Water and Sanitation Studies for the City of Paraty, Brazil

Water Solutions Nancy Choi, Claire Kfouri, Hyo Jin Kweon, Eun Chu You Advisors: Prof. Harleman, Frederic Chagnon

Background on Paraty

• Municipal in the State of Rio de Janeiro – Area: 930 km2 – Population: 30,000 • Urban 15,000 • Tourist city: UNESCO World Heritage Site Candidate • Three main sections: – Historical downtown – “Upper” part of city – “Ilha das Cobras”

1 Water and Sanitation Service Coverage and Health Consequences

• Developing countries have prevalent health problems due to lack of water and sanitation. • Paraty’s service coverage: – 60% potable water; 12% sewerage connection • Water and sanitation-related diseases – 32% of all hospital admissions in Brazil – >100 diarrhea cases/month (443 diarrhea cases from 9/02 to 12/02) in Paraty – Include: diarrhea, typhoid, viral hepatitis A, cholera, dysentery, guinea worm disease

Drinking Water Supply System – City of Paraty

Pedra Branca

Caboclo

Paraty City ReservoirJabaquara Beach

2 Prob. 1: Drinking Water Quality

64% of Municipality’s water sources (21% of which were chlorinated) did not comply with drinking water standards. 24% of City’s chlorinated water did not comply.

Prob. 2: Heavily Contaminated Surface Waters • Jabaquara Beach: – Inadequate for primary • Perequecontact Riverrecreation and (e.g. Matheusswimming) River • Sewerinadequate– Adequate Stream, forfor secondary an open channelsecondary(e.g. wading, of contactsurface fishing, water and thatrecreation.hunting). transports wastewater from houses to Paraty Bay, has qualities of raw sewage.

3 Proposed Policy/City’s Needs

• Wastewater collection infrastructure and treatment plant – Limit pollution of rivers and beaches – Reduce risks to health – Improve aesthetics in the city. • Drinking water treatment plant – Removal of particulate matter by filtration – Effective disinfection

Cost Estimate for Improvements

• Criteria: – Population = 15,000; 3x increase in summer – Flow = 3 mgd (assuming 180 L/capita-day) • Wastewater treatment plant + infrastructure: – Total annual cost = Annual O&M + Amortized capital cost (20 years at 6 percent) = R$ 0.5 million • Drinking water treatment plant: – Conventional filtration or Direct filtration – Total annual cost = R$ 1 million

4 Cost vs. Willingness to Pay

• Cost for improvement: – R$ 32/household-month (w/o meter) – R$ 0.35/m^3 (w/ meter) • Willingness to pay (WTP): – WTP = current payment for existing services + bottled water + (min wage lost from sickness) = R$7+ R$36 (assuming 2L/capita-day) + (R$7/capita-day) = R$43 ~ R$50/household-month • Willingness to Pay > Cost for improvement

The Need for Infrastructure Development

Propose a design of a wastewater collection system for the Historical Center of Paraty, Brazil.

5 Design Considerations • High water table • Flat land • No vehicles • Roads in poor condition • No basements • Underground structures (water distribution system, telephone line, nonfunctional sewer collection system) • Recent Survey: 415 residential lots, 211 commercial lots, 6 vacant lots, and 66 other lots

Potential Collection Systems

• Conventional Gravity Sewers • Pressure Sewers • Vacuum Sewers • Small-diameter Gravity Sewers

6 System Criteria

• Expandable: Future collection additions • Economical: Low cost system • Adaptable: Flexible to seasonal fluxes • Simple: Ease of operation and maintenance

Design: Conventional Gravity Collection System

Gravity Sewer ‡ Wet Well ‡ Treatment Plant ‡ Outfall

7 Results

Construction Costs Non-Construction Costs Total Cost Label Quantity ($US) ($US) ($US)

Outlet 1 1,105 0 1,105

Manhole 22 29,433 0 29,433

Gravity Pipe 22 245,069 0 245,069

Total Cost: Base 275,606

Total Flow = 2 million liters/day = 0.8 cfs

Chemically Enhanced Primary Treatment

8 Treatment Process Steps Chemically Enhanced Primary Treatment Conventional Primary Treatment Grit Removal Clarification

Disinfection Bar Screen Optional Flocculent Injection Anionic/Cationic Polymer Typically 0.1-0.2 mg/L Coagulant Injection Removal Efficiencies Typically FeCl3 (30-40 mg/L) 100

