concept design project 7 sewage and septage...

MAYNILAD WATER SERVICES, INC.MWSS Compound, Katipunan Road, Balara, Quezon City

DRAFT FINAL REPORT

CONCEPT DESIGNProject 7 Sewage and Septage

Treatment Plant

August 2006

Program Management GroupMaynilad Water Services Inc.2nd Floor Engineering BuildingOld Balara, Katipunan Road, Quezon CityTelephone No.: +632.433.6978Facsimile No.: +632.435.2128Website: http://www.mayniladwater.com.ph

Copyright C 2006 by Program Management Group. All rights reserved. The concepts and informationcontained herein are the property of MWSI. Use or copying of this document in whole or in part without thewritten permission of MWSI constitutes an infringement of copyright.

Project 7Prototype STP/SpTP8/17/2006

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L Document History and Statusl Checked/Reviewed Approved by / DateRevision Date Issued Prepared by by Signature Approved

A. S. AugustDraft Final August 2006 Sampiano M. R. Pedron P.N. Rosete 2006

J.C. S. Iglesia

F. A. Arellano

Distribution of CopiesRevision Copy No. Quantity Issued to

Draft Final 1 1 MWSI2 1 DENR3-: MWSS

Printed : 17 August 2006Last Save : 17 August 2006Filename : CD:/Project 7 Concept Design ReportAuthor : A.S.SampianoOffice : Water Sources and Wastewater Facilities Development (WSWFD), PMGManagers : (1) M.R. Pedron, Manager -WSWFD, PMG

(2) J.C. S. Iglesia, AVP - Program Planning and Design, PMGSupport Group : Environment Managernent Dept., Sewerage and Sanitation Dept.Version : Draft Final

Project 7Prototype STP/SpTP8/17Q2006

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Table of Contents

Executive Summary .................................. vSection 1. Introduction .........................................................................

1.1 General Background ............................ 11.1.] World Bank Mission .......................... 1

1.2 Objectve ....................... 2 ......... 21.3 Limitation of the Study ........................... 2

Section 2. Quezon City Communal System and Its Condition ........ 32.1 Project 7 Imhoff Tank ............................ 5

Section 3. Review of the Pre-feasibility Report ................. 8Section 4. MWSI Proposed Alternative 0.....................

4.1 Design Assumptions and Criteria ..................... 104.1.1 Service Areas and Land se .................... 104.1.2 Projected Sewage and Septage Volume ............. 104.1.3 Wastewater Characteristics and Polluition Loading....... 10

4.2 Process Flow for Prototype STP/SpTP .................. 114.2.1 Components of Proposed .SpTP .................. 124.2.2. ('ompotnents of Proposed .S7P ................... 134.2.3 Odor Control acili 4.........................14

4.3 Theoretcal Performance ..........................144.4 Improvement in the Level of Service ................... 16

Section 5. Estimated Capital and Operating Costs ............... 165.1 Estmated Capital Expenditures ...................... 165.2 Estimated Operabng Expenses ...................... 18

Section 6. Recommendations ........................... 19Section 7. Other Issues and Concerns ..................... 20

7.1 Social Acceptability .............................207.2 Traffic Accessibility .............................. 20

List of FiguresFigure 2.0-1 Location Map of Project 7 and Project 8 ................... 4Figure 2.0-2 Plan and Section of the Existing Imhoff Tank ................5Figure 2.1-1 Site Layout of Imhoff Tank Facility in Project 7 ...............6Figure 2.1-2 Influent/ Effluent BOD Levels against DENR AO 35 Required Standards. 7Figure 4.2-1 Process Flow Diagram for Proposed Project 7 Prototype STP/SpTP . 12Figure 4.3-1 Mass Balance Flow Diagram .........................15

List of TablesTable A Summary of Capital and Operating Cost .................. viTable 2. 1-1 Monthly Billed Volume (cmd) for Sewered Customers in Veterans Village. 7Table 2.1-2 Monthly Influent Data for Project 7 Imhoff Tank ................8Table 2.1-3 Monthly Effluent Data for Project 7 Imhoff Tank ................8Table 4.1.3-1 Monthly Influent Data for Dagat-Dagatan Septage Treatment Plant . 11Table 4.2.3-1 Classification and Source of Odor ........................ 14Table 4.3-1 Theoretical Performance of Proposed Prototype STP/SpTP ....... 16Table 5.1-1 Construction Cost Estimates of the Prototype STP/SpTP ..........17Table 5.1-2 Breakdown of Cost per Chamber ......................... 18Table 5.2-1 Estimated Operating Cost of the Prototype STP/SpTP ............19


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Abbreviations and Acronyms

ADF - Average Daily FlowAO - Administrative OrderBOD - Biochemical Oxygen DemandCMSS - Central Manila Sewerage SystemCOD - Chemical Oxygen DemandCST - Communal Septic TankEDSA - Epefanio delos Santos AvenueEO - End-of-YearGEF - Global Environmental FacilityMOA - Memorandum of AgreementMP - Master PlanMTSP - Metro Third Sewerage ProjectPLC - Programmable Logic ControlRAS - Returned Activated SludgeSBR - Sequencing Batch ReactorSpTP - Septage Treatment PlantSS - Suspended SolidsSTP - Sewage Treatment PlantTSS - Total Suspended SolidsUASB - Upflow Anaerobic Sludge BlanketWAS - Waste Activated Sludge

DENR - Department of Environmental and Natural ResourcesLLDA - Laguna Lake Development AuthorityLMTP - La Mesa Treatment PlantMWCI - Manila Water Company, IncorporatedMWSI - Maynilad Water Services, IncorporatedMWSS - Metropolitan Waterworks and Sewerage SystemNHA - National Housing AuthorityWB - World Bank

m - Meter(s)m2 square meter(s)cum. - cubic meter(s)mL - Millilitermg/L - Milligram per liter(s)cmd - Cubic meter per dayMPN - Most Probable NumberpH - potential HydrogenPhp - Philippine PesoSqm - Square meter(s)USD - United State Dollar


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Executive Summary

World Bank has a mission to reduce pollution loading discharges in Metro Manila area.Through the Global Environmental Facility - World Bank Technical Assistance (GEF-WBTA) for Manila Third Sewerage Project (MTSP) under DENR, a consultant has beenengaged to conduct a pre-feasibility study for the prototype treatment plant for sewageand septage. Several facilities within the MWSI concession area have been consideredand due to its advantages the existing Imhoff Tank facility in Project 7, Quezon City hasbeen recommended to be the pilot project. The existing facility will be rehabilitated andupgraded to accommodate a given amount of septage. The consultant's study alsoindicates that the facility owner has to invest a certain percentage of the total projectcost.

