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Water Reuse in San Mateo: A Biosystems Engineering Capstone Design
- 1. Senior Design: Water Reuse in San Mateo Biosystems Engineering Capstone Design Clemson University Elena Miyasato, Kylie Bednarick, Lillian Kome, and Amanda Dara
- 2. Outline ● Introduction ○ Background ○ Goals and Scope ○ Constraints and Considerations ● Literature Review ○ Water Recycling Background ○ Water Reuse in San Mateo ● The Process ○ Treatment Processes, Designs, and Results ● Implementation ○ Distribution and Economics ○ Public Outreach ● Final Thoughts Hetch Hetchy Reservoir
- 3. Background Client: The City of San Mateo, California The Current Situation: The Opportunity: Design a recycled wastewater treatment process
- 4. Recognition of Problem ● Environmental ○ Climate change → Decrease in water security ■ Extreme droughts ■ Snowpack that feeds reservoir is shrinking ● Human ○ Current water usage is unsustainable ○ Growing population → Increase in demand
- 5. Goal and Scope Goal: Design a water recycling process that can produce reusable water from the liquid effluent of the San Mateo WWTP Scope: ● Meet water quality standards ● Determine uses for recycled water ● Determine uses for by-products ● Analyze economic viability ● Promote positive perception of recycled water
- 6. Fundamentals of Sustainability Environmental ● Decrease the demand of water sourced from Hetch Hetchy ● Limit wastewater effluent into San Francisco Bay Social ● Improve the perception of wastewater reuse ● Increase confidence in water security for future generations Economic ● Cost effective water resource ● Affordable to consumer
- 7. Considered Constraints Design Team Constraints: ● Time ● Modeling Resources Process Constraints: ● Water reuse requirements ● Economics of construction & distribution ● Space ● Logistics
- 9. Water Recycling Water recycling: The process of treating wastewater to the extent that it can be reused for beneficial purposes ● Uses liquid effluent of municipal wastewater treatment Recycled water quality: ● Non-potable ○ Primary treatment ○ Secondary treatment ○ Tertiary treatment ● Potable ● Purple pipes used for non-potable recycled water
- 10. Recycled Water Usage ● World Leader: Israel ○ Recycles over 85% of its wastewater ○ Used for agricultural irrigation ● USA Leader: Florida ○ Used for landscape & golf course irrigation ● California has been using recycled water since 1912 ○ Current top uses: ■ 40% Agricultural irrigation ■ 20% Landscape and golf course irrigation ■ 12% Groundwater recharge
- 11. Water Quality Standards in CA ● Title 22: California Code of Regulations ○ Defines 3 types of recycled water based on level of treatment ■ Disinfected Secondary-2.2 ■ Disinfected Secondary-23 ■ Disinfected Tertiary ● “Filtered and subsequently disinfected wastewater” that meets given disinfection criteria ○ Chlorine contact time and total coliform bacteria ○ Defines uses for each type of water
- 12. Disinfected Tertiary Water Uses ● Disinfected tertiary recycled water can be used for all non-potable uses in California ○ Unrestricted irrigation ■ Food crops, pastures, golf courses, parks, school grounds, etc. ○ Industrial & commercial processes ○ Cooling towers, evaporative condensers, etc ○ Decorative fountains & ponds ○ Flushing toilets ○ Artificial snow ○ Fire fighting and control
