventing any foul smell or gases under normal operating conditions and vented to above deck.

Control devices and the air blowers are driven using low voltages, reducing the risk of electrocution and enabling the direct use of existing lead acid batteries or alternate technologies such as wind or solar power. The air blowers are specially designed for sewage treatment having high efficiency and low noise/vibration levels.

Due to the simplicity of design, alarm systems, pre-programmed control systems and no moving parts within the tanks, the plant will function unattended. Only low levels of semi-skilled labour are required to carry out inspection and maintenance. Any faulty items can be replaced on site and subsequently refurbished or disposed of by the manufacturer.

There is no need under normal conditions for personnel to enter the tanks, thus avoiding having to drain tanks and the unpleasantness of entering a confined space and inherent risk to life from infection or dangerous/foul gases.

When membrane units require cleaning, this will be carried out by substitution at site and return to manufacturer for specialist cleaning. They are submerged in the treatment tank and can be lifted out through the access way via attached chains or strops. All pipe attachments are via flexible hoses. Joints to the membrane unit are connected while the membrane unit is out of the tank.

As shown in the drawing, an example of plant according to the invention comprises two tanks (installed below deck in use of the plant) - a holding tank 1 and a treatment tank 2. On top of the tanks are mounted hatches 3. The hatches 3 allow access into the tanks, protect the user and prevent loss of sewage, ingress of foreign matter and release of foul smells below deck.

Sewage leaves toilets via a bilge pump 4 and transfers to holding tank 1 through a port Exiting tank 1 are three more ports 6, 7 and 8. Port 6 is a drain-down port for tank l, port 7 is an overflow port and port 8 transfers to treatment tank 2. The outlet to port 8 is fitted with a coarse filter screen 9, preventing pass-over of large solids.

Fitted within tank I is a diffuser 10, fed with air from a blower 11. The air also scours the filter screen 9, preventing blockages.

Waste from port 8 of tank I transfers to port 12 of tank 2 via a bilge pump 13. Tank 2 is fitted with additional ports 14 and l 5. Port 14 is a drain-down for tank 2 and port 15 is the final outlet port whose discharge is regulated via a valve 16.

Contained within tank 2 is a membrane unit 17. At the base of the unit is fitted an air diffuser 18 which oxygenates the water. Fitted to the top of the unit is a manifold 19 linked to valve 16 via a flexible hose 20. Fitted to the side and top ofthe membrane unit 17 are two chains or strops 21, which prevent the unit from falling over during inclement weather and are used to lift the unit in and out ofthe tank 2 during the yearly cleaning routine. Diffuser 18 is fed with air from a blower 22.

The membrane unit 17 comprises a plurality of adjacent membrane treatment panels for sewage and/or liquid waste treatment and of a kind known in the art - see for example EP-A-0510328,EP-A-0602560,EP-A-0662341,EP-A- 1 121971 and US-A-5 772 831.

Levels and overflow alarms are controlled through level gauges 23 and 24. -s -

Separate vents 25 ventilate tanks 1 and 2 to above deck and are installed into the bilge lines.

Separately supplied is a control panel which supplies and controls all electrics and instruments. Incoming electrical supply connects at this point supplied by the user.

Claims

] . Sewage treatment apparatus suitable for use in a marine vessel, comprising a first space for receiving sewage, a second space containing a membrane treatment unit and means for supplying sewage from the first space to the second space.
2. Apparatus according to claim 1, including means for supplying sewage into the first space.
3. Apparatus according to claim 1 or 2, including filter means in the path of sewage from the first space to the second space.
4. Apparatus according to claim 3, wherein the filter means is in the first space.
5. Apparatus according to any preceding claim, including air diffusing means in the first space coupled to air supply means.
6. Apparatus according to any preceding claim, wherein the second space includes air diffusing means coupled to air supply means.
7. Apparatus according to any preceding claim, including means for rifling the membrane unit out of the second space.
8. Apparatus according to any preceding claim, wherein at least one of the first and second spaces comprises a tank.
9. Sewage treatment apparatus, substantially as herein described with reference to the accompanying drawing.