WASTEWATER TREATMENT SYSTEM ENGINEER'S REPORT
New Harbour Village Housing Development Old Harbour
APPROPRIATE TECHNOLOGIES LIMITED 5 Avesbury Ave.,
Table of Contents Section 1: General Project Information
Section 2: Sewage treatment System and Appurtenances
Treatment Method Technical Description Lakeside Advantages Basis of Design Anticipated Effluent Quality CLR Process Modes
CLR Process Reactor Design Oxygen Requirements Mixing Requirements Final Clarification
Additional Treatment system designs
Sludge Management System Chlorine Contact Chamber V-notch weir Effluent Discharge Section 3: Design Calculations
Lakeside CLR Process Calculations Lakeside Spiraflo Calculations Additional treatment system designs
Grit/trash chamber design Sludge digester design Chlorine Contact Chamber design V-notch weir designs
Section 4: Operations and Maintenance Manual Section 5: Drawings Reference Appendix
General project information
General Project Information
The proposed domestic sewage treatment plant is designed for New Harbour Village, a proposed housing development in the Old Harbour area of St. Catherine. The housing development will consist of approximately 950 2 bedroom houses. The systems capacity is designed for 0.361M gallons of sewage per day. The treatment plant is designed by Appropriate Technologies Ltd. utilizing Lakeside Electro/Mechanical Equipment. The characteristics of the wastewater influent and the expected effluent characteristics are outlined in the Basis of Design
Site Topography The general character of the land in this rural area is generally uniform with
less than 10% of the proposed site being on a slope. The predominant soil type on the project site is upland plateau soil with bedrock outcroppings. Based on a soils investigation report completed through to a depth of 3m below existing ground elevation, the strata is dense cream brown limestone with sand and silt (see appendix for Bore hole logs) The project site is located in a coastal zone and situated above the 10 m contour line. There are no water wells adjacent to the site as well as there are no sink hole conditions.
Sewage treatment System and Appurtenances
Sewage Treatment System and Appurtenances
Plant Site The plant site will be located in a remote area 40m (130 feet) away from the
subdivision boundary and more than 40m away from the Parochial road. The site will be fenced to ensure security from vandalism as well as ensuring that humans as well as animals do not accidentally just wander onto the site. The sewage released from each house in the subdivision will be pumped from lift stations to the main sewer line. This main sewer line will empty the sewage by gravity directly into the treatment plant.
The surrounding areas of the plant site are rural lands comprising generally of trees and shrubs. See Appendix for a plan of the plant site location.
Treatment Method Technical Description Combined biological nitrogen and phosphorous removal can be achieved with CLR Process with the addition of an anaerobic and anoxic stage ahead of the aeration basin. It combines BOD5 removal with de-nitrification and phosphorous removal. The plant will be designed to produce tertiary treated effluent that will meet NEPA Irrigation Standards. The proposed system includes an anaerobic inlet chamber with two anoxic chambers followed by two aeration basins and two clarifiers. A sludge digester and a bank of drying bed will also be included as part of the system, to allow for easier sludge management during the operation of the plant. Our system will have eight basic components: - ??A Grit/Trash Chamber
??An Anaerobic Chamber ??Two (2) Anoxic Chambers
??Two (2) Closed Loop Reactors (Oxidation Ditches) ??Two (2) Spiraflo Clarifiers ??A Chlorine Contact Chamber ??A Digester ??Two (2) Drying Beds
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Lakeside first introduced the "oxidation ditch process" to the United States in 1964. Since that time this simple activated sludge process has evolved to what is now known as the state-of-the-art Lakeside Closed Loop Reactor (CLR) Process. To date Lakeside has installed more than 1,700 CLR Process installations worldwide.
The Lakeside "experience factor" is more than 5 times our nearest competitors which introduced their versions of the "oxidation ditch" process only 5 years later than Lakeside. Why has the Lakeside CLR Process been preferred by engineers and owners? Please consider the following advantages for both process simplicity, process flexibility, superior equipment design and ease of maintenance and low cost.