- 13. San Mateo’s Recycled Water Demand ● San Mateo population: 100,023 (2012) → 104,750 (2017) ● The San Mateo Water Market Survey ○ Estimated Recycled Water Demand in 2012: ● Concluded recycling process should produce 4 mgd Usage Number of Customers (Sites) Average Annual Demand [AFY] Estimated MDD [MGD] Urban Irrigation 95 1,231 2.3 Commercial/Industrial 9 31 0.04 Total 106 1,263 2.34
- 14. Influent Water Parameters Mark Burke: Laboratory Analyst, City of San Mateo WWTP ● August 2017- August 2018 WWTP Effluent Values ● Salinity: 2,000 ppm (mg/L) ● TSS: 7.3 mg/L Ammonia [mg/L] Total Kjeldahl Nitrogen [mg/L] Nitrate [mg/L] Nitrite [mg/L] Dissolved Reactive Phosphate [mg/L] Total Phosphorus [mg/L] Nickel [ug/L] Copper [ug/L] Cyanide [ug/L] Mercury [ug/L] Average 32.68 35.58 2.34 0.90 3.72 3.45 5.03 5.95 0.74 0.00 Max 43.00 51.90 18.00 2.50 31.00 5.60 21.00 8.50 2.10 0.01
- 15. Effluent Water Target Parameters Specific goal: Produce disinfected tertiary water that can be used for urban irrigation and cooling towers Bacteria TSS TDS Ammonia Phosphorus Nitrate Max Level 2.2 MPN/100 mL 1-4 mg/L 100-400 mg/L 5 mg/L 5 mg/L 10 mg/L Reasons for tracking -Title 22 Standard (required) -Harmful to processes & environment -Salt harmful to plants -Can cause corrosion -Affects chlorination step -Helpful nutrient -Inhibits corrosion -Can cause eutrophication in water bodies -Helpful Nutrient -Inhibits corrosion -Can cause eutrophication in water bodies
- 16. The Process
- 18. Overview of Process Process Objectives: 1. Remove suspended solids (TSS) 2. Reduce concentration of dissolved chemicals and salts (TDS) 3. Disinfect effluent Our Components: 1. Granular Media Filtration (GMF) → Remove TSS; serve as pretreatment for NF 2. Nanofiltration (NF) → Reduce TDS (salts, organics, and microorganisms) 3. Chlorination → Ensure disinfection
- 19. 1. Media Filtration Considerations ● Purpose: removes suspended solids by passing water through a porous medium ● Selection: Dual-media Filtration ○ higher flow rate ○ longer filter time ● 2 operations states ○ filtration and backwash ● Design Factors: layer depth, filtration rate, grain size and grain size distribution, filter area Anthracite coal Silica sand Gravel
- 20. 1. Granular Media Filtration: Design Filter Rate 4 gal/ft2/min Backwash Rate ~20 gal/ft2/min Water Depth ~1-6 ft Sand Anthracite Depth 6 in 1.5 ft Grain Size 0.5 mm 0.98 mm
- 21. Granular Media Filtration: Design Number of Filters: Online 5 Number of Filters: Standby 3 Single Filter Dimensions 16’ x 12.5’ Single Filter Area 200 ft2 Filter Run Time 30-48 hours Backwash Time 20-30 min Filtration Single Filter
- 22. Granular Media Filtration: Design Backwash Number of Filters: Online 5 Number of Filters: Standby 3 Single Filter Dimensions 16’ x 12.5’ Single Filter Area 200 ft2 Filter Run Time 30-48 hours Backwash Time 20-30 min
- 23. 1. Granular Media Filtration: Design Equations
- 24. 1. Granular Media Filtration: Results ● Influent Flow Rate: 5.56 MGD ● Effluent Flow Rate: 5.38 MGD ○ Water Loss: 4% to backwash Constituent Bacteria TSS* Turbidity* TDS Ammonia Phosphorus Nitrate Influent Concentration 36.7 MPN/100 mL 7.3 mg/L 5.62 NTU 2000 mg/L 32.68 mg/L 3.45 mg/L 2.34 mg/L Effluent Concentration 12.8 MPN/100 mL 1.46 mg/L 1.12 NTU 2000 mg/L 32.68 mg/L 3.45 mg/L 2.34 mg/L *Goal met
- 25. 2. Membrane Filtration Considerations ● Purpose: removes total dissolved solids ○ Total dissolved solids (TDS) includes minerals, salts, metals, cations, and anions ○ Drinking water: 500 mg/L TDS (EPA), Ocean water: ~35,000 mg/L TDS ● Options: Microfiltration, Ultrafiltration, Nanofiltration, Reverse Osmosis ● Selection: Nanofiltration (NF)