This report presents the results and recommendations of a study to develop analternative concept design for the proposed prototype sewage/septage treatment plant(STP/SpTP). This study aims to: (a) develop a process flow using state-of-the-arttechnology; (b) examine potential savings in capital expenditure and operating costs; and(c) assess other issues and concerns on environmental and social impacts of the project.

Major activities of the study involve data gathering, review and updating of water qualitydata, developing various process flow options, and estimating capital and operating costsfor the proposed altemative.

The proposed prototype STP/SpTP will be an underground facility. The treatmentfacilities have been designed to accommodate an estimated sewage flow of 2,400 cmdfrom the Veterans Village in Project 7 and an additional septage volume of about 240cmd from other areas in Quezon City (west) and Caloocan.

Proposed Altematives of the Prototype STP/SpTP in Project 7, Quezon City

In order to meet its sanitation target at a minimum investment cost, MWSI developed analternative scheme other than that indicated in the pre-feasibility study, summarized asfollows:

1. Pre-feasibility altematives* Sewage (2,400 cmd) + Septage 0% (O cmd) - full aerobic biotreatment;* Sewage (2,400 cmd) + Septage 10% (240 cmd) - full aerobic biotreatment;

Sewage (2,400 cmd) + Septage 5% (120 cmd) - anaerobic-aerobic biotreatment;* Sewage (2,400 cmd) + Septage 10% (240 cmd) - anaerobic-aerobic biotreatment* Sewage (2,400 cmd) + Septage 15% (360 cmd) - anaerobic-aerobic biotreatment

2. MWSI proposed altemative* Sewage (2,400 cmd) + Septage 10% (240 cmd) - full-aerobic biotreatment;

The pre-feasibility alternatives consist of full aerobic biotreatment (SBR) and anaerobic-aerobic biotreatment (UASB+SBR). The existing Imhoff Tank with 2 chambers will beupgraded to 2 balancing tanks to hold the mixture of sewage and filtrate in one tank andscreened and degrited septage in the other.


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For scenarios Al (pure 2,400 cmd sewage) and A2 (Al+ 240 cmd septage), full aerobicbiotreatment using 2 fill-and-draw Sequencing Batch Reactors (SBRs) is applied prior todischarge of effluent to Culiat Creek.

The treatment process for scenarios B1 (Al+120 cmd septage), B2 (A1+240 cmdseptage) and B3 (A1+360 cmd septage) involves anaerobic-aerobic biotreatment utilizinga UASB or an Upflow Anaerobic Sludge Blanket and an SBR. This process is similar tofull aerobic biotreatment except that, the mixture of filtrate and sewage is pumped to theUASB for carbon scrubbing then to the SBR for effluent polishing.

The alternative process proposed by MWSI treats sewage and septage separately. Two(2) SBR's will be used to treat sewage and septage in series. Septage is treated usingan equalization tank for pre-aeration before it goes to the SBR (SpTP). The primaryeffluent is mixed with fresh sewage to increase the amount of micro-organisms beforesubjecting to a biotreatment in another SBR (STP) for discharge to Culiat Creek

Estimated Capital and Operating Cost

Capital costs consist of civil works, supply and installation of equipment, electrical works,instrumentation and cabling. Operating costs identified are power cost, personnel,chemicals, sludge disposal, maintenance and laboratory works. However, mark-up,engineering and construction management, value added tax (VAT), overhead, and othercontingencies have also been included in the study. Table A shows that alternative B3has the highest estimated capital and operating costs at 272M Php and 44M Php,respectively, while alternative C has the least with about 81M Php and 21M Php,respectively. Thus, a potential savings of about 191M Php in capital expenditures and23M Php in annual operating costs may be realized with alternative C.

Table A Summary of Capital and Operating Costs

. Capital Cost Operating CostAlternatives (MPhp) (MPhp)

I. Pre-feasibility Altematives (Mixed Treatment)A. Full Aerobic Process

A.1: 2400 cmd (Sewage) 114.87 12.69A.2: A.1 + 240 cmd (1 O%Septage) 189.64 38.30

B. Anaerobic-Aerobic ProcessB.1: A.1 +120cmd(5%Septage) 183.76 23.06B.2: A.1 + 240 cmd (1O%Septage) 229.84 33.42B.3: A.1 + 360 cmd (15%Septage) 272.42 43.92

II. Separate STP/SpTPC. Full Aerobic Process

C: 2400 cmd (Sewage) + 240 cmd (Septage) 80.97 20.74

Project 7Prototype STP/SpTP8/17/2006Page vi

Recommendations

MWSS/MWSI recommends that alternative C, full-aerobic biotreatment process, beadopted for the proposed prototype STP/SpTP in Project 7, Quezon City at an estimatedcost of 81MPhP, using the 1.3M USD WB grant plus capital expenditures of about 10MPhp. An annual operating budget of about 21 M Php has to be allocated, as well.

MWSS/MWSI shall prepare the bidding documents for design and build (B&D) contractfor the underground prototype STP/SpTP.

Social acceptability and accessibility are issues that need to be addressed.

Project 7Prototype STP/SpTP8/17/2006Page vii

1. Introduction

1.1 General Background

Metro Manila which lies at the northwestem part of the Philippines is bounded by ManilaBay in the west and Laguna de Bay in the south. It covers thirteen cities (Caloocan, LasPinas, Makati, Malabon, Mandaluyong, Manila, Marikina, Muntinlupa, Quezon City,Paranaque, Pasay, Pasig and Valenzuela) and four municipalities (Navotas, Pateros,San Juan and Taguig).

