project 7 sewage and septage treatment plant · 2016. 7. 15. · treatment mixed sewage...

Environmental Management Plan

Maynilad Water Services, Inc.

PROJECT 7 SEWAGE AND SEPTAGE TREATMENT PLANT PROJECT DESCRIPTION

MWSS received Technical Assistance (TA) financing from the World Bank

in 2005 to partially update their Water Supply Master Plan and to prepare a comprehensive Master Plan for Sewerage and Sanitation for its service area to the year 2025. The 2005 Master Plan proposed a decentralized small-bore sewerage approach and 16 new regional combined STP-SpTP’s, utilizing anaerobic biological treatment.

Combination sewage-septage treatment plants are common in the US (25%

of the US population have septic tank) and Australia, with septage to sewage portions usually less than 5%. One combined plant in Greece treats up to 40% septage with sewage. The advantages of combined sewage-septage treatment plants include I) Possible revenue for the treatment plant from independent haulers, ii) Use of excess treatment plant capacity maximum utilization of vacuum trucks, iii) Availability of a legitimate septage disposal site for independent haulers, and iv) Regional centralization of waste treatment facilities to name a few.

The MWSI Project 7 Communal Septic Tank is conceived for a proposed

protoype Sewage-Septage Treatment Plant (STP-SpTP) in 11 Road A, St Anthony Village, Quezon City which drains 45.6 ha. Of sewerage reticulation. It was selected due to a number of advantages, including a) site is in MWSI’s area b) Project 7 currently has a poorly operating treatment system the pollutes Culiat Creek c) The site area consists of about 1300 sq.m. d) There are no informal settlers on the site e) The site is government owned f) there are significant numbers of septic tanks in adjacent areas to draw septage g) access road is reasonable and trucks regularly come and go from the site h) the site is close to MWSI offices in Balara for monitoring, and I) sewage flow is something less than about 2 MLD.

The process design consist of an anaerobic (UASB) – aerobic (SBR)

biological treatment plant. Other process components would include possible reuse of the imhoff tanks for balancing, new sewage inlet works, a septage acceptance area, biosolids dewatering building and equipment, new chlorination disinfection system and contact tank, and odor control. The process will used 10% septage (240 m3/d), anaerobic-aerobic biotreatment. Theoretically, effluent from the proposed STP/SpTP not only meets the required standard specified in DENR AO 35, but should surpass the prescribed effluent water quality at all times. BOD5, COD and TSS concentrations are expected to decrease to 22 mg/l, 72 mg/l and 30 mg/l, respectively, after treatment. Applying mass balance analysis for all systems

E1288v10

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized

Pub

lic D

iscl

osur

e A

utho

rized



shows that processing 2,400cmd of sewage + 240cmd of septage will result to about 2,393cmd of treated wastewater, 103cmd biosolids, and 144cmd screened and degrited wastes. Biomass produced daily for possible reuse as soil conditioner contains about 99kg of BOD5 and 660kg TSS. Figure 1-1 presents the mass balance flow diagram for the proposed prototype STP/SpTP.

In SpTP, the estimated overall removal efficiency in terms of BOD, COD and TSS are 93%, 94% and 97%, respectively. However, treatment efficiency in STP is lower with approximately 80% for BOD, 80% for COD, and 85% for TSS. Dilution of primary effluent with screened sewage and absence of pre-aeration in the system results to further decrease in concentration of pollution loads causing lesser amount of micro-organism in the reactor. Table 1-1 summarizes the theoretical performance of the STP-SpTP.

Project 7 would help MWSI better utilize their current fleet of 32 septic tank pump out trucks ( includes 7 Mobile Dewatering Units). MWSI estimated that the current average for truck trips to Dagat-Dagatan STP-SpTP is about 1.2 or 257 m3 septage/day. At that frequency, the number of 5 m3 septic tanks desludged annually (300days/year) is about 15,700.

