Tetra Technologies, Inc.

Tetra Process Technologies a Severn Trent Services Company

Gregory A Ellard

Joseph M Bonazza

David C Slack

Miguel J Merino

A method for controlling the addition of liquid treatment chemicals by automatic dose control. The calculation of the amount of chemical to be dosed into the system combines signals from a liquid flow meter, an influent chemical concentration analyzer and/or an effluent chemical concentration analyzer. The signals are directed to a computerized chemical dose controller that analyzes and adjusts the data from the signals and generates an output signal that controls the chemical dosing mechanisms. For example, the automatic dose control method encompasses the ability to set maximum positive and negative limits of control action as well as the ability to automatically or manually control the reset period necessary to allow previous changes to propagate through the system and be displayed at the effluent sensor thereby improving the dosing of the chemical during treatment of a liquid, wastewater for example.

Method for automotive dose control of liquid treatment chemicals

A method of degassing biological filters utilizing a backwash system wherein the steps of opening and closing valves are reduced, flow interruption through the filter is minimized, and the process of draining down a downflow filter is eliminated. A preferred method of degassing a plurality of downflow biological filters in a water treatment system comprises the steps of maintaining the influent flow throughout the degassing process, ceasing the effluent flow out of a filter selected to be degassed to prevent draining of the selected filter, introducing a backwash water flow into the bottom, and flushing of the filter until entrapped gases are released out of the filter. The backwash flow is then ceased and the effluent flow is recommenced to return the filter to service. The steps are successively repeated and the backwash pump remains on until all filters are degassed. The method of degassing a plurality of upflow biological filters comprises the steps of maintaining the effluent flow throughout the degassing of all filters, ceasing the influent flow into a bottom of a first filter to be degassed, introducing a backwash water flow into the bottom, flushing the filter until entrapped gases are released out of the filter, ceasing the backwash flow and recommencing influent flow to return it to service, and successively repeating the above steps to degas all other selected filters in the treatment system. The transition of the degassing process from one filter to another is seamless.

Method of degassing biological filters

This invention relates to a method and apparatus of denitrification. The apparatus includes a weir block, a denitrification vessel having a wall surface, and filter media having microorganisms on their surfaces. The weir block may have a convex outer surface which is tangentially adjacent to and preferably contiguous with the upper end of the wall, whose lower end is in contact with the water in the denitrification vessel. The method may include passing the wastewater over the convex surface of the weir block, passing the water over the second surface of the substantially vertical wall and into the denitrification vessel while preferably maintaining substantially laminar flow and limiting the dissolved oxygen in the denitrification vessel, preferably to below about 5 mg/L and more preferably to below about 4 mg/L.

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Tampa, FL, United States of America

Gregory A Ellard