Metro Manila is a political, educational and economic center of the Philippines. The riseof urbanization in this area resulted to rapid increase of pollution loading in bodies ofwater, particularly Pasig River, composed of about 75% domestic wastewater and 25%industrial and commercial discharges1.

MWSS was created as a government owned and controlled corporation in 1971,responsible for water supply and sanitation in Metro Manila and portions of Cavite andRizal provinces. In 1997, its operations were privatized through concession agreementswith Manila Water Company, Inc. (MWCI) for the East Zone and Maynilad WaterServices, Inc. (MWSI) for the West Zone. Each concessionaire agreed to provide watersupply, sewerage and sanitation services to the residents within its coverage area untilthe end of concession period in year 2022.

1.1.1 World Bank Mission

Several funding institutions, one of which is World Bank (WB), have assisted MWSS inits sewerage and sanitation programs by providing financial assistance for varioustechnical studies and projects focused on the improvement of existing sewerage andsanitation facilities.

WB has a mission to reduce pollution loading discharges in Metro Manila area thru theGlobal Environmental Facility (GEF) components of the Metro Third Sewerage Project(MTSP). The development objective of the GEF-MTSP is to create an enablingenvironment to scale up investments in priority areas in sewerage and sanitation in theLaguna de Bay - Pasig River - Manila Bay watershed areas through2:

a. Strengthening of partnerships among stakeholders;b. Upgrading of sector plans and policies based on environmental and

economic principles;c. Piloting of innovative financial mechanisms to facilitate private sector

investment; andd. Demonstration of the viability of combined sewage and septage treatment

in Metro Manila.

I Manila Water Company, Sewerage and Sanitation - Metro Manila2 Aide-Memoire, GEF-MTSP Preparabon Mission, January 30 to February 7, 2006

Project 7 Prototype STP/SpTP8/17/2006

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In the pre-feasibility study conducted by a consultant for DENR, these objectives havebeen transalated into 6 components and under Component 5, the existing wastewaterfacility (imhoff tank) at Project 7 will be rehabilitated and upgraded to accommodate bothsewage and septage. The Project 7 Sewage/Septage Treatment Plant (STP/SpTP) willserve as a pilot project which aims to demonstrate the technical, financial, social andeconomic viability of such project for similar plants within MWSS responsibility in thefuture.

WB has allocated 5M USD grant for this mission, and of which 1.30M USD has beenearmarked for the said pilot project. The grant agreement is between WB and theDepartment of Environment and Natural Resources (DENR), as the executing agency.DENR will, likewise, enter into a Memorandum of Agreement (MOA) with MWSS for theimplementation of the pilot project.

1.2 Objective

This technical study aims to present another feasible alternative for the combinedsewage/septage treatment plant, to minimize investment cost and be able to optimizethe WB grant allocation. Its specific objectives are as follows:

a. Develop a process flow using state-of-the-art technology;b. Estimate the potential savings in capital expenditure and operating costs;

andc. Assess issues and concems on the environmental and social impacts of

the project.

1.3 Limitation of the Study

This design concept is limited to the study of the sanitation requirements of MWSI.Water consumption data of sewered customers in Veterans Village have been used toestablish the capacity of the combined sewage and septage treatment facilities. Theestimated capital expenditures and operating costs are budgetary based on parametricunit costs. A detailed financial/economic analysis to determine FIRR/EIRR is excluded.


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2. Quezon City Communal System and Its Condition

MWSI is currently operating four (4) sewerage systems namely: Central ManilaSewerage System (CMSS), Dagat-dagatan System, Makati Isolated System andQuezon City Communal System, serving around 11% (Sewerage program, EO 2005) ofthe total population under the West Concession Area. In addition, MWSI provides freedesludging services to residential and semi-business customers, currently estimated at19% (Sanitation program, EO 2005) of the total population within the service area.

The Quezon City Communal System serves Project 7 and Project 8 in Quezon City andhas around 4,000 sewer service connections for residents, mostly, belonging to mediumand high-income groups. Project 7 and Project 8 are bounded by major roads, such as,Epefanio delos Santos Avenue (EDSA), Congressional Avenue, Roosevelt Avenue,West Avenue and Mindanao Avenue. The topography in this area is almost flat with anaverage elevation of 25m.

Wastewater generated in the area is collected through the sewer system and treated inthe imhoff tank going to a communal septic tank in Project 7 and through the communalseptic tanks (CST) in Project 8 before discharging to Culiat/Duria Creek. Figure 2.0-1shows the location of the existing CSTs and Imhoff Tank in Project 7 and Project 8.

The existing imhoff tank is located at 11 Road A. St., Anthony Village, Project 7, QuezonCity. It was constructed by the National Housing Authority (NHA) in 1955 and handedover to MWSS for operations and maintenance. The imhoff tank is composed of two (2)open chambers with a dimension of 4.70m (width) x 9.40m (Length) x 7.65m (depth)each and has a design capacity of 1,200 cmd. It drains an area of about 45.6 hectares,which translate to 1,753 service connections (inclusive of service area covered bydownstream communal septic tank) at Veterans Village. The facility is operational,however, effluent is not complying with the standard specified in DENR AO 35 for inlandwater class C. The tank also causes odor problem in the area due to various escapinggases. Figure 2.0-2 shows the plan and section of the existing Imhoff Tank.

Effluent from the Imhoff Tank is discharged downstream to a communal septic tank(CST #22) located at Roosevelt Avenue, which was also constructed in 1955 andhanded over by NHA to MWSS. It has a dimension of 4.Om (width) x 10.0rn (length) x3.0m (depth) and a design capacity of 95cmd. The CST has been suspected to beoccupied by informal settlers and/or commercial and institutional establishments.

Similar to the case of CST #22 in Project 7, the CSTs in Project 8 were constructed in1954 by NHA and handed over to MWSS. There are three (3) existing CSTs located inthat area with dimensions of 4.Om (width) x 13.7m (length) x 5.5m (depth) each and hasan average design capacity of 540cmd. CST #23 serves 26 hectares; CST #35, 37hectares and CST #35a, 36 hectares. The existing CST's are operational but occupiedby informal settlers and/or commercial and other establishments.


