Sewage treatment plant

Details Sewage treatment plant Sewage treatment plant

1990-01-22

1991-04-09

Silverman, Stanley

Liquid purification or separation

Constituent mixture variation responsive

210104, 210143, 210202, 210220, 210258, 210259, C02F 320

Patent

active

050062328

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to the treatment of sewage and in particular, though not exclusively, to sewage treatment for use on a mobile platform such as a ship.
2. Discussion of Prior Art
Disposal of sewage from ships alongside or in coastal waters is a considerable current problem. Some harbours have sewage collection facilities, however, these are not always available. Thus sewage collection and treatment plant is required where port facilities are unavailable. Such plant is desirably highly efficient such that a small plant will allow a ship to remain alongside for a long period. Currently there are three types of sewage treatment plant in common use. These are: collection systems.


Biological Sewage Treatment Plants

Theoretically, this type of plant should allow ships to operate for long periods without the need for shore reception facilities. In practice they have not operated satisfactorily for the following reasons:
(a) The process depends upon effective reduction of the sewage by bacteria in the main aeration tank. This process is very sensitive to: leaking tank cleaning spray cross connection valves. ship. Low loads are particularly detrimental as the bacterial population necessary for aerobic digestion of the sewage cannot be sustained. bacterial population.
(b) Being continuous flow processes there is no control over the residence time in each tank. This can result in incomplete processing of the sewage and carry over of solids.
(c) Ship motions affect the settling process.


Solid Separation Treatment Plants

This type of plant has the advantage that it is available on demand and can be shut down when the ship is outside controlled waters. However, these plants have not been entirely satisfactory in service for the following reasons: standard expected to be set by international regulations. frequently and require considerable and unpleasant maintenance.


Collect, Hold and Transfer Systems

The majority of these fitted in the Royal Navy are of the gravity collect type and are fitted to smaller ships. Gravity collection reduces the plant size since flush water is minimised.
The main problem with CHT systems is their limited hold time of 5-7 days. This in turn leads to the requirement for costly sewage reception facilities in the Naval Bases and can lead to problems when ships visit or operate in clean areas.


SUMMARY OF THE INVENTION

The object of the present invention is to provide an improved sewage treatment plant, capable of operation on a mobile platform and of use for longer periods than currently available plant.
The invention provides a sewage treatment plant comprising a collection tank, a settlement tank, an aeration tank, transfer means and a transfer controller arranged such that sewage is transferred in controlled batches into the aeration tank and subsequently out after separation of solids whereby processing can be accurately controlled.
Advantageously a fresh water flush vacuum system is used to collect sewage in the collection tank. The use of a small amount of fresh water, vacuum-assisted, eliminates difficulties experienced with the use of sea water of varying salinity. The batch processing overcomes the difficulties of operating a continuous flow arrangement on a moving platform where liquid can move back and forth. Known biological settling systems operate effectively only under static conditions because of difficulties in controlling the level of biological activity. In the present invention, a controlled amount of sewage is transferred to the aeration tank via a grey water dillution system for a controlled period before separation of the solids transfer from the aeration tank.
The settlment tank is provided between the collection tank and the aeration tank whereby sludge may be removed prior to aeration treatment and dillution with the grey water.
Advantageously a sludge storage tank is provided and suspended solids density probes are provided in the aeration and settlment tanks such that sludge is automatically withdr

REFERENCES:
patent: 3355019 (1967-11-01), Mitchell
patent: 3522881 (1970-08-01), Nicol
patent: 3552554 (1971-01-01), Olgard
patent: 3679053 (1972-07-01), Koulovatos et al.
patent: 3844946 (1974-10-01), Farrell, Jr.
patent: 3920550 (1975-11-01), Farrell, Jr. et al.
patent: 3950249 (1976-04-01), Eger et al.
patent: 4009104 (1977-02-01), Behrendt et al.
patent: 4122013 (1978-10-01), Greenleaf, Jr. et al.
patent: 4211645 (1980-07-01), Zajic et al.
patent: 4622134 (1986-11-01), Kobayashi
Melcer et al, "Conversion of Small Municipal Wastewater Treatment Plants to equencing Batch Reactors", JWPCF, vol. 59, No. 2, 2/87, pp. 79-85.
Storch, "Sewage Disposal", Shipping World & Shipbuilder, 9/72, pp. 1073, 1074 and 1093.

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