wastewater treatment plant specification...

Appendix L

Wastewater Treatment Plant

Specification Sheet

Compagnie Sucrière de Bel Ombre Ltée Second Golf Course at Bel Ombre

Environmental Impact Assessment

CSBOL/EIA/01 | Issue | 5 October 2016

J:\CURRENT PROJECT\250379-00 - EIA 2ND GOLF COURSE AT BEL OMBRE\4.5 - REPORTS AND MEMOS\INFRA\BEL OMBRE GOLF EIA REPORT (ISSUE, 2016-09-30)\BEL

OMBRE GOLF EIA REPORT (ISSUE, 2016-10-05).DOCX

Page L1

L1 Wastewater Treatment Plant Specification

Sheet

This appendix contains the wastewater treatment plant specification sheet as

provided by Solutions Eau et Environnement Ltée, SEE.

Solutions Eau et Environnement Ltée - The Junction Business Hub - Calebasses - Mauritius

Tél : +230 243 18 20 – Fax : +230 243 12 20 - Mail : [email protected] - Web : www.see.mu – BRN : C12107657 - VAT : 27129077

WASTE WATER

TREATMENT PLANT

BEL OMBRE

GOLF CLUB HOUSE

SEE 2016-09-08

22 September 2016

COMPACT WASTE WATER TREATMENT PLANT

BEL OMBRE GOLF CLUB HOUSE

SEE 2016-09-08 22 September 2016

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1. PRESENTATION

The project consists in the construction of wastewater treatment plant for Golf CLUB

HOUSE in BEL OMBRE.

The technical solution proposed is very well-adapted for small and medium water treatment

plant reaching an outlet water quality in accordance with the Mauritian and European reject

standards.

Many installations are already in service in Mauritius with this technology, which have been

controlled and validated by the Wastewater Management Authority.

For your perusal, following clients have already chosen the proposed technology:

- Medine Student Flats

- Decocity Bagatelle

- Choisy-Les-Bains

- Residential complexes developed by 2Tribes/2Future: Cape Bay, Element Bay,

The Residence, Element Bay 2

- Be Cosy Hotel / Terrasses du Barachois Residence / RES Trinidad (Trimetys)

- RES La Tourelle de Tamarin (Bhunjun group)

- Shopping Center Le Barachois in Tamarin (Trimetys)

- Shopping Center Riverside in Rivière-du-Rempart (IOREC)

- Les Jardins de Chantenay elderly house (Ideco)

- Residences Cap Ouest and Latitude (DLB Construction)

- IRS Matala in Black River

- Residence Rose des Sables (Davyland)

- And many others independant promoters/developers

These references show that it is a very well adapted and efficient solution and also cost

effective.



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Underground STP in Bain-Boeuf

Underground STP in Black River



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Underground STP in Wolmar

Underground STP in Flic en Flac



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2. TREATED WATER OBJECTIVES

Objectives for treated water are the Mauritius Irrigation Standards:

Main parameters are:

Parameters Outlet value

BOD5 ≤ 40 mg/l

COD ≤ 120 mg/l

SS ≤ 45 mg/l

Fecal Coliforms ≤ 200/100ml

- On a 24h composite sample.

- For a temperature ≥ 12°C and ≤ 30 °C and pH between 6 and 8.5.

- And as long as the above mentioned wastewater characteristics are respected.

Treated water quality



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3. TECHNICAL SOLUTION

3.1. THE CONTEXT

The project consists in the construction of a wastewater treatment plant for daily volume of

12m3 of wastewater.

Effluent characteristics:


Hydraulic loads

Daily volume Vd m3/d 12.0

Average daily waterflow m3/h 0.8

Peak flow coefficient 3.0

Peak waterflow m3/h 2.3

Pollution loads

BOD5 kg/d 4.2

COD kg/d 8.4

TSS kg/d 5.4

TKN kg/d 0.6

Oil, Grease and Fat kg/d 0.1



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Specificities of the treatment plant:

The plant will treat wastewater coming from the project.

Hydraulic and pollution loads will fluctuate according to the occupancy.

The wastewater treatment plant must be adaptable to these variations all other

the year.

As the plant is installed near the habitations, it has to be fully integrated site wise

regarding visual, noise and odour aspects.

Available area is limited: the plant has to be compact and easy to install.

Treated water quality has to be fully in compliance with the environmental

standards 365 days/year.

3.2. SOLUTION PROPOSED

The water treatment technology proposed is a different solution based on aerobic biological

treatment on fixed immerged support.

The bacteria fixed on an immerged support will promote the biological oxidation of the

wastewaters. Active air incorporation into the system allows bacteria to grow.

The advantage of this technology is the complete control of the treatment, guarantying the

water outlet quality in all circumstances.



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CHARACTERISTICS SOLUTION PROPOSED

Adaptation to different

pollution concentration

The « fixed bacteria » technique is the only technique allowing an easy

adaptation to pollution peaks and variable pollution concentration in waters,

guarantying a good usage of the treatment plant throughout the year.

Reject quality Irrigation reuse with a tertiary step of treatment

Process evolution and

extension

Compact and adjustable, the process is easily extensible by adding a compact

module in parallel

Site integration Compact and invisible : can be adapted in various environment

Installation Simple and quick installation

Site topography In major case, a few centimeters slope is enough and the system does not need

any lifting station

Fiability Process and equipment control



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3.3. PRINCIPLE

The water treatment technology is a different solution based on aerobic biological treatment

on fixed support.