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Figure 2.0-1 Location Map of Project 7 and Project 8Project 7 Prototype STP/SpTP

8,t17/2006Page 4 of 20

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Figure 2.0-2 Plan and Section of the Existing Imhoff Tank

2.1 Project 7 Imhoff Tank

The Imhoff Tank facility in Project 7 stands in al,300 m2 lot where portions of the area iscurrently occupied by a repair shop, a stock shop, an office building and a warehouse.The imhoff tanks are desludged every six months with sludge taken to Dagat-dagatanSTP-SpTP for further treatment. Figure 2.1-1 shows the site layout of the facility inProject 7.

The estimated average daily water consumption (billed volume) in the area is about2,400 cmd, taken from the sewered customers in Veterans Village from 1999 to 2002.Table 2.1-1 shows the monthly billed volume of sewered customers in Veterans Village.


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However, record shows that only 1,200 cmd average daily flow (ADF) enters the existingimhoff tank. Discrepancy is mainly due to gradual development in the area from year1955 to present in which almost fffty percent (50%) of the total households in VeteransVillage with individual septic tanks discharge their wastewater to the drainage system.

Figure 2.1-1 Site Layout of Imhoff Tank Facility in Project 7

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MWSI regularly monitors the influent and effluent quality of Project 7 Imhoff Tank 24hours a day. Samples are taken to the Central Laboratory, located at La MesaTreatment Plant (LMTP-1), for analysis and results are submitted to Laguna LakeDevelopment Authority (LLDA) in compliance with DENR AO 35.


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Table 2.1-1 Monthly Billed Volume (cmd) for Sewered Customers in Veterans Village

Month 1999 2000 2001 2002 Average

January 2,568 2,311 2,175 2,311February 2,568 2,837 2,465 2,668March 2,568 2,390 2,155 2,390April 2,568 2,370 2,230 2,370May 2,568 2,472 2,097 2,472June 1,835 2.603 2,249 2,249July 2,568 1,362 2,165 2,165 2,166August 2,568 2,279 2,178 2,178 2,229

Septem ber 2,568 2,663 2,264 2,264 2,416October 2,568 2,498 2,446 2,206 2,472November 2,568 2,615 2,553 2,216 2,661December 2,568 2,465 2,760 2,016 2,516

Average 2,868 2,668 2,418 2,192 2,403(cm d ) _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Recent data have been evaluated to determine the characteristics of the wastewater inthe area. Average Biochemical Oxygen Demand (BOD), the most widely usedparameter for organic pollution that depletes dissolved oxygen in water, is about 106mg/L, while Chemical Oxygen Demand (COD), those refractory organics that can resistbiological treatment, is about 246 mg/L. Ratio of COD to BOD of around 2.32 is withinnormal characteristic of most sewage in other treatment facilities. Figure 2.1-2 showsthe current influent and effluent BOD levels against the required standard of DENR AO35.

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200 -5.T* n-o M AO 35 kM d Om Chu

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Apr- May- Jun- Jul- Aug- Sep- Oct- Nov- Dec- Jan- Feb- Mar- Apr-05 05 05 05 05 05 05 05 05 06 06 06 06

Figure 2.1-2 Influent/Effluent BOD Levels against DENR AO 35 Standards


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Total Suspended Solid (TSS), aesthetically not acceptable that may deplete oxygenlevels in water, is around 88 mg/L. Records show that low concentrations of majoreffluent contaminants are discharged to Culiat creak. Table 2.1-2 presents the influentdata for Project 7 Imhoff Tank and Table 2.1-3 presents the effluent data.

Table 2.1-2 Monthly Influent Data for Project 7 Imhoff Tank

Parameter Unit Apr-05 May-05 Jun-05 Oct-05 Nov-05 Dec-05 Jan-06 Feb-06 Apr-06 Average

BODs mg/L 140 150 107 93 125 78 140 70 48 10COD mg/L 256 465 168 144 215 159 458 151 202 246TSS mg/L 38 57 58 80 97 88 58 240 78 88Color 29 14 16 8 19 8 10 15 20 15Temperature OC 28.9 - - 27.0 27.7 26.4 26.1 26.9 27.1 27.2pH 7.0 7.3 7.2 7.2 7.3 7.1 7.5 7.3 7.3 7.2Oil& Grese mg/I 16 26 - 15 12 12 5.2 17 11 14Coliform MPN/100mL 7.OE+07 8.OE+07 8.OE+07 5.OE+07 3.0E+08 5.0E+07 8.0E+07 3.0E+07 2.2E+08 1.1 E+08

Table 2.1-3 Monthly Effluent Data for Project 7 Imhoff Tank

Parameter Unit Apr-OS May-05 Jun-05 Oct-OS Nov-05 -Dec05 Jan-06 Feb-06 Apr-06 Average

BOD5 mg/L 130 100 80 87 73 83 57 41 81COD mg/L 382 210 140 109 150 145 467 194 167 218TSS mg/L 146 30 68 60 52 78 47 196 71 83Color 29 [ 15 15 12 10 10 10 15 15 15Tefferature OC 29.9 - - 27.5 27.9 26.7 27.1 27.8 28.1 27.9pH 7.0 7.2 6.9 7.2 7.2 6.7 7.6 7.1 7.3 7.1Oil & Grease mg/L 26 25 - 11 8.4 11 5 18 16 15Coliform MPN/100mL 5.0E+047E+0710 8.0E+07 1.3E+08 2.3E+07 3.OE+07 7.OE+07 5.OE+07 1.8E+07 5.5E+07

Since the treatment facility has been constructed 50 years ago, odor problem has beenencountered that presents inconvenience to the residents. Its efficiency of removingorganic pollutants decreased from 30-50% to almost 23%. Treatment efficiency for othercontaminants, likewise, decreased considerably.

