Methods of removing solids from liquids

Abstract

A method of removing solid matter from liquid using two or more sets of screening devices installed in series. Each set of screening devices consists of one or more identical or nearly identical screening devices. Each downstream set of screening devices has smaller openings than the preceding upstream set of screening devices. Solid matter collected by the screening devices is automatically discharged onto two or more conveyor systems that deposit the material onto one or more central collection areas for final removal and disposal. The present invention uses screening devices in a special configuration to achieve enhanced removal of solid matter from liquid (i.e. a series installation with screen opening size decreasing in a downstream direction).

Description

FIELD OF THE INVENTION[0001]This invention relates to the field of fluid screening systems and it discloses a simple and efficient method of screening solid organic and / or inorganic matter from liquids such as, but not limited to, stormwater, wastewater, combined sewer overflow, raw water, and industrial flows.BACKGROUND OF INVENTION[0002]There is a great need to remove solid matter from flows of liquids in many applications. The United States Congress, through the Clean Water Act Legislation of 1972, began requiring municipalities to remove certain pollutants from stormwater runoff (hereinafter “stormwater” or “runoff”) before it discharges into the nation's waters. Polluting matter that must be removed from stormwater includes, but is not limited to trash and other human produced debris, leaves, tree and bush limbs, and similar pieces of vegetation; aquatic plants, such as hyacinths, water lettuce, duckweed, various grasses and weeds, etc. growing in canals and ditches, etc.[0003]...

AI Technical Summary

Problems solved by technology

The damage to the nation's waters and their ecosystems by human generated debris is easily apparent.

As the organic matter degrades in the nation's waters, it releases dissolved nutrients such as nitrogen and phosphorus that cause algae blooms that further damage the receiving water by depleting oxygen and causing fish kills and other harm.

Non-biodegradable (inorganic) matter is preferably removed from the wastewater before it enters the wastewater treatment units, because it usually cannot be degraded by biological processes and further, may damage equipment in the treatment units.

In such instances, a portion of the mixed stormwater / wastewater flow may be diverted, untreated, away from the wastewater treatment plant into a river, lake, or stream, thereby significantly polluting the nation's waters.

However, most of the prior art treatment systems are unable to remove the majority of solid matter from liquids without utilizing multiple, often complex, treatment units.

For example, solid matter may be removed down to a certain particle size by one device, but to achieve further reduction in particle size, another, often different and usually more complicated, device must be used.

For instance, a screening device followed by a complicated device such as a vortex-type removal system may be required to remove very small particles.

Further, these prior art methods and devices are often not as efficient or as cost-effective as the subject application, particularly for large flow rates.

Further, current screening technologies are usually sufficient for relatively low volume flows, but are incapable of properly screening large volume flows, such as stormwater flow rates, sufficiently to prevent overflow.

It is not designed to handle large flow rates and volumes, so it could not be placed within a channel or canal.

Until the screens have been cleaned, stormwater or other excess water flows will bypass the screens and the device will not be capable of removing additional matter.

Therefore, besides being labor intensive and thus, costly to maintain, the device may not always be capable of capturing the solid matter it is intended to remove from the liquid.

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