824 ZADU99

water

DURBAN WATER RECYCLING PROJECT

libraryIRC International Waterand sanitation CentreTel •'i-31 70 30 689 80Fax: +31 70 35 899 64

DURBAN WATER RECYCLING

E(fluem. Pollutants sewage Probably not one of(lie most sought after topics for after dinner

conversation, yet the subject of one of the mostimaginative industrial deals put together in trie history

- of South Africa.

Durban recently witnessed the signing ofa 20 year concession contract betweenDurban Metro and Durban water RecyclingIDWRI. DWR has been formed by aconsortium of local and internationalcompanies and includesOTV as a major stakeholder. OTVSimply put. the deal which is a public/private

partnership allows the construction and operation ofa new waste water purification plant that willtreat domestic effluent supplied by Durban Metro, to

¡A

••• 1

$£

i • • ••

J . •

• • • - •

! •

%

3S I i^^IS? i ^w

a!..sãla» #

No longera dirty word.

an acceptable standard tor industrial use. The recycledwater will then be purchased by local industry within

the Durban area. Currentprojections indicate that thenew plant will be able to

process in excess of 47 000 cubic metresof treated water per day.

Apart from the financial investment andthe incorporation of world classtechnology into the new plant, majorbenefits will include a reduction in theoverall industrial consumption of potable

water and a decrease in the amount oftreated sewage being released into theenvironment, industry will also gain, ascheaper water will allow a significantreduction in local costs.

Since the announcement of the contractby DWR. several more of Durban Metros industrialclients have expressed an interest in participatingin the project, which mey lead to a farther increasein the demand for recycled water

Which just goes to show that with some ingenuity,vision and hard work, even the most unpleasant ofsubjects can be given a fresh perspective.

DWRDurban Water Recycling (Ply) Ltd. Tel: (031) 462-2598

Fax: (031) 469-0961 E. Mail: omarche<§dwr.co.za

DURBAN PROJECT water.

DURBAN METRO

Conce;sion Agreement

Durban Water Recycling (Pty) Ltd51% OTV France18.5% Umgeni18.5% Khulani10% Marubeni2% Zetachem

Development Bank \ Loanof Southern Africa \ Agreements

2 Off-shore Construct!On-shore Construction Contract

WaterSupplyAgreements Clients:

MONDI (Paper Industry)

SAPREF (Refinery)

peration-Maintenancentract

OM/ 00/02/18

VTVENDIwater

DURBAN WATER RECYCLING PROJECT

A WIN-WIN PROJECT

Environment

Durban Metro

Reduce pollution rejected to the ocean

Save raw water used to produce potable water

Potable water immediately available for domestic use

(townships)

Delay new investment in potable water production works

Financial

Industrial customers : • Major savings on their process water expenditure

(approximately 30%)

Close co-operation with water treatment specialists

Vivendi Water First project in South Africa

Perfect reference

Financial

VÍVENDIwater

DURBAN WATER RECYCLING PROJECT

FINANCING

Project value : R74 million (Euro 11,3 million)

Equity from DWR shareholders : R14 million (Euro 2,3 million)

Development Bank of Southern Africa : R18 million (Euro 2,8 million)

Rand Merchant Bank : R24 million (Euro 3,9 million)

French Protocol : Euro 2,3 million

VÍVENDIwater

DURBAN WATER RECYCLING PROJECT

WATER QUANTITY

Production Capacity : 47 500 rrvVday

Mondi (Paper Industry) consumption : 30 000 to 39 000 nWday

SAPREF (Refinery) consumption ; 3 300 to 8 900 m3/day

From pritnaiysed. tanks

49.5 Ml/d

i

Activated sludge

49.5 Ml/d 99.0 ML/d

FLOW DIAGRAM FOR 47 500 m3/d OF RECLAIMED WATER

0.8 Ml/d- ForDMWWM

1Internal use

DWR

Filtered watertank for

backwash

ni—..