Project 7 could potentially increase the number of trips per day per truck to a

treatment facility to 1.5 (estimate by MWSI). At that frequency, the number of 5 m3 septic tanks desludged annually (300 days/year) would be about 19,500 (24% increase), with the septage delivered being about 321m3/day (25% increase). A more detailed traffic/septic tank pumpout study would be required to fully verify the effect of adding Project 7.

Another point worthy of note is that West Quezon City (QC) has a high

sanitation target for MWSI by the year 2021. A STP-SpTP in West Quezon City would be well placed to help deliver on this target.

The Manila Third Sewerage Project (MTSP) – Global Environmental Facility

(GEF) proposed prototype STP-SpTP will likely be the first of many similar decentralized sewerage and treatment plants if the 2005 Master Plan is implemented. Sixteen regional STP-SpTP’s were proposed to be operating by 2025 to address the most serious of the pollution hot spots in the MWSS service area. The fact that the proposed Project 7 site, one of about 1,300m2 , can support both 2.4 MLD of sewage, plus up to 15% septage (or 360 m3/d) also contributes to the replication concept around land-scarce Metro Manila

Environmental Management Plan Figure 1.1 Mass Balance Flow Diagram


REUSE(SOIL CONDITIONER)

CENTRIFUGE

AEROBIC DIGESTER

EQUALIZATION TANK

SBR

EQUALIZATION

TANK

BAR SCREEN

BAR SCREEN

SBR

DISCHARGE TO CULIAT CREEK

F I L T R A T E

W A

S T

E

S L

U D

G E

CHLORINE

CONTACT

TANK

W A S T E S L U D G E

Cl2

GRIT CHAMBER

S C

R E

E N

E D

& D

E G

R I T

E D

S E

P T

A G

E

SEPTAGE

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Raw SeptageQ, cmd 240

BOD5 , mg/l 2,752COD, mg/l 20,263TSS, mg/l 35,650

BOD5 , kg/d 660TSS, kg/d 8,556

Screening & DegritingQ, cmd 216



CentrifugeQ, cmd 158.35


Raw SewageQ, cmd 2400

BOD5 , mg/l 106COD, mg/l 246TSS, mg/l 88

BOD5 , kg/d 254TSS, kg/d 211

ScreeningQ, cmd 2280



Effluent DAO 35Q, cmd 2393.06 -

BOD5 , mg/l 22 50COD, mg/l 72 100TSS, mg/l 30 75

BOD5 , kg/d 52 -TSS, kg/d 72 -

M ass Balance ValueInf luent,cmd 2640.00Effluent,cmd 2393.06Biosolid,cmd 102.93

Screen&Grit,cmd 144.00

BOD,kg/d 99.14TSS,kg/d 660.49

Biomass

Equalization

Q, cmd2658.96

BOD5 , mg/l

109

COD, mg/l361

TSS, mg/l201

BOD5 , kg/d

291

TSS, kg/d

535

SBR

Q, cmd2658.96

BOD5 , mg/l

22

COD, mg/l72

TSS, mg/l30

BOD5 , kg/d

58

TSS, kg/d

80

SBRQ, cmd 541.37

BOD5 , mg/l 193COD, mg/l 1,277TSS, mg/l 1,283


EqualizationQ, cmd 541.37

BOD5 , mg/l 963

COD, mg/l 6,383

TSS, mg/l 8,556

BOD5 , kg/d 521

TSS, kg/d 4,632

DigesterQ, cmd 162.41

BOD5 , kg/d 156

TSS, kg/d 1,042


CENTRIFUGE

AEROBIC DIGESTER

EQUALIZATION TANK

SBR

EQUALIZATION

TANK

BAR SCREEN

BAR SCREEN

SBR


F I L T R A T E

W A

S T

E

S L

U D

G E

CHLORINE

CONTACT

TANK


Cl2

GRIT CHAMBER

S C

R E

E N

E D

& D

E G

R I T

E D

S E

P T

A G

E

SEPTAGE

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control


CENTRIFUGE

AEROBIC DIGESTER

EQUALIZATION TANK

SBR

EQUALIZATION

TANK

BAR SCREEN

BAR SCREEN

SBR


F I L T R A T E

W A

S T

E

S L

U D

G E

CHLORINE

CONTACT

TANK


Cl2

GRIT CHAMBER

S C

R E

E N

E D

& D

E G

R I T

E D

S E

P T

A G

E

SEPTAGE

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Odour Control

Raw SeptageQ, cmd 240













Raw SewageQ, cmd 2400









Effluent DAO 35Q, cmd 2393.06 -

BOD5 , mg/l 22 50COD, mg/l 72 100TSS, mg/l 30 75

BOD5 , kg/d 52 -TSS, kg/d 72 -

M ass Balance ValueInf luent,cmd 2640.00Effluent,cmd 2393.06Biosolid,cmd 102.93

Screen&Grit,cmd 144.00

BOD,kg/d 99.14TSS,kg/d 660.49

Biomass

Equalization

Q, cmd2658.96

BOD5 , mg/l

109

COD, mg/l361

TSS, mg/l201

BOD5 , kg/d

291

TSS, kg/d

535

SBR

Q, cmd2658.96

BOD5 , mg/l

22

COD, mg/l72

TSS, mg/l30

BOD5 , kg/d