3. Review of the Pre-feasibility Report

A sewerage and sanitation Master Plan (MP) for MWSS service area was updated last2005 indicating preference for aerobic-anaerobic treatment process. Consequently, WBexpressed that it would be beneficial to have a prototype STP-SpTP that will serve as apilot project for other similar treatment facilities in the future. Two sites under MWCI andfive sites within MWSI area have been considered. The facility located at 11 Road A,St. Anthony Village Project 7, Quezon City, which drains about 45.60 hectares of

Project 7 Prototype STP/SpTP81170

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sewerage area, has been selected due to a number of advantages: (a) site is withinMWSI concession area; (b) Imhoff Tank has a poorly operating treatment system thatpollutes Culiat creek; (c) site has available area of about 1,300 sqm; (d) no informalsettlers on site; (e) land is government-owned; (f site covers a significant number ofseptic tanks in adjacent areas; (g) site is close to MWSI monitoring station; and (h)amount of sewage flow is about 2,400 cmd only.

Five (5) scenarios have been evaluated with each scenario uses an estimated sewageaverage daily flows (ADF) of 2,400 cmd. Alternatives are summarized as follows:

* Sewage (2,400 cmd) + Septage 0% (0 cmd) - full aerobic biotreatment;* Sewage (2,400 cmd) + Septage 10% (240 cmd) - full aerobic biotreatment;* Sewage (2,400 cmd) + Septage 5% (120 cmd) - anaerobic-aerobic biotreatment;* Sewage (2,400 cmd) + Septage 10% (240 cmd) - anaerobic-aerobic biotreatment* Sewage (2,400 cmd) + Septage 15% (360 cmd) - anaerobic-aerobic biotreatment

The pre-feasibility preferred altematives (Scenarios #2 and #5) involve full aerobicbiotreatment (SBR) and anaerobic-aerobic biotreatment (UASB+SBR). Other processcomponents include imhoff tanks conversion to balancing tanks, new sewage inletworks, septage acceptance area, biosolids dewatering system, new chlorination systemand contact tank, effluent reuse and odour control. The existing Imhoff Tank with twochambers will be upgraded to two balancing tanks to hold the mixture of sewage andfiltrate in one tank, and screened and degrited septage in the other. The existing officespace will be converted to a control room and a laboratory. It has been proposed todemolish several old structures to accommodate the new treatment plant.

In full aerobic biotreatment (SBR) for scenarios #1 and #2, screened/degrited septageand waste activated sludge (WAS) from a balancing tank are pumped for dewatering tothe biosolid building where filtrate is transferred to another filtrate/sewage balance tank.The mixture of filtrate and sewage is pumped to one of the two sequencing batch reactor(SBR) tanks for biological treatment. The SBR is a fill-and-draw system and requirestwo or more reactors to operate continuously. WAS from the SBR is retumed to thesecond balancing tank while the decanted liquid is disinfected before discharging toCuliat Creek.

The treatment system in anaerobic-aerobic biotreatment (UASB+SBR) is basicallysimilar to full aerobic biotreatment, except that the mixture of filtrate and sewage ispumped to an upflow anaerobic sludge blanket (UASB) reactor for carbon scrubbing,then to the SBR for effluent polishing.

The pre-feasibility report identified all altematives that would fit in the Project 7 site.However, the estimated capital expenditures exceed the limit of GEF-MTSP for the saidcomponent, thus, cost sharing is proposed in which MWSI is required to shoulder anyamount in excess of the grant amount.


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4. MWSI Proposed Alternative

In order to meet its sanitation target and avail the WB grant at the least cost, MWSIconsidered an altemative concept design for the combined sewage and septagetreatment using a different approach. MWSI opted for a separate treatment of septageand sewage which are located in the same area. The study focused on activated sludgeprocess for sewage and septage in series.

4.1 Design Assumptions and Criteria

MWSI considered various design assumptions and criteria for the upgrading andrehabilitation of Project 7 Imhoff Tank. Major parameters considered in the study are:determination of service area and land use, equivalent discharges, wastewatercharacteristics and pollution loading. Proposed desludging sites are also included in thestudy.

4.1.1 Service Areas and Land Use

The service area for the sewage treatment plant is the Veterans Village, in which most ofthe residents belong to medium and high income groups. Septage will be desludgedfrom various locations in Quezon City (west) and Caloocan. Specifically, areas serve inCaloocan are: Baesa (AltaVista, Reparo, Rubyville), Bagong Barrio, BF Homes, BrixtonVille, Camarin Areas A and B, Capitol Parkland, Cristina Homes, Ciudad Grande, DelRey Subd, Fortune Village, North Matrix Subd, Bagbaguin (Villa Ocampo), Zabarte andBagong Silang. In Quezon City, these are: ACF Road, Baesa, Brgy Holy Spirit, BatasanHills, BIR Village, Bitoon Circle, Brgy Commonwealth, Damong Maliiit, Don Fabian,Fairview, Greenfields, GSIS Village, Gulod, Pamahay Homes, Rolling Meadow, SanBartolome, Brgy Sta Lucia, Veterans Village and Villa Verde Subd.

4.1.2 Projected Sewage and Septage Volume

The treatment facilities were designed to accommodate 2,400 cmd of sewage or 100%of the water consumed by sewered costumers in Veterans Village and a daily septagecollection of 240 cmd (10% of sewage) from adjacent areas. It is advisable to review thesewer network system to verify the actual amount of sewage entering the treatmentfacility.

4.1.3 Wastewater Characteristics and Pollution Loading

Based on samples taken and analyzed, sewage characteristics as discussed in section2.1 show low concentrations of major contaminants compared to other domesticwastewater.

Nitrogen and phosphorous contents, as a general rule used for controlling phytoplanktongrowth rates that may result to eutrophication in surface water and nitrate contamination


Page 10 of 20

of groundwater, are about 0.10-0.70 mg/L and 1.80-2.64 mg/L, respectively. Additionaltreatment for nitrogen and phosphorus removal is, thus, unnecessary in this kind ofsewage.