H0.6 Ml/d- T

-0.2 Ml/d-

-47.6 Ml/d 47.6 Ml/d-

10.1 Ml/d

1.2 Ml/d-

6ACContactor

-47.5 Ml/d- Chlori nation

0.3 Ml/d47.2 Ml/d

¿re^"-=.' \

1.0 Ml/d

I

Reclaimed watersold to industrials

2.0 ML. d sludge to deep seaoutfall

Unique concession will see massivesewage re-use in Durban

A world first was recently achieved, with the signing of a contract between Durban Waterand Waste and a consortium consisting of international and local companies. The 20-ycarconcession contract will sec the construction and operation of a new wastew ater purifica-

tion plant that will treat raw domestic sewage to an acceptable standard for industrial use.The plant will result in numerous advantages for the local authority, for industry and forthe community of Durban, and will hopefully pave the way for other local authorities to

engage in meaningful projects with the private sector.

I cil Macleod, executive director(water services) of Durban MetroWater Services told IMIESA in

an exclusive interview thai the munici-pality pursued the concept, of sewage re-use as a result of industry concern overrising water price.The local authority began to researchways in which ¡L could reduce the cost ofwater to industry. Its research culminatedin a pilot project that was recorded in apaper presented at the 1996 WaterInstitute of Southern Africa conference.

The city council could technicallyproduce purified water from domesticcfllucnt, but funding was the over-ridingbarrier to yelling the project off theground. Determined that the metro wasonto a good thing, Macleod and his teaminvestigated the option ofengaging the private sectorin a public private part-nership (PPP).

"We discussed theconcept with our counciland with 'labour1. Ourarguments for a PPP werebased on the fact thattreating sewage for indus-trial re-use is not a corefunction ol" the localauthority and should thusbe out-soureed. We weregiven council blessing. Theunions too agreed to theconcept of a PPP, but withthe proviso that councilstall would know exactlyhow to run the plant inthe event that the privatesector abandoned ship,"Macleod explained.

Water and Sanitation Services SA,Biwatcr, SAUR and OTV went onto thenext round with final tender documentsin hand. SAUR withdrew from die tenderprocess leaving the council with threebids to adjudicate.

The remaining contenders were askedto comply with various criteria such as thesoft issues: local content, affirmativeaction and training etc. Secondly, a graphwas devised on which to adjudicatetenders whereby the quoted prices andproposed volumes of treated sewage wereplotted. Each company was awardedpoints accordingly. The candidates had toadditionally comply with a treatmentstandard and identify the clients to whichdie final product would be sold.

"We made it dear from the beginning

(Left to right): Kevin McNally, Neil Macloed and C. Mavet, vice-presidentInternational BOTA Projects of OTV (Standing) N Theunissen, legal

council (Shepstone & Wylie) - at the signing ceremony of the Durbanconcession contract

Pre-qualif ¡cationWith the support ol us necessary stake-holders, Durban Metro called for thesubmission of prc-qtialiliaction documents.Macleod said ihat 18 submissions werereceived and that the nietro narrowed itschoice down to lour companies. Theunsuccsslul companies had access to infor-mation as to why they did not prcqualily.

that we were prepared to enter intonegotiations. We thus questioned eachbidder as to which issues they wanted tonegotiate and we discussed any ambigui-ties in their bids. Our final decision wasbased on compliances with the soft issues,the highest score on the graph and theorganisation that wanted to make theleast changes to our proposed contract.

That was the OTV-lcd consortium thathas since been named Durban WaterRecycling (Pty) Ltd.

The two unsuccssful tendcrsers weresent a detailed analysis of their bidsdescribing why they had not been thepreferred bidders.

Durban Metro Water Services thenentered into a four-month negotiationwith die OTV-lcd consortium, and finallysigned die contract in December 1998.

The termination clause was specificallyrenegotiated, as this had been the clausethat all three bidders wanted to change.

Design phaseDWR has thus now entered into thedesign phase for the construction of anestimated R70-million treatment plant

and a RIS-million refinanc-ing of an existing DurbanMetro Water Services plantthat will be integrated intothe final plant. The newplant will initially treat 42,75 M¿ a day of raw dom-estic sew age supplied by themetro.

The plant is expected tobe operational in around ISmonths. It will treat a totalof 10% of the metro'ssewage and reduce thedemand for potable waterby eight percent.

DWR will pay DurbanMetro Water Services anannual management Ice anda fee for the lease of theland on which the plant isto be constructed. A furtherlevy of R0, 24/m ; ! will bepaid to the council for the

20 year period of die concession, as thecouncil will lose its cross subsidisationincome from the participating industries.