58

TSS, kg/d

80

SBRQ, cmd 541.37

BOD5 , mg/l 193COD, mg/l 1,277TSS, mg/l 1,283


EqualizationQ, cmd 541.37

BOD5 , mg/l 963

COD, mg/l 6,383

TSS, mg/l 8,556

BOD5 , kg/d 521

TSS, kg/d 4,632

DigesterQ, cmd 162.41

BOD5 , kg/d 156

TSS, kg/d 1,042

Table 1.1 Theoretical Performance of Proposed STP-SpTP


Raw Septage

Equalization (Pre-aeration)

After SBR Treatment

Mixed Sew age Equalization

After SBR Treatment

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

DAO 35

Septage Treatment Plant Sewage Treatment Plant

Parameter Unit

2.0 MAJOR IMPACTS AND MITIGATING MEASURES Impacts have been identified during construction and operation as shown below:

2.1 During Construction a) Increased noise level in the vicinity. The noise level will increase temporarily during the construction due to piling activity. Noise level from piling activity is estimated at 75-110 dBa measured at 5 to 40 m distance. Close supervision of the construction will be undertaken to minimize indiscriminate noise production from construction activities. In addition, temporary wall barriers will be placed to reduce noise level. Nighttime pile driving will not be allowed unless necessary.

b) Increased air (dust) pollution. Air pollutants such as dust, Sox, Nox and particulates can be prevented and minimized by regular watering/sprinkling of roadway during dry and windy season.

c) Open excavation may cause accidents. To prevent accidents during construction, barricades and steel plates cover will be provided to open excavations during non-working time.

d) Volume of spoils or excavated materials. Excess excavated materials must be immediately removed from the site and dumped in designated disposal site in a manner that would not obstruct the flow of traffic or jeopardize the safety of motorists.

2.2 During Operation




a) Increased noise level in the vicinity. During plant operation, noise generated from the equipment is minimal since the equipment are housed in concrete buildings. Concrete walls of building will serve as sound barriers. b) Deterioration of surrounding air quality due to odor. Odor generated during the transfer of septage from the hauling trucks to the sludge holding tanks of the treatment plant will be mitigated by the odor treatment facility installed in the treatment plant. The odor treatment facility will be designed composing of air suction fans, activated carbon absorption towers and forced ventilation systems. All equipment are also housed inside the buildings with double walls and provided with ventilation. Air emission quality within the vicinity will be monitored.

c) Traffic congestion along the main and access roads. Road traffic due to incoming and outgoing trucks will be mitigated with close observance of traffic rules and regulations within the STP complex. Traffic rules, such as prohibiting septage trucks from parking on major roads leading to the treatment plant and delivery of septage during off-peak hours must be observed. Traffic officers must be assigned to handle traffic on all access roads in the vicinity of the treatment plant. e) Deterioration of public health. Public health of residents in the vicinity might be affected by the change in the air quality. The chances of adverse changes in air quality would be very slim, since mitigating measures have been provided such as odor control and regular monitoring. In addition, MWSI shall keep the plant site clean and orderly to prevent malodor and flies. A regular health check will be conducted on nearby residents. A medical station is provided within the complex to safeguard the health of the residents and the workers as well. f) Flooding during high monsoon rains or typhoon

The flooding problem due to its low elevation will be mitigated with the

provision of sufficient drainage system in the plant area.