Influent data entering Dagat-Dagatan Septage Treatment Plant has been consideredand used as reference for septage characteristics. COD to BOD ratio of almost 7.36would require much stronger oxidant to chemically oxidize organic matter. TotalSuspended Solids (TSS), classified according to their particle sizes as non-filterablesolid, is about 14,481-51,200 mg/L. Table 4.1.3-1 indicates the concentrations ofcontaminants entering Dagat-Dagatan Septage Treatment Plant.

Table 4.1.3-1 Monthly Influent Data for Dagat-Dagatan Septage Treatment Plant

Paarmeter Lk*it Ar6 15 J"I-M 6- A& SeP05 Oct0 N.5 Dsc-M J.06 Feb.06 Aerage

131s - nyL 2,478 3,589 z349 1,655 1,853 4,063 3,438 2,471 2,235 3,520 2,68 2,752COD r- L 23,783 13,953 17,874 15,766 14,120 14,852 23,989 11,364 14,811 29,756 42,629 20,263TSS ng'L 26,733 39,788 47,15D 35,988 39,500 17,325 51,2C0 3o6o0 43,m 45,467 14,481 35,650Cobr 1,906 1,983 775 1,5S0 1,175 1,875 1,72B 1,400 1,850 2,375 1,t05 1,606TenpAe OC 322 33.5 317 30.6 29.9 29.1 30.0 31.0 29.3 29.9 30.1 30.64pH 72 64 70 7.3 7.3 7.3 7.4 7.2 7.4 7.5 7.4 7.20Cil&Grese nVL 494 1,017 - 1,872 1,831 2,513 2,65B 1,134 1,579 1,741 3,837 1,863Colfm M1PNIO'TtI 1 .3E+07 1.5E407 32E+07 23E+07 1.E+07 1.6E+07 2.9E407 1 .7E+07 2.7E+07 32E407 22E+07 2.2E+07

Nitrogen and phosphorous contents of septage are about 2.0-10.0 mg/L and 5.67-23.66mg/L, respectively. Nitrogen over phosphorus ratio shows that no additional nitrogenand phosphorus removal is required.

Coliform concentration is about 2.2E+07MPN/100mL in septage and1.1E+08MPN/100mL in sewage. Coliforms as indicator organisms of the potentialpresence of pathogens are treated through disinfection.

4.2 Process Flow for Prototype STP/SpTP

MWSI proposed alternative treats sewage and septage separately and is basically acombination of two (2) activated sludge processes. The proposed SpTP consists of barscreen, grit chamber, equalization tank, SBR, aerobic digester and centrifuge. While theproposed STP is composed of bar screen, equalization tank, SBR and chlorine contacttank. An odor control facility is, likewise, incorporated to remove undesirable odor. Theprimary effluent from SpTP goes directly to equalization tank of STP for furthertreatment. Figure 4.2-1 shows the process flow diagram for the proposed prototypeSTP/SpTP.

Project 7 Prototpe STP/SpTP8/17a2006

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SEWAGE

C k ~- fr at \

i~~ ' -, -C%l -,--'

coi*ci ccrti E

SEPTAGE - -'. o %'t

'AEROHIC j :''EoIgxo j

FILT RATE

Figure 4.2-1 Process Flow Diagram for Proposed Project 7 Prototype STP/SpTP

Screened and degrited septage, waste sludge from the SBR (STP) and filtrate from theI aerobic digester and centrifuge are stored and pre-aerated for 1 day in an equalizationtank. The mixture is then pumped to the other SBR (SpTP) for biological treatment.Waste sludge is then pumped to an aerobic digester to biologically destroy volatile solidsbefore feeding to a centrifuge. The primary effluent from the SBR (SpTP) is mixed toscreened fresh sewage in another equalization tank for dilution before it is pumped tothe SBR (STP) for biological treatment. Waste sludge produced is pumped back to anequalization tank and mixed with degrited septage. Decanted liquid is finally disinfectedusing chlorine prior to discharge.

4.2.1 Components of Proposed Septage Treatment Plant (SpTP)

a. Bar Screen/ Basket Screen - It is provided to remove coarse particles

It

that might damage downstream operation or clog weirs, pipes and valves.In addition, it could facilitate downstream operations and improve on theaesthetics of the treatment plant.

b. Grit Chamber - It is necessary to discretely settle heavy sand particlesand prevent organic suspended solids from settling. Removal of

Projedt7 ProCotpe StP/SpTP8/17/2006

hage 12 of 20

inorganic maKlers, such as grits and sand, would offer advantages todownstream operations.

c. Equalization Tank- It should be provided for storage and stabilization ofseptage by pre-aeration, especially that loading varies depending on thetraffic condition within the collection area. It is proposed that septage beretained in the tank for about one (1) day for more effective treatment.

d. Sequencing Batch Reactor (SBR) - The SBR is a fill and draw state-of-the-art activated sludge treatment system. It operates by batch andallows large number of microorganisms to biodegrade organic mattersand convert them to useful and stable gases such as carbon dioxide,nitrogen and water under an aerobic, anoxic and anaerobic conditions. Itinvolves combined carbon oxidation and nitrification/denitrificationprocesses in one reactor ensuring total treatment of biological wastes.The various operating modes using programmable logic control (PLC)are: fill, react, settle, decant and idle. Organic pollutants are, therefore,allowed to undergo a complete cycle, from aerobic oxidation to anaerobicdegradation. SBR has a removal rate of approximately 85-98% in BODand TSS, 80-95% in COD, 20-50% in Total P and 20-70% in Total N.

e. Aerobic Sludge Digester - Waste sludge is pumped from the SBR to theaerobic sludge digester to biologically destroy volatile solids. Thedigester is designed to have a minimum of 15 days solid retention timewith course bubble diffusers to aerate the tank. After digestion, volume ofvolatile suspended solids (digested sludge) is reduced/ oxidized to stableforms by about 40-50%. Stabilized sludge may be returned toequalization tank of septage treatment during low flow concentration toreduce sludge disposal problems.

f. Centrifuge - Sludge from the holding tank and aerobic digester isprocessed in the centrifuge which separates the solid from the liquidportion of the sludge. The supernatant returns to the equalization tank forfurther treatment while the solid waste may be reused as soil conditioner.

