Davis Water and Waste Industries, Inc.

Davco, LLC

H Forbes Davis

James P Harshman

David J Hunniford

Anthony J Freed, Jr

In the treatment of sewage, fresh, representative samples are continuously collected and analyzed at a number of different points in a sewage treatment reservoir. A submersible grinder pump is connected by a sample supply conduit to a continuous flow through filter, and ground sewage slurry is delivered at high velocity through the filter so that it scours the internal surfaces of the filter. The sewage slurry is continuously returned to the treatment reservoir, and filtrate continuously passes through a rotameter to a transparent sample collection reservoir. Discharge from the sample reservoir is controlled by a solenoid operated valve, and a continuous overflow waste return conduit allows return of the filtrate to the treatment reservoir if the solenoid valve is closed. A computer controls operation of the solenoid valves and one or more analyzers for analyzing filtrate qualities (such as alkalinity). The solenoid controlled valves are connected to the analyzer through a manifold.

Continuous, automated, multi-stream sample collection and analysis

Aerobic wastewater treatment processes are controlled utilizing alkalinity measurements. A base line of alkalinity is determined by measuring the alkalinity profile of the influent to the aerobic wastewater treatment process. The alkalinity of the wastewater is sensed at a number of different points in the aerobic wastewater treatment process, such as at a clarifier effluent and sludge exit, aeration zone, and aerobic digester effluent. When the sensed alkalinity at any given point is above a predetermined amount over base line alkalinity, the air supply is increased and/or the concentration of microbes and food is reduced (as by increasing the sludge withdrawal rate from a clarifier) until the sensed alkaline level is stabilized. When the sensed alkalinity is below a predetermined amount under base line, the air supply is decreased and/or the concentration of feed and microbes increased (as by reducing or terminating sludge withdrawal from a clarifier) until the sensed alkalinity level is stabilized. Anaerobic odors are eliminated, plant operation and efficiency is improved, settling is improved, there is enhanced removal from the secondary clarifier, and solids carryover is reduced increasing the quality of effluent from the clarifier.

Aerobic wastewater treatment with alkalinity control

Aerobic wastewater treatment processes are controlled utilizing alkalinity measurements. A base line of alkalinity is determined by measuring the alkalinity profile of the influent to the aerobic wastewater treatment process. The alkalinity of the wastewater is sensed at a number of different points in the aerobic wastewater treatment process, such as at a clarifier effluent and sludge exit, aeration zone, and aerobic digester effluent. When the sensed alkalinity at any given point is above a predetermined amount over base line alkalinity, the air supply is increased and/or the concentration of microbes and food is reduced (as by increasing the sludge withdrawal rate from a clarifier) until the sensed alkaline level is stablized. When the sensed alkalinity is below a predetermined amount under base line, the air supply is decreased and/or the concentration of feed and microbes increased (as by reducing or terminating sludge withdrawal from a clarifier) until the sensed alkalinity level is stabilized. Anaerobic odors are eliminated, plant operation and efficiency is improved, settling is improved, there is enhanced removal from the secondary clarifier, and solids carryover is reduced increasing the quality of effluent from the clarifier.

A modular air scrubber system is provided for removal of pollutants from air and includes a plurality of modular scrubbing towers adapted for side-by-side interconnection to provide multiple stage filtering of air to be treated, each tower having a lower reservoir portion for a scrubber solution, and an upper portion containing contact media, each modular tower also provided with air inlets outlets and scrubber solution inlets and outlets. A specific arrangement of these modules adapted to accommodate a counterflow arrangement of air and scrubber solution for the removal of hydrogen sulfide from air is disclosed, in conjunction with a scrubber solution feed and control unit.

Modular air scrubber system

Removal of dissolved hydrogen sulfide and a reduction in BOD is achieved by the addition of nitrate ions to waste systems in an amount sufficient to stimulate growth of bacteria which utilize dissolved hydrogen sulfide in their metabolism. Specifically, about 2.4 lbs. oxygen per lb. of sulfide is required.

Process for removal of dissolved hydrogen sulfide and reduction of

Process and apparatus for thickening or dewatering treated sludge in one or more thickening tanks includes the addition of nitrate ions to treated sludge as a mechanism for generating microscopic bubbles of nitrogen gas which adhere to, or are trapped by, sludge floc particles, causing a reduction in density of the particles which, in turn, causes the particles to float to the top of the thickening tank. The process separates the sludge into an upper thickened layer and a lower free water, or subnate, layer. Subnate is removed from the tank through a plurality of outlets arranged at different depths within the tank. The subnate outlets are shut off sequentially, from the highest to the lowest, as the level in the tank drops. Thereafer, the thickened sludge is removed from the bottom of the tank and pumped to a sludge disposal location. A portion of the thickened sludge may be recirculated to insure flow uniformity.

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Tallevast, FL, United States of America

H Forbes Davis