3. ENVIRONMENTAL ENHANCEMENT PROGRAM



MWSI will implement the following environmental enhancement program in order to ensure the protection of the receiving water and the atmosphere. 3.1 Supervision and Monitoring. During construction, MWSI will ensure that the construction is carried out according to the detailed design and Bid Documents/Contract Documents (BD/CD) and contractors will follow the MWSI Safety Code (Chapter 5, see attachment). Contractors will also post an All Risk Performance Bond.

3.2 Environmental Monitoring Activities

3.2.1 Air Quality and Noise Level Monitoring

MWSS will monitor the air pollutants level such as total suspended particulates (TSP), sulfur dioxide (SO2), and nitrogen oxides (NOx) and noise level once a month. Three (3) stations as identified in Figure 3.2.1 located at 10 m, 30 m and 50 m are the designated sampling site. When the level of air and noise fall above the limits, immediate action will be undertaken by MWSI. Noise level should not be allowed to exceed 65 decibel at 10 m distance from the plant.

3.2.2 Water Quality Monitoring

A plant operation manual will be made by the winning contractor that details the operation and maintenance of each facility in the STP. In addition, MWSI shall also conduct routinary and periodic water quality monitoring of septic tanks and at the STP. Table II.1 shows the parameters to be tested, frequency of sampling and location.

Receiving water shall also be monitored and sampling stations shall be selected.

3.2.3 Odor Monitoring

MWSI shall conduct weekly monitoring at 10 m, 30 m and 50 m from the source of odor as shown in Figure 3.2.3. The sample collected shall be analyzed for the level of hydrogen sulfide and ammonia compounds.

3.3 Public Education and Information Campaign


During the construction and operation, a comprehensive public information campaign shall be conducted within the vicinity of Dagat-Dagatan area. Main objective is to educate and inform the people about the significance of a septage treatment plant to the environment. Public education will also tackle the roles of each individual in the protection of our environment, the safeguard of health and the risk involved.

Figure 3.2.1 Noise Monitoring Stations in Project 7 proposed SSpT Plant

30 m

50 m

10 m

Figure 3.2.3 Odor Monitoring Stations in Project 7 proposed SSpT Plant



30 m

50 m

10 m

Table I. Monitoring Parameter and Frequency for Project 7 Sewage

and Septage Treatment Plant

Test Items Influent Effluent Excess Sludge

Dewatered Sludge




Routine Test Temperature Daily Daily Color/Odor Daily Daily Transparency Daily Daily pH Daily Daily Daily DO Daily SV Periodical Test COD Once/Week Once/Week BOD Once/Week Once/Week SS Once/Week Once/Week Once/Week VSS Once/Week Once/Week TS Once/Week Once/Week Once/Week Once/Week TVS Once/Week Once/Week Once/Week Once/Week TDS Once/Week Once/Week SM Once/Week Oil and Grease Once/Week Once/Week Alkalinity Once/Month K-N Once/Month Once/Month Once/Month NH4-N Once/Month NO4-N Once/Month T-P Once/Month Once/Month Once/Month PO4-P Once/Month Detergent/Surfactant Once/Week Phenol Once/Month Once/Month Heavy Metals Once/Month Total/Fecal Coliforms Once/Week Once/Week



ENVIRONMENTAL MONITORING PLAN

Project Activities Parameters Location Frequency Responsibility

During Construction Dust Construction Site Daily MWSI Noise Construction Site Daily MWSI Air Pollutants Construction Site Daily MWSI Spoil Materials Construction Site Daily MWSI Traffic Construction Site Daily MWSI Open

Excavation Construction Site Daily MWSI

Erosion/Siltation Construction Site Daily MWSI Operational Phase Dust Treatment Plant Monthly MWSI Noise Treatment Plant Monthly MWSI Air Pollution Treatment Plant Monthly MWSI Odor Treatment Plant Daily MWSI Wastewater

Effluent Quality Treatment Plant Weekly MWSI

Health and Sanitation

Treatment Plant Daily MWSI



Public information campaign shall be in the form of organized

lectures, distribution of materials and site visits. In this way, the public will be have an in-depth understanding of the treatment plant.