4.2.2 Components of Proposed Sewage Treatment Plant (STP)

a. Bar/Basket Screen - Functions are similar to that in section 4.3.2a.

b. Equalization Tank - Sewage and treated septage flows by gravity to theequalization tank which is similar to that in section 4.3.2c, except that pre-aeration is not applied to maintain a high level of micro-organisms in thesystem.

c. Sequencing Batch Reactor (SBR) - Functions are similar to that insection 4.3.2d.

d. Chlorine Contact Tank - Decanted sewage from SBR is further treatedwith hypochlorite solution to eliminate pathogenic bacteria and coliform


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before finally discharging to Culiat creelc The sodium hypochloritesolution is prepared in the chlorine tank and pumped by a chemicalmetering pump.

4.2.3 Odour Control Facility

Odor problems encountered in various locations within the treatment plant arebroadly classified into the following categories:

* High intensity odor areas/facilities* Medium intensity odor areas/facilities* Low intensity odor areas/facilities

The main sources of potential odor are summarized in Table 4.2.3-1.

Table 4.2.3-1 Classification and Source of Odor

Classification Sources, Area, Facility and Equipment

High Intensity Screening equipmentOdour Septage Equalization Tank

* Grit ChamberMeduim Intensity Aric Digeserodour Aerobic DigesterLow Intensity Screening FacilityOdour SBR Tank

I Centrifuge Room

4.3 Theoretical Performance

Theoretically, effluent from the proposed STP/SpTP not only meets the requiredstandard specified in DENR AO 35, but should surpass the prescribed effluent waterquality at all times. BOD5, COD and TSS concentrations are expected to decrease to 22mg/I, 72 mg/I and 30 mg/I, respectively, after treatment. Applying mass balance analysisfor all systems shows that processing 2,400cmd of sewage + 24Ocmd of septage willresult to about 2,393cmd of treated wastewater, 103cmd biosolids, and 144cmdscreened and degrited wastes. Biomass produced daily for possible reuse as soilconditioner contains about 99kg of BODs and 660kg TSS. Figure 4.3-1 presents themass balance flow diagram for the proposed prototype STP/SpTP.


Page 14 of 20

It

Od 2/ 0261

- Od&,l S075i CR

EOf .\ G2

-OdCrb oLrd Cor ,.ord

: W

I FILTRATE

I Figure 4.3-1 Mass Balance Flow Diagram

H In SpTP, the estimated overall removal efficiency in terms of BOD, COD and TSS are93%, 94% and 97%, respectively. However, treatment efficiency in STP is lower withapproximately 80% for BOD, 80% for COD, and 85% for TSS. Dilution of primaryeffluent with screened sewage and absence of pre-aeration in the system results tofurther decrease in concentration of pollution loads causing lesser amount of micro-organism in the reactor. Table 4.3-1 summarizes the theoretical performance of the

STPlSpTP.

Project 7 Prototype STP/SpTP8i17/2006

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Table 4.3-1 Theoretical Performance of Proposed Prototype STP/SpTP

Septage Treatment Plant Sewage Treatment Plant

Parameter Lndit R Eiualzation After SBR Mxhed After SBR DAO 35

Septage (Pre-aeraton) Treatrrent Sewage Eualzafon Treatment

BOD5 mg/l 2,752 963 193 109 109 22 50COD mg/ 20,263 6,383 1,277 361 361 72 100TSS rg 35,650 6,417 963 201 201 30 70

4.3 Improvement in the Level of Service

The proposed project will significantly improve Maynilad's level of service in terms of theincrease in population served from 19% (EO 2005) to 46% (EO 2008). Furthermore, itwill improve the effluent quality complying with DENR AO 35 for inland water class Cand clean water act, thus, achieving World Bank's objective to reduce pollution loadingto receiving waters. MWSI will eventually be able to avoid penalty payments amountingto 2M Php annually starting year 2010 for non-compliance.

5. Estimated Capital and Operating Cost

In this study, final recommendation will be based on the least capital expenditures andoperating cost. The cost shown are budgetary and based on parametric unit costsderived during the course of the study

5.1 Estimated Capital Expenditures

The capital costs have been determined using parametric unit costs represenfinginstalled costs of all components of the prototype STP/SpTP. The parametric unit costshave been derived from recent projects of various designers/builders of STP/SpTP's withsimilar work description and specifications.

Project 7 Prototype STP/SpTP

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Table 5.1-1 Construction Cost Estimates of the Prototype STP/SpTP

Alternative Al A2 BI B2 B3 CItem Description Treatment Procesi SB3R SBR SBR+UASB SBR+UJASB SBR+LIASB S!BR

Sewage 2400 2400 2400 2400 2400 2400-Septage o 240 ' 120 240 ' 360 240

1.0 Land sub-total (item 1) 0 0 0 0 0 02.0 CivillBuilding & Construction Mtnt sub-total (item 2) 24,412,805 33,248,290 47,626,886 60,191,847 65,618,660 32,400,0003.0 Mechanical sub-total (item 3) 43,007,200 81,841,670 64,749,235 81,626,470 103,354,706 19,080,0004.0 BectricaVklstrunentation/Cabling sub-total (item 4) 7,991,401 13,723,795 12,243,735 15,713,798 18,972,404 6,480,0005.0 Others sub-total (item 5) 7,000,000 7,000,000 7,000,000 7,000,000 7,000,000 6,000,000

T=b (FlM 82.411.406 135,813,755 131.619.888 164,2115 19445.77t 63,89K0.-- Mrk-up 8,241,141 13,581,376 13,161,986 16,453,212 19,494,577 2,898,000

Eng'g and construction Mgnt 6,592,912 10,865,100 10,529,588 13,162,569 15,595,662 6,000,000VAT 9,889,369 16,297,651 15,794,383 19,743,854 23,393,492 6,955,200

Contingencies 8,241,141 13,581,376 13,161,986 16,453,212 19,494,577 1,159,200Grand TolWl ( ) 114,871 ,98 1S9,630 U 13M379 22R840 272.420.077 8097Z02

_ _ _ _ _ _ _ _ _ _ _ _ __l 11U 7 13 W . 33 m 4M 272Q'ii ToW(MULq J_ 205 3.3 _ 28_ 4.10 4. 1.45

Table 5.1-1 which presents the construction cost estimates for all altematives showsthat altemative B3 has the highest project cost estimated at 272M Php while alternativeC has the least estimated at 81M Php. The construction costs of pre-feasibilityaltematives ranges from 42 to 236% higher than the cost of MWSI proposed alternative.Therefore, a potential savings of about 34 - 191M Php can be realized with theimplementation of altemative C. Table 5.1-2 summarizes the breakdown of the totalcost for alternative C.