The initial cost per cubic metre toindustry will be R l , 65 a reduction of R0,SS on the current price industry is payingfor potable water in the Durban area.

"This contract has brought manyadvantages to our area of jurisdiction.

Imiesa Februarie 1999

Treating 42 m¿ of rawsewage for industryuse1 he following is i !)ii(( ilcscripiiipiif>! tile prop'tM.fi !iv.ilm<:l11 pruossloi i he new tvoikAlttom.dt. (i i i i l iui.nl flow r.iti-

I'nm.ii'. setriln^ i>v fiiirlMli Mi'lm

Acr.moi1 i''.-$;iilwliii:¡ suppieinenicu•viili • fvva.cn

SI;Í"!J11<1 .'I'1.' ci.illtit-.ilirii!

4,Kii.ll;' i: it1 !J!ii>'i

!'!•( aitjiistmi.ii! .vnh Ci )i

( in tun: i'o.if;ul.ii'ir>n .íiul llocctilaiion

DIM! 'liedi.! liiu in>ii '.uilltiacire .¡iif.iSJIKl :

Ozoiution

CtA<. tihration

Chioniiniion

Apart from new financial investment andworld-class technology, we will berecycling clliucnt. This in Uim reduces thedemand lor potable water, and reduces thequantity ol' diluent we pur hack into theenvironment. Industry will reduce theircosts by accessing less expensive water."

Other areasSince the announcement o f the contract:,several of Durban Metro's industrial clientshave expressed an interest in the project.Maclcod said lilis might well lead to anincrease in demand lor recycled water.

"We would thus have to investigatethe possibi l i ty ol "d i rec t ing domesticsewage from other arcas lo the new plant.This would extend the fniai ici. i l andenvironmental advantages ol sewage re-use to other areas."

The concept of a concession contractsolving financial constraints o f localgovernment has been debated widely inSouth Africa. Other I ' l ' I ' contracts in thewater and vv.istcwaier Melds are currentlyunder negotiat ions. These have beensubject to delays and complications.

Mnc ieod said that the biggeststumbling block to concession contractsis Section 10 ol the Local GovernmentTransit ion Aci that stales that .1 localauthority may not enter into a concessionwhere the private sector collects therevenue. Our contract is not iimiied bythis clause as DW'R is not going 10 be

NEl/T

collecting die revenue for a service whichDurban metro would normally provide,nor will it be collecting any revenue thatis due to the council. DVVR wil l beproviding a service to a client using a rawmaterial that Durban Metro WaterSen ices provides 1'rec or*charge."

In Mnclcod's opinion other concessioncontracts in this industry will continue tobe hampered unless the contracts can bereformulated or the Department ofConstitutional Development revisitsSection 10.

He however said that this should notput local authorities olí, and offered anyadvice regarding this unique concessionto his colleagues 111 other city councils.

Extremely enthusiasticOn contacting Brian Walford, chiefexecutive of Umgcni Water for hiscomments on the project, he wasextremely enthusiastic and commendedDurban Metro for its decision to proceed.

"Umgcni Water through its commer-cial subsidiary Umgcni Water Services,was very pleased to become involved inthis exciting and innovative project.Although the recycling of wastewatcr willin the short term negatively impact onour sales of water to Durban Metro, inthe longer term it will defer major capitalexpenditure that would have been neces-sary to extend our infrastructure to meetwater demands.

From a water conservation andenvironmental management point ofview, this project is one that we felt wereally must support and I believe that thiswill be the start of many similar projectselsewhere in southern Africa.

Vast advantagesCommenting on the 20-ycar Durbanconcession, Durban Water Recyclingchairman, Kevin McNally told IMIESAthat the project has vast environmental,technological and enconomical advan-tages for Durban and for the country.

"Expanding on the environmentaladvantages thai Macleod and Walfordhave highlighted, I would like to add thatthe project; will enable the participatingindustries (Mondi, SAPREF and Sasol) tocomply with international and localenvironmental requirements. This isparticularly true for Mondi, which willreceive 30 000 m-'/day from the new-plant. As Mondi exports a great deal of itsproduct, it will be in a position to tradeon the environmental benefit resultingfrom wastcwatcr re-usc," McNally said.