- 26. 2. Nanofiltration: Design ● Similar to RO in concept and operation ○ Difference: monovalent ions ● Applications include: softening, removal of color, pharmaceuticals, food production ● Spiral-wound vs. Hollow tube configurations
- 27. Nanofiltration: Design ● Pressure Vessels ○ PVC ○ 4 in x 85 in ○ 2 filters per vessel ● Using 4 MGD permeate flow rate → Need 2000 filters and 1000 vessels Process Specifications Number of filters 2000 Number of pressure vessels 1000 Number of Skids 125 Flux 30.5 GFD Membrane surface area 131,200 ft2 Manufacturer Specifications Manufacturer Applied Membranes Inc. (AMI) Model number M-N4040A9 Dimensions 4” x 40” Salt rejection rate 90% Permeate flow rate 2000 GPD (gal/day)
- 28. 2. Nanofiltration: Results ● Influent Flow Rate: 5.38 MGD ● Effluent Flow Rate: 4.0 MGD ○ Water Loss: 25% to brine waste stream ● Assumed TDS is equivalent to salinity Constituent Bacteria* TSS TDS* Ammonia* Phosphorus* Nitrate* Influent Concentration 12.8 MPN/100 mL 1.46 mg/L 2000 mg/L 32.68 mg/L 3.45 mg/L 2.34 mg/L Effluent Concentration ~0 MPN/100 mL 0 mg/L 241 mg/L 3.93 mg/L 0.415 mg/L 0.283 mg/L *Goal met
- 29. 3. Disinfection Considerations ● Purpose: Ensure water disinfection quality is met ○ Goal: Maximize contact time between agent and wastewater ● Disinfection Options: ultraviolet radiation (UV), chlorination, ozone ○ Chlorine options: chlorine (Cl2), sodium hypochlorite (NaOCl), chlorine dioxide (ClO2) ● Selection: Chlorine (NaOCl) Characteristic Chlorine Gas Sodium Hypochlorite Ozone UV Radiation Use as disinfectant Common Common Occasional Increasing rapidly Safety concern High Moderate to low Moderate Low Effectiveness as disinfectant Excellent Excellent Excellent Good Increases TDS Yes Yes No No Byproduct formation Yes Yes Yes No
- 30. 3. Disinfection: Sodium Hypochlorite ● Relative ease of handling ● Less corrosive than chlorine gas ● High particle penetration Title 22 requirement: ● Minimum CT of 450 mg-min/L ● Minimum 90 min retention time Residual chlorine is needed in water to prevent biofilms ● Target for residual chlorine: ○ Min: 0.2 mg/L ○ Max: 4 mg/L Characteristic Effect on Chlorine Consumption Ammonia Forms chloramines Nitrate Reduces effectiveness, produces trihalomethanes pH Affects hypochlorous acid equilibrium
- 31. 3. Plug Flow Chlorine Contact Basin Calculated: ● Total Volume: 1,250 m3 ● Retention time: 119 mins Structural Design Parameters: ● Length: 25 m ● Width of Channels: 2.5 m ● Depth: 5 m Influent = Effluent ● 4 MGD
- 32. Chlorination Equations Ammonia from NF: 3.93 mg/L = 2.307 x 10-4 mol/L HOCl: 2.307 x 10-4 mol/L NaOCl: 5.152 mg/L consumed by the ammonia From Title 22: ● CT = 450 mg-min/L ○ CT= Chlorine Residual x Contact Time From Design: ● Contact Time = 119 minutes ● Chlorine Required Residual = 3.785 mg/L NaOCl Dose : 8.937 mg/L
- 33. Process Effectiveness Summary Influent: 5.56 MGD of treated wastewater → Effluent: 4 MGD of disinfected tertiary water Constituent Influent Effluent Target (Max) Fecal Coliform Bacteria 36.7 MPN/100 mL 0 MPN/100 mL 2.2 MPN/100 mL TSS 7.3 mg/L 0 mg/L 1 - 4 mg/L TDS 2000 mg/L 249.8 mg/L 100-400 mg/L Ammonia 32.68 mg/L 0 mg/L 5 mg/L Phosphorus 3.45 mg/L 0.415 mg/L 5 mg/L Nitrate 2.34 mg/L 0.283 mg/L 10 mg/L
- 34. Waste Stream ● A brine waste stream will be produced by nanofiltration ○ Flow Rate: 1.38 MGD ● Possible disposal options ○ Disposal into surface waters w/ treated effluent ○ Evaporation ponds ○ Falling film evaporators ○ Spray dryers ○ Crystallization ○ Utilize the brine ■ Send to industry ● Used in production of chemicals, glass, paper, textiles, etc.