Project 7 Prototype STP/SpTP81171200

Page 17 of 20

Table 5.1-2 Breakdown of Cost per Chamber

DescrptionArnountPhp USD

General Requirents 4,600,000 83,636

Odour Control System - 1,400,000 25,455Sub-total (1) 6,000,000 109,061

Sewage Treatmet Plant

Bar Screen 4,452,515 80,955Equalization Tank 6,184,049 112,437SBR 9,894,479 179,900Chorine Contack Tank 4,947,239 89,950

Sub-total (2) 25,478,282 483,241Septage Treatment Plant

Bar Screen 4,037,646 73,412Grit Chamber 3,627,294 65,951Equalization Tank 4,534,118 82,439SBR 5,440,942 98,926Aerobic Digester 7,915,583 143,920Centrifuge 6,926,135 125,930

Sub-total (3) 32,481,718 590,577

Toed N.000 ,162,Is,

Engg & Construction Mgnt 6,000,000 109,091Contractor Mark Up 2,898,000 52,691

VAT 6,955,200 126,458Contingencies 1,159,200 21,076Sfud Tld, 0 27200 1A,472,21

5.2 Estimated Operating Expenses

Operating costs refer to power consumption, chemical consumption, personnel, sludgetrucking/disposal, and administrative and overhead costs in operating the prototypeSTP/SpTP. Actual operating expenses for Dagat-Dagatan SpTP and other STPs wereused as basis for altemative C.

Table 5.2-1 presents the estimated operating costs for all alternatives. The table showsthat altemative B3 has the highest annual operating cost estimated at 44M Php whilealtemative C has the least, estimated at 21M Php. A potential annual savings of about23M Php may be achieved by implementing altemative C.

Project 7 Prototype STP/SpTP8/1712006

PageIS8of 20

Akernative Al A2 BI B2 B3 CTreatmert Prcess s8R SBR SBR+USB SBRWLASB SBR+.ASB SBRSewage 2400 2400 2400 2400 2400 2400Septage 0 240 120 240 360 240

1.0 Variable Operating Cost sub-total (item 1) 7,029,890 24,499,194 13,461,991 20,662,965 27,315,0tt 16,557,001Pow er 3,081,256 7,880,888 3,617,459 4,648,111 5,278,309 5,371,200

Labour 3,476,200 3,476,200 3,476,200 3,476,200 3,476,200 6,156,000Chencal 366,159 8,153,506 3,984,178 7,782,978 11,484,519 4,806,00Sludge Trucking 106,275 4,988,600 2,374,154 4,755,676 7,076,060 223,800

2.0 Rxed Operating Cost sub-total (item 2) 2,371,850 3,867,681 3,632,79J 4,095,443 5,217,355 1,963,00I intenance 1,811,850 3,307,681 2,792,798 3,535,443 4,377,355 963,000Laboratory fees 560,000 560,000 840,000 560,000 840,000 1,000,Aa

TOWl _ _I_ 3401,74C 23, 875 17,087,7 24,7%408 3253Z443 18,520,0Overheads 1,410,261 4,255,031 2,562,718 3,713,761 4,879,866 1,852,000

Contingencies 1,880,348 5,673,375 3,416,958 4,951,682 6,506,489 370,- Gnd Tohi (Flp) i22,341 3k25K281 23086,4865 3,23,51 43Wk1M7U 2D,74Z

-a OTOW(UpIq) 12.1 3.3 2106 33.A4 43U 207Qa ndT.hdUSj _ 0.2 O."e 0.41 0. 078 0.3

Table 5.2-1 Estimated Operating Cost of the Prototype STP/SpTP

6. Recommendations

This technical study recommends the following for the proposed prototype STP/SpTP inProject 7:

(a) Adopt altemative C as pilot project;(b) Maynilad to avail of the 1.3M USD World Bank grant and allocate any

amount in excess of the grant amount from its Capital ExpenditureBudget for Y2007. An annual operating budget of about 27M PhP has tobe earmarked from the Operating Budget starting August Y2008;

(c) MWSS/MWSI to prepare the bidding documents for a design and build(D&B) contract to facilitate implementation of the project.

Protect 7 Prototype STP/SpTP8/17/2006

Pap 19 of 20

7. Other Issues and Concerns

The upgrading and rehabilitation of Project 7 Imhoff Tank, though advantageous, posesfew impacts on the environment during pre-engineering, construction and operationstages. Major issues and concerns, particularly social acceptability and trafficaccessibility, must be given due attention prior to implementation of the project.

7.1 Social Acceptability

Most of the residents in Project 7 belong to medium and high income groups. It is,therefore, important to have an inter-agency coordination and focus group discussions tobe able to address their concems, particularly on the entry of several vacuum tankers tothe facility. About 24 vacuum tankers are expected to enter the treatment facility daily.

7.2 Traffic Accessibility

Vacuum tankers, mostly 10 cum. capacity, might have difficulty in traversing the roads tothe facility considering that Road A is only about 5.5m wide and Alley, about 3.0m. It isalso worth to note that passenger tricycles ply this route all the time. In this case, thedesign capacity of the proposed treatment plant may not be maximized. A well-plannedseptage collection schedule must, therefore, be ensured to address the issue.

Project 7 Prototype STPlSpTP8/1712006

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concept design project 7 sewage and septage...

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