60 ConventionalSecondary 40 SecondaryCEPT

Percent Removal (%) 0 TSS1 BOD2 TP3 TN4 FOG5 Pollutant Type

Jar Testing

9 Seawater: Coagulation Enhancement

Relative Removal Rates Removal Efficiencies 100 12090 10080 70 80 Conventional 60 TSS 6050 BODCEPT 4040 FerricSecondary Chloride 30 20 20 Percent Removal (%) Percent Removal (%) 100 0 TSS BOD TP TN FOG Conv. Sec.PollutantCept Type HK Treatment Type

Seawater: Case study and Method

• Inspired by the Hong Kong Stone Cutter’s Island Wastewater treatment plant • Mg+2 ions replace Fe+3 to interact with negatively charged wastewater particles and form a solid precipitate. • In Paraty, jar test were conducted to test efficiency of SS, COD, and turbidity removals using seawater.

Relative Removal Rates

100 90 80 Flow Rate 3.7 m3/sec Influent BOD 156 mg/L 70 SOR 66 m/d Effluent BOD 39 mg/L 60 TSS 50 BOD Ferric Chloride 10 mg/L Influent TSS 200 mg/L 40 Ferric Chloride 30 Seawater 20% Effluent TSS 32 mg/L 20

Percent Removal (%) Anionic Polymer 0.1 mg/L 10 0 Conv. Sec. Cept HK Treatment Type

10 Results

RemovalRelativeCOD RelativeEfficiencies Removals Turb. SS removal with Removal with 10 varied andrates Rates 15% SW Seawater 80 80 706080 7070 6050 6060 Nono SW SW 504050 no SWCOD 50 0.50.5 % %SW SW 403040 0.5 % SSSW 3030 11% % SWSW 2030 2 % SWTurb 2020 22% % SWSW 10 1010 Percent Removal SS Percent Removal COD Percent Removal Turb 00 Removal Efficiencies (%) 0 00 0 10 30 2020 30(10)303030 30(15)404040 40(10)505050 40(15)606060 Ferric FerricChlorideFerricFerric ChlorideChloride Chloride mg/L and(mg/L) (mg/L) (Seawater %)

Seawater as an economic coagulant ? • Seawater is responsible for 20% increases in removal efficiencies of SS, Turbidity and COD at the same FeCl3 concentration

• Significant reductions in required volume of FeCl3 • Ideal for treatment plants with easy access to the ocean • Easier handling and storage requirements compared to other chemical coagulants • More research is needed on a pilot test scale but data from this project is positive. • Hong Kong, Norway, San Diego and Boston examples.

11 CEPT & Disinfection

• Why does CEPT efficiently and economically produce a disinfected effluent? – Quality • Lower coliform concentration in the effluent from CEPT settling tank – Cost • Lower amount of a disinfection agent required

Disinfection - Chlorine

• Disinfection & Effects of Seawater • ChlorineAddition on Chlorination Process – Most commonly used throughout the world – Inexpensive equipment and operation – Easy to apply and measure – DBP : THMs, AHHs

12 Disinfection - Alternatives

• Peracetic Acid (PAA) – Solution containing acetic acid, hydrogen peroxide, peracetic acid, and water – Efficient bactericide and virucide – Not influenced by pH – Short contact time – No formation of DBPs – Biodegradable Products : Acetic Acid • Ozone • UV Radiation

Disinfection – Paraty, Brazil • Coliform removal efficiency by chlorine was higher than that by peracetic acid.

10000000

Total 1000000 Fecal

100000

10000

1000 MPN/100ml

100

1 Initial Before PAA 5ppm PAA 10ppm PAA 15ppmPAA 20ppm Cl2 20ppm disinfection

13 Disinfection – Deer Island

Fecal Coliform Reduction - Ferric Chloride 20mg/L 1000000 No Additional Seawater 1% Additional Seawater 100000 5% Additional Seawater

10000

1000 MPN/100ml 100

1 Raw Blank Cl2 0ppm Cl2 5ppm Cl2 10ppm

Disinfection - Results

• Effect of seawater addition – Reduced coliform level in the effluent from CEPT

• Disinfection is essential for the WWTP.

14 Conclusions

• Wastewater infrastructure and treatment and drinking water treatment for the city. • A conventional gravity collection system is a feasible solution because of: – Relatively low costs – Simple operation and maintenance – Ease of expandability to future connections – Adaptability to seasonal changes • Chemically Enhanced Primary Treatment is the recommended treatment alternative for Paraty. • Seawater addition is a promising coagulation enhancement mechanism. • Seawater addition improves the rate of coliform removal. • Need to consider the use of PAA as an alternative disinfection agent

Thank You • Professor Donald Harleman • Frederic Chagnon • Dr. Ricardo Tsukamoto

QUESTIONS ?