- 35. Implementation
- 36. Aerial Layout 2 1 3 GMF 1,600 sq ft Nanofiltration 4,500 sq ft Chlorination 2,400 sq ft 2 1 3
- 37. Distribution ● A new purple pipe distribution system would be required ● San Mateo Water Market Survey Cost Estimations Total Construction Cost $15,631,000 Total Project Capital Costs $25,401,000 Annual O&M Costs $342,000 Annualized Capital Costs $1,296,000 Total Annual Costs $1,638,000 Unit Cost $1,530/AF Pipeline System Diameter (in) Length (ft) 6 22,600 12 39,000 Total Length 61,600
- 40. Overall Cost Estimate Study of Californian Water Reuse Projects ● 4 MGD = 4,480.58 AFY ● Est. Cost per AF: $ 10,583.48 Funding Sources ● Water Rates from Consumers ● Water Recycling Funding Program $ 47,420,076.24
- 41. Public Outreach Public education is a key step towards increasing water recycling initiatives Public opinion: ● Unaware of the process ● Can be unfavorable because of health concerns Example of outreach solution: Brochure Goal: Provide a introduction to water recycling & increase favorability Audience: ● General public ● Potential customers ● Residents in areas where recycled water is used
- 42. Proposed Design Schedule - Gantt Chart 2019 2020 2021 2022 Feasibility Study Supplemental Studies Engineering Report Regulatory Approval Environmental Documents Institutional/Financial Efforts Public Outreach Preliminary Design Design Refinement Construction Operation
- 43. Final Thoughts ● Learning curve ● Network with industry partners and Clemson professors ● Engineering process → revisions! ● Dealing with real world problem ○ Think about the details
- 44. Acknowledgements We appreciate the guidance and expertise from the following people: Mark Burke, Laboratory Analyst for City of San Mateo WWTP Dr. Alessandro Franchi, Senior Supervising Engineer at Parsons Corporation Mike DiNapoli, Construction Project Manager at Jacobs Dr. Yann Le Gouellec, Assistant Director at Newport News Waterworks Deryk Daquigan, San Mateo Clean Water Program Manager Jay Witherspoon, Jacobs Clean Water Program Manager Sujit Ekka, Client Account Manager, Technical Leader Water Resources Environment Business Unit at AECOM. Jim Grant, Professional Engineer, EW2 Environmental Inc. Dr. Darnault and Jazmine Taylor, Senior Capstone Design Advisors
- 45. References Alexandrou, L. Meehan, B. Jones, O. (2018). Regulated and emerging disinfection by-products in recycled waters. Sci. of the Total Environment. 637:1607-1616 Asano, T., Burton, F., Leverenz, H., Tsuchihashi, R., Tchobanoglous, G. (2007). Ch6-11. Water Reuse: Issues, Technologies, and Applications. Metcalf & Eddy, New York. Bell, E., Stokes-Draut, J., Horvath, A. (2018). Environmental evaluation of high-value agricultural produce with diverse water sources: case study from Southern California. Environmental Research Letters. 13(2). California Health Laws Related to Recycled Water. (2001). Available at: https://www.eid.org/home/showdocument?id=458. Accessed 20 October 2018. California Water Service. (2015). 2015 Urban Water Management Plan. Retrieved From: https://www.calwater.com/docs/uwmp2015/bay/Mid-Peninsula/2015_Urban_Water_Management_Plan_Final_(MPS).pdf California Water Service. (2017). Notice of California Water Service’s Request to Increase Rates for the Cost of Capital Application. Retrieved from: http://www.cpuc.ca.gov/uploadedFiles/CPUCWebsite/Content/About_Us/Organization/Divisions/News_and_Outreach_Office/ PAO/CustomerN/2017-04%20CoC%20notice%20VIS.pdf CEPA. (2017). Water Recycling Funding Program: Municipal Wastewater Recycling Survey. California Environmental Protection Agency. Available at www.waterboards.ca.gov. Accessed 1 October 2018. City of San Mateo. (2007). Sustainable Initiatives Plan. San Mateo Sustainability Advisory Committee. Available at: https://www.cityofsanmateo.org/DocumentCenter/View/64497/Sustainable-Initiatives-Plan?bidId=) Ciuk Karlsson, S. (2015). Simulating Water and Pollutant Transport in Bark, Charcoal and Sand Filters for Greywater Treatment. Department of Energy and Technology, Swedish University of Agricultural Sciences, Uppsala, Sweden. EPA. (2012). Guidelines for Water Reuse. 