Lakeside offers the following benefits to the owner and engineer from project inception, through design, start-up and operation:
NO LICENSE FEES - are charged by Lakeside to provide up-front profits for our equipment.
Specifications and drawings along with process design assistance are offered as part of normal business
FUTURE EXPANSION - considerations are designed by the Lakeside professional staff into each CLR
Process to allow not only additional treatment capability but also to respond to changing effluent limitations
such as Biological Nutrient Removal (BNR) with our non-proprietary processes which do not require expensive license fees nor will additional reactors be required for future Total Nitrogen removal.
FLEXIBLE OXYGEN DELIVERY - is provided by the Lakeside Magna Rotors. Each Magna Rotor with
a simple 2-speed drive has an Oxygen Delivery Ratio (ODR) of 6.87 to 1 when operating at immersion
ranges of 5 to 15 inches and rotational speeds of 48 to 72 rev/min. This means greater process control for
BNR and associated energy savings, especially during the initial start-up year conditions.
MIXING UNDER ALL FLOW CONDITIONS - is provided with our design to ensure a bulk liquid velocity of 1 ft/sec or greater, even at low power input. The power necessary to maintain a 1 ft/sec minimum bulk liquid velocity in each reactor is only 7.2 brake horsepower. Compare the power necessary
to maintain a similar 1ft/sec minimum bulk liquid velocity with other types of aerators such as vertical
MADE IN THE U.S.A. - defines the Lakeside CLR Process equipment. All our CLR Process equipment is fabricated at our shop in Chariton, Iowa. Buy-out items such as motors, speed reducers, bearings, etc. are standard stock, off-the-shelf components for overnight delivery should a replacement ever be needed. This is not possible with the drive used by vertical turbine aerators.
SOURCE: EPA 832-R-92-001 (Sept 1992)
EIMCO Carrousel (1968)
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BASIS OF DESIGN
This design was selected based upon the following criteria (US units):
INFLUENT DESIGN PARAMETERS Average Day Flow, mgd
Peak Day Flow, mgd
Peak Hourly Flow, mgd
BOD5 , mg/l
INFLUENT DESIGN PARAMETERS
Total P, mg/l
Minimum Temperature, oC
Maximum Temperature, oC
Site Elevation, feet above MSL
PREDICTED EFFLUENT CHARACTERISTICS CBOD5 , mg/l
Total P, mg/l
CLR PROCESS BNR OPERATIONAL MODES
Most small facilities are designed with chemical addition since the time/education/experience of the operations staff is not conducive to their ability to controlling the process for biological phosphorus removal. Chemical addition to the final clarifiers for phosphorus precipitation has been successfully implemented on numerous applications. The Lakeside Spiraflo Clarifier is especially well-suited for chemical precipitation of phosphorus. Refer to Plant Performance Report 126 Bemidji, MN.
- 4 - The Phoredox configuration is the simplest design for strictly pass through operation. The Phoredox design variant does not require extensive instrumentation and control.
Lakeside has furnished equipment for similar facilities for Snow Hill, North Carolina, Becker, MN, Alberville,
MN, Prescott Valley, AZ and many other projects. Refer also to Plant Performance Report Nos. PPR-131a and
PPR-131b on our project for Prescott Valley, AZ and PPR-134 on our project for Becker, MN. Refer to the
CLR PROCESS STANDARD OPERATIONAL MODES
To provide maximum operator flexibility and ease of operation, we can design the aeration basins to be operated
in parallel, series, or in a "peak flow" mode. Bulletin 1412, CLR Process Modifications Section, provides an
excellent discussion of the various standard process options that are available. To provide maximum operator
flexibility and ease of operation, we design the anaerobic, anoxic and aerobic reactors to be operated in parallel
or series using common wall construction to save concrete and piping costs. This flexible control can be
provided by a utilizing a series