Dr. Ali,
Complete Package Plant
Stage 1. Chemical Conditioning
In the first stage of the package water treatment plant, the raw water is fed into a rapid mixing zone where neutralizing and coagulating chemicals are added. Coagulants neutralize the charge and promote collisions between the small suspended particulates, called colloids, enabling them to form flocs. The coagulated water enters the flocculation tank. A coagulant aid or polymer is usually added to strengthen the floc bonding. Slow stirring motion in the flocculation chamber promotes collision between the forming precipitates and the remaining contaminant particles to form larger flocs.
Stage 2. Clarification
The coagulated and flocculated water is evenly distributed across the clarifier using well designed distribution laterals under the tube settlers. Tube settlers are used to promote rapid clarification. The tube settler consists of square tubes, usually inclined at 60 degrees, which causes the “captured” floc particles to settle by gravity to the bottom of the clarifier and form sludge. The sludge accumulates in the bottom of the clarifier’s hopper and is withdrawn through a desludge valve at regular intervals. A collection system on the surface collects and directs the clarified water to the filters.
Dissolved air flotation clarifiers can also be provided for high rate clarification.
Stage 3. Filtration
Clarified water enters the high rate gravity filter for removal of the remaining finer solid particles. Based on the application, the filter media can be dual media, multi-media, GAC, greensand, or MD-80. The water passes through the layers of the media and is collected by the under drain system. This filtered water is then sent for disinfection or further processing.
Optional Ultraviolet (UV) disinfection expands the protection offered by Napier-Reid’s plants, ensuring complete inactivation of waterborne pathogens including Cryptosporidium and Giardia.
By package it might mean the equipment arrives on trucks preassembled and sufficiently complete that it can handle the required load and produce effluent acceptable to the local environment.
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