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Victorian Government Department of Human Services. Hoeft, M., Propersi, M. (2013). San Mateo Recycled Water Market Survey Project. Technical Memorandum 0196-011. Retrieved from: https://www.cityofsanmateo.org/DocumentCenter/View/43625/Recycled-Water-FS---City-of-San-Mateo-Recycled-Water- Market-Survey?bidId= IMFA. (2016). Water Recycling Technologies in Israel. Israel Ministry of Foreign Affairs. http://mfa.gov.il/MFA/InnovativeIsrael/GreenIsrael/Pages/Water-recycling-technologies-in-Israel-29-Mar-2016.aspx. Accessed 3 October 2018. Ionics Inc. (1984). Electrodialysis-Electrodialysis Reversal Technology, Ionics Inc., Watertown, MA. Iorhemen, O. T., Hamza, R. A., & Tay, J. H. (2016). Membrane Bioreactor (MBR) Technology for Wastewater Treatment and Reclamation: Membrane Fouling. Membranes, 6(2), 33. http://doi.org/10.3390/membranes6020033 Khan, S. (2013). Drinking Water Through Recycling: The Benefits and Costs of Supplying Direct to the Distribution System. Report of the Australian Academy of Technological Sciences and Engineering, funded by the Australian Water Recycling Centre of Excellence through the Commonwealth Government’s Water for the Future initiative. Link: https://www.atse.org.au/Documents/Publications/Reports/Water/drinking-water-through-recycling-full-report.pdf 30 LeChevallier, Mark W, Au, Kwok-Keung & World Health Organization. Water, Sanitation and Health Team. (2004). Water treatment and pathogen control: process efficiency in achieving safe drinking water / Mark W. LeChevallier, Kwok-Keung Au. Geneva : World Health Organization. http://www.who.int/iris/handle/10665/42796 Liberti, L., Notarnicola, M., Petruzzelli, D. (2002). Advanced treatment for municipal wastewater reuse in agriculture. UV disinfection: parasite removal and by-product formation. Department of Civil and Environmental Engineering, Polytechnic University of Bari, Taranto, Italy. Moulden, J. (2014). States, Cities Get Creative About Recycling Water. 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California Agricultural Water Stewardship Initiative. Available at www.agwaterstewards.org. Accessed 28 September 2018. Sheikh, B., EBMUD Office of Water Recycling. (2000). WateReuse Association of California. Recycled Water Uses Allowed in California. Available at: www.watereuse.org/h2o. Sobotka, J. (1993). The Efficiency of Water Treatment and Disinfection by Means of Ultraviolet Radiation. Water Sci Technol. 1 February 1993; 27 (3-4): 343–346. doi: https://doi.org/10.2166/wst.1993.0372 Sramkova, M., Diaz-Sosa, V., Wanner, J. (2018). Experimental verification of tertiary treatment process in achieving effluent quality required by wastewater reuse standards. J. of Water Process Eng. 22:41-45. Sujak, S., Handani, Z. B., Alwi, S. R., Manan, Z. A., Hashim, H., & Shiun, L. J. (2017). A holistic approach for design of Cost-Optimal Water Networks. Journal of Cleaner Production, 146, 194-207. doi:10.1016/j.jclepro.2016.06.182 Tchobanoglous, G., Burton, F., Stensel, D. (2003). 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- 46. Thank you!
Editor's Notes
- Amanda
- Amanda Today we’ll be introducing our project to you, going through our literature review, and presenting our preliminary designs.
- Elena: The City of San Mateo has created a Clean Water Program out of their public works department in order to update and improve their aging sewer water collection and treatment infrastructure. They have hired Jacobs Engineering group to help manage this program. I had the opportunity to work on the Clean Water Program over the summer and was introduced to the program’s interest in diving deeper into the feasibility of water reuse implementation for the city. Currently, water is collected from the Hetch Hetchy Reservoir in the sierra nevada mountains and is sold to Cal water from the SFPUC. Cal Water distributes this water to the people of San Mateo. Their waste is then sent to the San Mateo Wastewater treatment facility and is treated to meet regulations required to dump the water back into the SF bay. So the opportunity for us is to design a treatment process that produces water that can be recycled. A few of the components that were discussed for San Mateo specifically is the lack of intense agriculture in the area, the disposal of salts in the waste stream of this treatment process and people’s perception toward recycled water. (The City of San Mateo is currently in the process of designing a new liquid treatment facility though because we do not know the effluent values of that process we scoped our process to follow the current liquids process since those were the parameters we were able to access.)