He commented that the project willbring international technology and exper-tise j.nó that a valuable skills transfer willtake place.

"L-'rom the investors' point of view, theeconomics of this project arc sound andthe return on their investment will be

good. In addit ion, the project hasbrought direct foreign investment ro diecountry to the tune of around R20-million. The French (OTVi have furtherunderwritten the project by more than50%," MeNaJly added.

There is additionally an economicadvantage for the participating industries.He said the lower water cost will enablethe three companies to be more competi-tive, and if they arc more competitive ithelps the overall South African economy."There will be vast exponential benefitsall round from this project, which will becompounded if other local authoritiestake tins route."

Who is in theconsortium?Durban Water Recycling ¡Pry) Ltd isa consortium of the following compa-nies:• Zetachem• Umgeni Water Services• Khulaiii Corporate Services i I'ty 1

Ltd• Celtic Holdings (US) Inc.• O TV (a subsidiary of Coinpanie

Genérale des Eaux^• Marubeni (A Japanese Investment

Consortium)

McNally commented that the DurbanMetro concession was pushed through inrecord time (around 10 months). Heexplained that this was possible becauseof the highly professional Durban Metroteam. ''Although the negotiations weretough, they were always fair."

He said the customers were also repre-sented by professional teams around dienegotiating table, which again helpedspeed up the process.

"Furthermore, the members of theconsortium are all highly regarded andhave each played a vital and significamrote in getting this contract off theground. In particular, our empowermentshareholders have and will continue tomake meaninful contributions to thishistoric project."

The consortium's commitment toempowerment will go well beyond itsshareholders. McNally explained that ithas been decided to select three individ-uals from the previously disadvaniagcdcommunities bordering the plant site lorthe D W l l bursary programme. Thecandidates will be able to undertakestudies in the various disciplines of theplant. They will also be given extensivetraining on the Durban plant and otherOTV applications around the world.

IMIESA mill publish a derailedon the tcchmcnl aspects of the plant as soonns more information is nvnilnbk. •

Imiesa February 1999

COVER STORY

How sewagemil be re-used

111DurbanIMIESA reported in the February issue that a world first was achieved with the signing of a contract betweenDurban Water and Waste and a consortium consisting of international and local companies. The 20-year concessioncontract will see the construction and operation of a new wastewater purification plant that will treat raw domesticsewage to an acceptable standard for industrial use. In this cover story the newly formed consortium, Durban WaterRecycling, reports on the process that will be used in the plant.

Process descriptionGeneralThe Process consists of using domestic rawsewage from the Umlaas trunk main and in-dustrial raw sewage from the Jacobs trunkmain currently discharging into the Durbancouncil's Southern Wastewater TreatmentWorks and treating it to achieve high gradereclaimed water. Reclaimed water is then dis-tributed to various customers, which will in-clude Mondi, Sapref, and possibly other in-dustries like Sasol Fibers.

The works will consist of modifying ex-isting assets (mainly the existing secondarytreatment works) and building new assets(Jacob feed pump at the head of the works,new meters, autosamplers, a tertiary treatmentplant, and a reclaimed water reticulation sys-tem).The design has been based on:

• Feed water characterisation• Definition of customers demand• Hydraulic co-modelling of feed water

availability, customers consumption pat-terns, and hydraulic buffering by the on-line High Level Storage Tank (21 000mJ)

• Water treatment engineering for the defi-nition of the treatment steps

• Hydraulic modelling of the reticulationsystem

Reliability, compactness, cost-efficiency,and safety have been emphasised. In addi-tion lo designing to today's state-of-the-art

practices OTV (the consortium leader) also back up potable water connection to the re-included reliability of supply to the custom- ticulation system via the High Level Storageers as its main priority. Tank (HLST).