Autonomous and semi collective water treatment plants have to deal with regular pollution

concentration changes:

“Tub effect” (rapid « tub » emptying)

Low usage periods

It is therefore important that the bacteria responsible for the water treatment are present within

the system in all circumstances: it is the reason why fixing the bacteria is a key principle in

this system.

In the aerobic system, the bacteria will grow in presence of air on a specific support.

The support has been designed to optimize bacteria activity.



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3.4. FUNCTIONNING

The treatment takes place in 3 phases, requiering 3 cells:

CELL A : PRIMARY CLARIFIER

A: Polluted water is received in the first cell called primary decanter. The suspended

materials will decant in the lower part of the cell and will be “pretreated” by anaerobic

bacterias (bacteria which do not need air). Through this first anaerobic bacterial

action, most solid materials will be liquefied.



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CELL B: BIOLOGICAL REACTOR

B: Pre-treated water flows by gravity into Cell B « Biological reactor ». In this tank,

pollution matters will be eliminated by aerobic bacteria.

E: Organism and bacteria of the biological reactor fix and grow on an immerged

polypropylene support. This support is constructed with recycled polypropylene, in a

sustainable development concept. Its shape allows an optimal development and growth

of bacteria, resulting in optimal conditions for elimination of pollution matters never

reach in that kind of small wastewater treatment plants.

D: Air blower diffuses oxygen for aerobic bacteria which grow on surface of the

immerged support.

F: Air is diffused at the bottom of the tank via fine air bubbles diffusers.



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CELL C: CLARIFIER

C: Water enters in third tank (clarifier) by gravity. Aerobic bacteria which are

eliminated pollution matters become in suspension and are able to settle. In the

clarifier, bacteria (called sludge) and treated water are separated. Treated water is able

to flow to the outlet directly to reject point and be reused in irrigation.

H Sludge settles to the conic bottom of clarifier.

G: Sludge is evacuated by pumping and re-circulated into Cell A (primary clarifier).

There, it is mixed with primary settled sludge and partially digested with time.



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3.5. INDICATIVE DIMENSIONAL CHARACTERISTICS

Plant can be installed totally below ground level.

Dimensional characteristics are:

Golf Club House

Dimensions

Dimensions L (m) w (m) H (m)

Primary settling tank 2.2 1.8 2.8

Aeration tank 3.0 1.8 2.8

Clarifier 2.0 1.8 2.8

Pre-filtration 0.4 1.8 2.8

Irrigation storage tank 3.4 1.8 2.8

A technical room of 3 x 2 m will have to be built for filtration / disinfection unit and electrical

board.

All tanks will be made with concrete on site and are excluded of our scope of works.

Tertiary step of treatment (filtration and disinfection) for re-use in irrigation is described

below

A grease trap (not included) must be built upstream of the STP.

Treated water storage tank can be connected to rain water network.



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4. COMPONENTS DETAILS

4.1. AIR PIPES AND MANIFOLD SYSTEM

Air pipes and manifold system are made with PVC pressure pipes PN16 according to the

standards NBN EN 1452. Components assembly is performed by gluing. Air pipes are fixed

to the concrete side walls with synthetic corrosion-proof clamps.

4.2. AIR DIFFUSERS

Aeration tank is equipped with «fine bubbles» diffusers which ensure proper aeration and

mixing.

4.3. BLOWER

One air blower will be supplied and placed in a correctly ventilated machine room. This

machine room will be able to host the blower and the instrument control cabinet.



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The blower will be equipped with a sound enclosure to protect the machine and to decrease

the sound level pressure with insulated pipes. The blower is provided with the following

fittings:

Inlet filter

Oil level control

Filter pressure differential gauge

Sound enclosure

Check valve

Safety valve

4.4. SLUDGE RECIRCULATION

One submersible pump will be installed.

Manufacturer KSB or similar

Number 1

Head 6 m

4.5. BIOFILM CARRIER

Biofilm carriers (packing medium) are easily removed from the tank to allow anytime a

maintenance work in the biological reactor.



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Biofilm carrier specifications

Material Recycled polyethylene/polypropylene

Shape Polygonal

Void percentage +/- 90 %

Volume weight +/- 105 kg/m³

Specific surface

area +/- 195 m²/m³

Packaging +/- 85 L rot proof bags

4.6. FILTRATION AND DISINFECTION

In order to re-use the treated water for irrigation, it is necessary to install a tertiary step of

treatment.

It will be composed of 1 filtration pump, 1 sand filter and 1 chlorination dosing pump.

Submersible Filtration pump:

Manufacturer KSB or similar

Type Amaporter

Number 1

Flowrate 5 m3/h

Sand filter:

Manufacturer ASTRAL POOL or similar

Type CANTABRIC or JUPITER

Number 1

Diameter 600 mm



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Example of sand filtration unit

Chlorination dosing pumps:

Manufacturer ASTRAL POOL or similar

Number 1

Flowrate 1 - 10 l/h

Pressure 2-4 bars

Example of chlorination dosing pump



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4.7. CONTROL PANEL

The control panel is equipped with circuit breakers, protections, motor starters and 2 signal

lamps.

Example of control panel

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