- The problem that our project combats is twofold. First, climate change is causing a decrease in water security across the globe. More specifically, California just came out of a historic 5 year drought, from 2012-2017, and continues to face localized drought. Additionally, as Elena mentioned, the HetchHetchy reservoir provides water to San Mateo. This reservoir is fed by a snowpack in the Sierra Nevada mountains, which is expected to decrease to half its size over the next 80 years. The second part of the problem is human consumption. Currently in the California, the water usage is often unsustainable. To add to that, the population is expected to grow, increasing the water demand. These are the issues that we are working to change. Amanda Pulling from a decreasing snowpack as the source water is unsustainable. This source might not be able to change, but the water practices CAN change, so that people are efficiently using water (reusing it!) looming environmental problem and room to improve sustainable water practices Climate change has been causing water scarcity throughout California. 2012-2017: historic 5 yr drought in California, and they still face droughts going forward As Elena mentioned, the HetchHetchy reservoir supplies San Mateo’s water. That reservoir is fed by a snowpack in the Sierra Nevada mountains, that is expected to decrease in size by a half over the next 80 years, due to climate change. Notes: “The Sustainability Advisory Committee is concerned about water supply and recognizes that less snowpack in the Sierras, a predicted effect from global warming, will result in a decreased water supply and necessitate changes in the consumption patterns of all stakeholders.” The hetch-hetchy reservoir is fed by a snowpack in the Sierra Nevada Mts. Due to a climate-change induced lack of snowfall, the snowpack is decreasing is size and reliability. -Over the next 80 years, the snow-water equivalence (the amount of water contained in a snowpack) is expected to decrease by ½. current water practices include over-use of rivers & other water sources
- Lillian: Our main objective is to design a process that can successfully produce usable water from San Mateo’s wastewater. The process will allow a portion of the city’s treated wastewater to be diverted from the San Francisco bay and reused throughout the city. In addition to designing the process itself, we also wanted to determine if water reuse in San Mateo is a viable option. As a part of that, we made sure our process could produce water that was safe and met all relevant water quality standards. We investigated the potential uses and demand for the water, and uses for the by-products of the process. We also conducted an economic analysis for our system. Finally, we explored ways to promote positive perception of recycled water. MAKE SURE TO ADDRESS DELIVERABLES
- Kylie: Throughout our project, we have focused on 3 aspects of sustainability. Environmentally, the team is looking to decrease the demand of water from hetchy and lower the amount of waste being released into the san Francisco bay. Some of our water may end up going to the bay, but it will be of a higher quality and won’t negatively impact that ecosystem. Socially, we wanted to address any misconceptions there are about using recycled wastewater and promote the practicality and overall safety of this process. In addition to this, we know there are a finite number of resources on this earth, and they’re only going to start running out with population growth, so we wanted to showcase a sustainable method for water resource management that can be used by future generations and for the benefit of future generations. For the economics side, we need this process to economically feasible and competitive with already existing sources for irrigation. No matter how sustainable the process, no one will buy water if it’s too expensive.
- Elena: In this design process we must consider many constraints. In terms of our deliverables we quickly came to the understanding of the limitations our design team were going to have in regards to our scope. The breadth of the project meant that we must consider the time, resources and expertise of our team. This meant that this process design would correspond to what the industry might consider a Design Proposal or 20% design. In industry, revision following each design phase would review and refine the working design till a 100% or final design is perfected. Regarding our process- our design constraints include the process effectiveness, economics of making the process and how it affects the consumers, the space needed, and operational logistics. Because this design would take place in California, we had our research cut out for us. The most important information we needed to find regarded the demand and perception of recycled water: is this even something that consumers would want? There is not much agriculture in the limits of San Mateo so where else would the recycled water be used? The Water treatment process it self: what needs to be done to get the influent water quality to meet standards to be recycled and what processes there are that are able to achieve such. The regulations for recycled water: what restrictions there are and how to match up the process to achieve a specific water quality with an application that actually would be used in San Mateo. And the background on the San Mateo water effluent that would serve as our influent parameters and decidedly affect the treatments we would need to use to meet the water quality standards.
- Lillian: Water recycling is also called water reclamation or water reuse Can also use stormwater While there are a few cases of producing water quality high enough to be used directly as potable water, indirect potable reuse is much more common. This is when high quality water is injected into the ground For example, since 1976, the Orange County Water District in California has been injecting highly treated recycled water into the aquifer to prevent salt water intrusion, while augmenting the potable ground water supply.
- Lillian People use it this way/why; tie into evidence it works for us, etc -the 80% makes up about 25% of their water supply -Other places with water scarcity such as arizona & australia also use water recycling, as well as place with good water supplies- Delaware has irrigated cropland with recycled water since 1970’s. -Diagram is the percentage of it’s wastewater that it recycles (vs. % of its water supply that recycled water makes)
- Lilian: Division 4, Chapter 3, titled Water Recycling Criteria, defines in Article 1 three different levels of recycling treatment Note that the definitions/regulations pertain to disinfection levels; a regulation for nutrients or salt levels is not given by Title 22
- Lillian - Title 22 provides a list of acceptable uses for tertiary recycled water. It can be used for all non-potable uses in CA. These uses include [list]. As I mentioned before, irrigation is the most common of these uses for recycled water in general.