Built-in redundancy between consecutive The proposed plant will include for thetreatment steps has been included as well as a most part the best available technologies in

Overall treatment approach

proposed treatment process and effect on main design parameters of;i- S ¿ M ~""~*

Automated influent Htiw rate management ^ Optnni/L-Jacob's input

I Primai-y Settling by Durban Metro tjfa, - ^ Reach feed water baseline quality

: m_• ; Improve nitrificaiion/denitrification

Aeration regulation (infrastructure MMC,PLC, SCADA provided lo installpure oxygen diffusion)

(ppscwçr y\''.'..irSecondary Clarification

! Balancing Tanks (filling/emptying).•*?::-vr-.'-— • •-•

" Lamella settlerr."v»" "

,.J ->

1 pH Adjustment with CO ^ ^

On-line coagulation and flocculation - V

Dual Media Filtration (anthracite and sand)

- ^ ' 4thSecondaryClarifiergreailyrcduceschances of sludge carry-over

Reduces diurnal flow variation onto tertiary treatment plant

Reduces turbidity, suspended solids, hardness,conductivity, total dissolved solids, nieláis.

Restores neutral pH with limitedadded conductivity

Flocculation of colloids, meluls. organic matter.Careful choice of coagulant (PAC)to limit conductivity

* Ozonalion

| GACComaci/Filtraiion

I Chloiiiuuion

Removal of colloids, organic matterwith dual filtration cycle

Removal of COD and colou

Removal of residual COD

Disinfection, . • • - ; * *

f

IMIESA MAY 1999

COVER STORY

• • » •

order to attain the treatment objectives ofthe plant. The only exception will be thedown-scaling of desalination technology,which is clearly incompatible with the tar-geted water prices to guarantee thesustainubility of the project.

Individual treatmentsteps1 Jacobs sewage pumping station

Feed water onto the reclaimed water worksis primarily made of domestic Umlaas sew-age. However, industrial Jacobs sewage in-put will be required at times of low Umlaasavailability. To guarantee the precision ofJacobs sewage input, a pumping station, witha total capacity of 400 m7h, will be installedwith an electromagnetic flow meter.

Conductivity of the Jacobs sewage and pri-mary effluent is continuously monitored andpumping temporarily interrupted when theeffluent quality degrades below Base LineQuality.

The pumped quantity of Jacobs sewerageis registered and pumping may also be stoppedshould the daily maximum volume be ex-ceeded. This theoretical volume is determinedby the SCADA, based on the accumulatedprimary effluent flow that has entered the aera-tion tanks at the time.2 Secondary treatment

After testing of the existing secondarytreatment works, the following conclusions

were derived for the future process:- The COD, suspended solids and nitro-

gen removal efficiencies observed are suffi-cient to allow further treatment in the tertiarytreatment plant.

- A fourth clarifier of the same internal di-ameter as the existing three clarifiers (32,4 mwall-to-wall) will allow for the operation ofthe secondary treatment plant at 50 M#d ca-

Cokmks (Fnscij •v ******* I " •

pacity with peak flows of 77,4 Mtfd.- The existing twelve surface aerators are

able to introduce 992 kg O7h into mixed li-quor during peak flow period.

- The pH of the primary effluent is con-tinuously monitored to prevent acidic efflu-ent to enter the aeration tanks. Upon detec-tion of a pH < 4,0 the existing motorisedpenstock closes and by-passes the effluent.3 Tertiary treatment3.1 Clarified effluent pump station /balancing tanks

A clarified effluent pumping station willbe installed to feed the tertiary treatment. Oneof the duty pumps operates at a fixed speedwhile the second duty pump has variablespeed in order to match the varying flow ratesfrom the clarifiers.

Existing balancing tanks (total capacity of8 000 m-') will be used to store clarified wa-ter during the peak flow hours of the day.This stored water will be used to feed thetertiary treatment during the low flow hours.

Chlorine may be dosed to the clarified wa-ter prior to temporary storage in the balanc-ing tanks. The dose will be up to 5 mg/£Cl,and can be varied according to the actual chlo-rine demand. The existing chlorine residualmonitor will be used for this purpose.3.2 Lamella settlers

Should exclusively domestic Umlaas ef-fluent, or Umlaas effluent with minor quanti-ties of industrial Jacobs sewerage enter thesecondary treatment works, the removal of

I M I E S A MAY 1 9 9 9

COVER STORY

carbonate in order to reduce conductivity isnot required- Lime will then be dosed at alow rate into the rapid mixing tanks at theinlet of the lamella settlers and precipitateprimarily phosphate as calcium phosphate,removing heavy metals simultaneously.