4. CONTINGENCY PLAN

Contingency plan covers the different measures to be undertaken by MWSI in case of the following incidents:

4.1 Accidental Septage Spill

Vacuum truck containing 0.5% hypochlorite solution shall be used to flush septage to the drainage system. The area shall also be inspected for any occurrence of septage related diseases for a period of one month. The disinfectant, 0.5% hypochlorite solution, shall be prepared at the SSTP site using powder chemical mixed in the cleaned vacuum cars.

4.2 Foul Odor Emission at the STP

MWSI shall immediately investigate. The sewage and septage treatment operation shall also be stopped until the source of odor has been identified and controlled.

4.3 Occurrence of Septage Related Epidemic in the Vicinity

The STP-SpTP operations shall be immediately stopped when related health epidemics are reported. MWSI shall then conduct a complete examination of the receiving water, as well as, the adjacent deepwells for any contamination. Medical doctors and health workers shall be brought to the site to investigate the occurrence of disease. It must also be reported to the Department of Health.

In case of deterioration of effluent water quality discharged to waterways, MWSI shall conduct a complete assessment of the viability and functionability of all the unit processes or equipment immediately. Any damaged parts shall be repaired or replaced immediately.



5. ENVIRONMENTAL MANAGEMENT PLAN

Impact

Description Mitigation/Enhancement Institutional

Commitment Schedule

During Construction 1. Increased noise level

Close supervision of the construction will be undertaken to minimized indiscriminate noise production from construction activities Temporary wall barriers will be placed to reduce noise level Nightime pile driving will not be allowed unless necessary

MWSI

MWSI

MWSI

During construction During construction During construction

2. Increased air (dust) pollution

Air pollutants such as dust, TSP,NOx, Sox can be prevented and minimized by regular watering/sprinkling of roadway during dry and windy season

MWS During construction

3. Open excavation may cause accidents

To prevent accidents during construction, barricades and steel plates cover will be provided to open excavations during non-working time/hours

MWS During construction

4. Excess spoils/excavated materials

Excess excavated materials must be immediately removed from the site and dumped in designated disposal site in a manner that would not obstruct the flow of traffic or jeopardize the safety of motorists

MWSI During construction



Impact

Description Mitigation/Enhancement Institutional

Commitment Schedule

During Operation Phase 1. Air and Noise Pollution

MWSI will monitor the air pollutants level such as TSP, Sox, NOx, and noise level once a week. Three designated stations will be identified, 10, 30 and 50 meters

MWSI Once/Month

2. Increased noise level in the vicinity

Noise generated from the plant equipment is minimal since the equipment are housed in concrete buildings Concrete wall of building will serve as sound barriers

MWSI During operation

3. Generation of odor

Odor treatment facility will be installed in the treatment plant to mitigate odor generated during transfer of septage from the hauling trucks to the sludge holding tanks All equipments are housed inside the building with double walls and provided with ventilation Air emission quality within the vicinity will be monitored

MWSI MWSI MWSI

During operation During operation During operation

4. Deterioration of water quality

Effluent wastewater from the treatment plant will be monitoreddaily and should meet the effluent standards set by the DENR


5. Deterioration of public health

MWSI shall keep the plant site clean and orderly to prevent malodor and flies Regular health check will

MWSI MWSI

During operation During operation



be conducted on nearby residents. A medical station will be provided within the complex to safeguard the health of the residents and workers as well

6. Flooding during high rains or typhoon

The flooding problem due to its low elevation will be mitigated with the provision of sufficient drainage system in the plant area