- Kylie In order to justify creating a water reuse facility is was important to know that there was demand for the final recycled effluent. In 2013 San Mateo hired a consulting firm to conduct a water market survey to estimate where recycled water effluent could be used throughout the city. The results of this study identified around 106 potential customers, with would require a total Maximum Daily Demand of 2.34 MGD. A majority of the water is used in urban irrigation, which is water applied for landscaping and golf courses. The rest of the water would supply commerical/industrial cooling towers. An important note; mentioned earlier that most recycled water is used for ag irrigation, however there is little demand for that in San Mateo. For our design, the team came up with a goal production rate of 4 MGD to meet the current projected demand of recycled water as well as encourage new customers to enter the market.
- Kylie This shows the effluent water quality of wwtp, which we used as our influent values for our reuse process. Values were provided by Mark Burke, lab analyst. Values you see in table are measured regularly in the wwtp, and with those we were able to find an average and max values over the span of a year (2017-2018). the salinnity and TSS values are not tested for regularly, however they were provided by Mark and a nutrient report done on the wwtp. Mostly focused on ammonia, phosphate, nitrate Maybe mention here or before now that the effluent from the WWTP is 12 mgd -Lillian
- Kylie (Everything except bacteria are not standards, they are values based literature review about application to plants) This table shows the max values we were trying to reach by the end of our process. Title 22 defines the minimum allowable bacteria count for reusable water. We’re interested in tracking ammonia because of its effect on the Chlorination step; Phosphorus, Nitrogen, can contribute to eutrophication, but would be helpful for planthealth. TDS are nutrients concerned with plants since our water will be used for irrigation. In a moment we’ll discuss how we addressed each of these targets Say a sentence about the max bacteria level. Things in green are generally helpful to our uses but can become harmful in elevated levels Get specs on T22 bacteria for presentation TSS standard from book. P and N from https://extension.psu.edu/interpreting-irrigation-water-tests where N=10 mg/L is a drinking water standard https://www.hydro-int.com/en/tss-removal-0 http://www.fao.org/docrep/003/T0234E/T0234E01.htm#ch1.2.1
- Lillian
- Lillian And this is the entire SuperPro design, which is basically a more complicated version of the diagram we just saw. In this next portion of our presentation, we will be going into the design of each of these 3 steps. You can see our 3 unit operations: GMF to remove TSS, NF to remove TDS, and chlorination to disinfect. There is also a dechlorination step at the end, which is vital because high concentrations of chlorine are harmful to human and plant health.
- Lillian Moving on to the process section of our project, we had three objectives we wanted to accomplish. These are as follows: remove tss, reduce tds, and disinfect the water. To address each of these objectives, we developed three unit operations: GMF, Nanofiltration, and chlorination. Our justification for each of these unit ops will be explained as we move forward.
- Kylie Goal of our first step is to remove suspended solids; gmf for this. TSS was already so low that we didn’t need to look into more cost effective methods. Ensure maximum function of both steps; poorly designed backwash could result in poor filter operation once flow is resumed The first step in our process is media filtration, the purpose of this is to remove suspended solids. For our design, we chose a dual medium granular media filter consisting of a layer of anthracite, sand, and support layer of gravel, and how this works is the water will pass through the filter and any particulate matter that is too big to pass through the filter will be trapped within the layers. The factors we needed to take into consideration were the medium type, the pore size of the medium, number of layers and depth of each, and filtration rate of the chosen media. Picture1 link: http://wgbis.ces.iisc.ernet.in/energy/water/paper/drinkingwater/simplemethods/filtration.html Picture 2 link: http://napier-reid.com/products/gravity-filtration-systems/
- Kylie Explain function filter Schematic; thicker layer of less dense, anthracite over sand. Water comes in 5.6 MGD = 883262.7 L/h influent→ calculated in order to achieve effluent of 4 mgd More into the actual design and function of the filter. Water will come in through the top and filter through the layer via gravity, exiting at the bottom where it continues to the next step of the reuse process. As time progresses, there will be bwaste build up within the filter layers and at a certain point, this buildup will impact the effectiveness of the system. Once this happens, wastewater inflow to the filter will be shut off and backwashing will occur, which is when high velocity water is forced back up through the filter layers to carry out all the particulate waste and cleaning the filter. In order to prevent bottlenecking and ensure continuous water processing, two gmfs will operated in parallel so one will be cleaned while another is filtering water, and vice versa.