An increased dose of lime is only requiredduring periods of high conductivity in theclarified water. The lime injection precipi-tates first the calcium hardness, and then themagnesium hardness. The chemical reac-tions with lime are the following:

Ca(OH), + Ca:* + 2HCO, -> 2CaC0,+ 2H,0

CaiOH), + Mg:+ + 2HC0,, -» CaCO,+ MgCO, + 2H,O

The chemical components CaCO, andMgCO, precipitate in the water in solid formof relative high density. Suspended solidsand some other particles are dragged downwith the precipitates. Silica (SiO,) isadsorbed on MgCO, and settles in the sameway.

The settling zone is equipped with modules, which are made up ofinclined (60 °) slats (1 000 mm length) made of polyvinyl chloridewith a prismatic profile. Thus two back-to-back slats form a modulecomposed of sections with a hexagonal cross-section.

The flocculated water is then distributed beneath the modulesthrough an orifice that has the distinguishing feature of extendingacross the full width of the apparatus. The water circulates upwardsbetween the slats in the opposite direction (counter-current) to thefloes, which deposit on the plates and slide downwards under theeffect of gravity.

The settled water is collected in steel pipes and combined at theoutlet:

Internal recirculation of settled sludge to the rapid mixers improvesthe chemical reaction kinetics, flocculation and the subsequent set-tling of floes. One recirculation pump per lamella settler continuouslydraws settled sludge from the bottom of the settler structure andpumps at a constant rate (5% of max. flow rate) to the rapid mixer atthe inlet of the lamella settlers.3.3 Dual-media filtration

The settled water fio ws by gravity after neutralisation with carbondioxide from the lamella settlers to the dual-media filter plant.

The addition of a coagulant and/or a polymer (polyelectrolyte, PAM)can enhance the performance (turbidity, filtration rate) of filters.

Four dual-media filter cells are fed via a distribution channel. Aninlet orifice with isolating penstock at each filter cell assures equalrepartition of the flow.

OTV- a new player in the SA market

Who is in the consortium?jparfwm Water Recycling (Ply) Ltd is a consortium of the following compani.

OTV fa subsidian' of Companie Genérale des Eau.\)Kim Ian i Corporate Services (Ply) Lidlimp.1™ W.itór ServicesZctarfiein

I» Marubeni i A Japanese Investment Consorthim)^CliH.-HnWinss (US; Inc.

Since I S>33. the OTV Group hasbeen active in the design, construc-tion, upgrading and managementof uentmem plums for drinkingwilier, wastewater and industriéeffluent,'as well as sludge incin-eration or conversion.

As the ieydingsubsidiary of ¿ ^ 'Genérale desEaux in thefield of watertreatment engi-neering, theOTV Group oper-ates world wide, ei-ther directly or throughits subsidiaries.

At the cutting edge of technol-ogy through its international re-search centre near Paris, France,the OTV Group developstrcustomised solutions and isable-^to tailor its operational methods toall types of requirements, frornsmall facilities to large-scaleprojects.Two major precepts provide thethrust for OTVs research and de-velopment policy :• satisfy both present and fu-

ture needs of all customers,• develop technologies that of-

fer technical performancewhile coping with economi-cal climates.

In addition to conventionalwastewater treatment facilities,OTV designs and develops com-pact, covered or undergroundplants. These are fully integratedinto the most sensitive locations.

i¿ Oír

They fully R-spect environmen-tal imiíer.iitiwes, MKI deliver'ztro nuisance' performance -without «lour, noise or impair-ment lu the landscape.

In design and construction,OTV has proveu its abil-

¡ty to adapt tarnetti-ods io meet actual

requirements,and to deliver

, ~ completetum-

key projects? ,OTV's expo-*

rience and know-how form the ba-

sis for active synergiesbetween construction and op-eration. In France, OTV is aleading operator of wastewatertreatment plants. -' -y-.

On the strength of its'fbrteigiWsubsidiaries and the devdop-ment of partnership iigrcenients,the OTV Group now generatesover half its touii revenues ininternational operations.

In France, the OTV Grouphas built or refurbished 130potable water treatment plantsover the past ten years. Theseplants have a total capacity offour million cubic metres perday, and supply water to 20million customers, OTV has^other potable water facilities in-ternationally which service afurther 27 million people.

During the last decade, 200wastewater treatment facilitieswere built in France and othercountries.

IMIESA MAY 1999

COVER STORY

Backwashing of the dual-filters may betriggered:

- through detection of clogging of the fil-ters (increase in headloss),

by means of a time-switch,- manually (SCADA or local control

panel).The operator will be able to choose

the manner in which the washing isstarted.

The design of the filters, and notablythe thickness of the filter layers enablesa complete washing (water and air) to becarried out in seven minutes, and rins-ing (water only) in four minutes.3.4 Ozone production and ozonecontact tank

Ozone (Os) gas is dosed for effective dis-infection, colour removal and breakdown ofcomplex organic matter. As ozone is a highlytoxic substance, no ozone will be stored onsite, and the instant demand will be generatedfrom pure oxygen using last technologyozone generators.

The ozonation system will be able to pro-duce up to 12 kg of O3 per hour, for a 5 g/m3

maximal dosage, based on a 85% gas trans-fer efficiency.

The simulations showed a satisfying effi-ciency of the ozone process, with an averageconcentration of 2 g of O3 / m

3 of water. Thisstep of the process will reduce the colour andbreak a fraction of the hard COD remaining,in smaller molecules. The transformed CODwill have the particularity to be biodegrad-able COD that can be treated on biologicalGranular Activated Carbon (GAC)contactors.3.5 GAC contactors

The water flows from the ozone contacttank to the GAC contactors in a concrete chan-nel that distributes the flow on four contactorcells. Although the contactor is basically afilter similar to the dual-media filters, its pur-pose is to provide contact between bacteriafixed on the activated granular carbon andthe water. The term contactor is therefore pref-erable.

The backwash cycle is similar to the dualmedia filters, however, the contactor runcycles are significantly higher (three to fivedays). Since bacteria is responsible for theperformance of the contactor, the GAC ma-terial does not require periodic replacementand regeneration as is the case with conven-tional activated carbon working on the ad-sorption principle. Replacement of the GACis expected after approximately ten years op-

SM On'wistmttrlntfBMtpint k Ittfwf, fma

eration due to attrition of the material.The design of the contactors, and notably

the thickness of the material enables a com-plete washing (water and air) to be carriedout in ten minutes, and rinsing (water only)in seven min utes.3.6 Chlorine contact tank / reclaimedwater pumping

The existing chlorine contact tank will beused for final disinfection of the reclaimedwater with chlorine gas using the existingequipment. The chlorine residual is kept atapproximately 0,5 mg/¿C12, The chlorine con-tact tank will be covered with a light roof inorder to ensure that no contaminants can en-ter the reclaimed water in the last stage oftreatment.

The chlorine contact tank also functions asa pump sump for the fixed speed reclaimedwater pumps.

3.7 High level storage tank / potablewater addition

The existing HLST is used for ensuringsufficient head for reclaimed water distribu-tion and to provide additional operationalsafety. The incoming water is directed to-wards the tail end of the HLST while thereclaimed water leaves at the head end. Suf-ficient water exchange is thus ensured.

Potable water back up can be added to theHLST via a ND500 pipe. If can be added inlarge quantities by opening a ND500motorised butterfly valve in order to replaceor supplement reclaimed water.

Smaller quantities of potable water can beadded at a proportional flow rate (dilutionfactor can be set at SCADA) to the instanta-neous demand by industries (sum of all cli-ent flow meters). A temporary quality prob-lem can thus be instantly corrected. ^ B

. .?ep¡toi^; . 1'F,L0W DIAGRAM FOR 47 500 m/d OF RECLAIMED WATER I '?

"T-?"1 ' - 'LT.Í *

IMIESA MAY 1999

Press Release 26 October 1999

Building foundations for development TI"Q,0 Z\

Development Bankof Southern Africa

DBSA and RMB sign R55 million with D W> • • • • •

' i •

The Development Bank of Southern Africa (DBSA) and Rand Merchant Bank, z division

of Firstrand Bank Limited (RMB) today signed loan agreements totalling R55 million with

Durban Water Recycling (Pty) Ltd (DWR). The funding is to expand the existing

secondary treatment works at the Durban Southern Wastewater Treatment Works and to

build a new tertiary treatment works with a maximum capacity of 47,5 Mega litres per

day.

*

The total investment is approximately R72 million of which DBSA is contributing R34

million and RMB approximately R21 million. The DBSA contribution includes a French

Export Credit Facility of approximately R15,4 million, emanating from a Protocol signed

between the French Government and the South African Government.

The Project is a 20-year public-private partnership concession between the Durban

Metropolitan Council (Durban Metro) and DWR for the treatment of domestic sewage

and, to a limited extent, industrial waste water at the new tertiary treatment works. The

treated water will be sold to high-volume water consuming industries in the southern

Durban industrial basin, substituting potable water currently consumed by these

industries. - ' • . ' . .

Commenting on this agreement, DBSA Manager for Private Sector Investments John

Barton-Bridges said: "the Project is the first build, own, operate and transfer (BOOT)

project of its kind in the water sector in South Africa and will be partly funded by way of

limited-recourse project financing."

DWR is a South African company formed by Omnium de Traitement et de Valorisation,

OTV, a subsidiary of Vivendi, (a French Company and one of the largest and well-known

water operators in the world) with local partners Khulani Holdings Ltd, Umgeni Water

Services (Pty) Ltd, Zethachem (Pty) Ltd and Marubeni Europe Pic.

Barton-Bridges noted that the Project has substantial developmental impacts including:

• making available additional potable water for domestic use which enables the Durban

Metro to delay capital expansion programmes for at least five years;

• a very strong environmental benefit by introducing a further treatment process before

releasing effluent into the sea; •

• it introduces the latest technology in water treatment to the South African market

through foreign investment; and

• the Project will create several high-skilled jobs and will contribute to the development

of the local community through a tertiary education programme for students with an

interest in the water and waste water sector.

For further information, please contact:

Karen Breytenbach - Project Manager,011313 3522 •

or

John Barton-BridgesManager, Private Sector InvestmentsOil 313 3004

Business Day

04 November 99

Industry to use water converted from effluentNicolaJenvey •

DURBAN — Durban Metro Water Ser-vices has sealed a R74m public-privatepartnership that will result In industrialquality water, converted from partiallytr '-;d effluent, being supplied to in-<k .y instead of drinkable water.

Far from being unhappy about re-ceiving water with a distinctly brown-ish tinge, large industries and the en-vironment will reap benefits from thedeal, which will also ease the demandfor drinking waterin Durban. . ,.

A consortium, Durban Water Recy-cling, has won the tender to treat about25% of the Durban Metro Services'vaste water.

It will receive partially treated efflu-ent from the Metro Water Services, ef-fectively alleviating the pressure on the

metro services, which are struggling tocope with the inflow of water to itstreatment plants.

The consortium includes Frenchgroup Omnium de Traitement et de Val-orisation, Marubeni Europe, KhulanIHoldings, Umgeni Water Services andZetachem.

The project, financed jointly byRand Merchant Bank and the Develop-ment Bank of SA, allows the consortiumto .convert the effluent into industrialquality water and pass ¡ton to contract-ed users. • .-.

The project received the green lightwhen pulp and paper group Mondisigned up as the biggest user of thetreated water, replacing its.demandsfor potable water in the production pro-cess. Oil refinery Sapref has followedsuit and Durban Water Recycling is ne-

gotiating with more industries.Durban Water Recycling MD Oliver

Marche said the participation by Mondiwas significant, since the water de-manded had to be consistent and with-out contamination that would disruptthe paper manufacturing process.

The close proximity to DurbanMetro Water Services and the possibili-ty of constructing the treatment plantnext lo Mondi further added to the pro-..

"ject'sviability. .: ,. ".:.- ;•!'Durban Metro Water Services execu-

tive director Neil Macleod said the pro;ject was "an idea] opportunity" to provewhat was possible given co-operationbetween the public and private sectors.

Marche said: "Particularly pleasingis the environmental saving for Durbanand its surrounding areas." The plantwill be operational in 20 months. :<%?<*•

••-"• j"*"~"iTnn*Tr*irmn"-""'-' •

18 BUSINESS DAY,Thursday.November4 1999

Durban Water Recycling

The first privately financedcommercial wastewater recycling plant

in South Africa

Rand Merchant Bank Special ProjectsKey arrangers for

Public Private Partnerships

RAND MERCHANT BANKSPECIAL PROJECTS

mDITIOHAL':VALUES. INNOVATIVE IDEAS.