- Kylie will add labels
- Kylie will add labels
- Kylie: Used to design
- Kylie Star means tracked parameters; accomplished first design objective, not treated to title 22 yet, but ones that can be reduced were removed will look into running systems in parallel or having storage basin, weir, so water column above filtration isn’t so high.Realistically, bacteria wouldn’t be 0 after GMF, but it was 0 in SuperPro bc of the huge flow rate of water compared to the tiny flow rate of bacteria.
- Amanda -Now we’ll move on to our 2nd treatment step. -Remember that our second objective is to remove TDS, which includes dissolved salts, metals, and ions. For some perspective...(This is because high salinity can harm plants.) - Membrane filtration reduces TDS. -The semipermeable membrane allows for separation of contaminants and water when the system is pressurized. (the water passes through the membrane and the contaminants are held back, or rejected) - Look at the picture, and you can see our different options for membrane filtration, including MF, UF, NF, and RO. You can see that as pore size decreases, more contaminants are rejected. RO has the smallest pore size and therefore has the highest quality water. RO is often used for potable reuse and is expensive, so our selection for this project is NF. Because it has a high rejection of dissolved solids, but is less expensive than RO. Might use EDR to desalinate ocean water, might use RO to produce potable water. Examples of TDS: calcium, magnesium, potassium, sodium, carbonates, chlorides, fluoride, sulfates)
- Amanda RO rejects 98-99% monovalent ions, NF reject 50-90% depending on material and manufacturer -Now that we’ve selected NF, I’ll go into its structure. -Pore size, mono/di ions (NF pores are small than those of micro/ultra filtration, but larger than those of RO.) -2 configurations (spiral wound has lower pressure drop than hollow-tube and higher surface-to-volume ratio) -The picture shows the flow of water through the filter. Imagine a stack of paper, and roll it up into a spiral. And put that roll into paper towel tube. That’s the structure of NF. The layers of paper are semi-permeable membranes. The clean water flows down the middle of the tube, and the contaminants are trapped in the layers. Picture link: https://emis.vito.be/en/techniekfiche/nanofiltration
- For GMF we could choose our design specifications to fit our requirements. But with NF, the filters are pre-designed by manufacturers, so we researched to find a filter that met our needs. After researching different manufacturers, we found a filter that meets our specifications. come pre-designed to meet common needs for filtration. Amanda 12/4 Note: explain overall water flow through array. Explain 2 blue things are in 1 white thing -Tables: Top one is manufacturer specs for the filter we chose. The bottom table is calculated values -Manufacturer found rejection rate by testing with MgSO4 (magnesium sulfate) -Flux = permeate flow rate over membrane surface area. GFD units are (gal per sq.ft. per day)
- Amanda? -In SuperPro, we want to track the removal of TDS. We’re representing TDS as salinity. In reality, TDS is more than just dissolved salts, but equating the 2 is commonly done in industry. -Our influent TDS is 2000 mg/L. -The table shows SuperPro’s calculations. The TDS concentration went from 2000 mg/L to ~140 mg/L, which meets the requirement of 450 mg/L (according to Water Market Survey). - We also wanted to track nutrient reduction. The ammonia removal is important because in the next treatment step, ammonia reacts with chlorine, and we want to minimize that. -(Tailored SuperPro to fit the needs of the project. (Used microfiltration instead of nanofiltration and increased rejection coefficient to mimic smaller pore size). Mention that removing salinity is important because salts can harm plants. Picture link: http://excelwater.co.uk/systems/nano-filtration-systems/
- Amanda We chose chlorination bc it is commonly used, it is an effective disinfectant, and it has a low cost. -Goal -The disinfection options are… -Look at the table. UV is increasing rapidly but is expensive. Chlorine is common, has a low cost, and chlorine residuals ensure disinfection from plant to consumer. Therefore our selection is chlorine. -Chlorine in general is toxic and corrosive, but chlorine gas and liquid is esp. dangerous. There are many safety regulations on the handling/storage of chlorine gas. For this reason, many plants are switching from gas to sodium hypochlorite, so that is what we chose. Talk about our hesitation we’ve had since choosing chlorine (potentially increasing dissolved solids to the point where it negates the treatment we’ve done) UV requires pretreatment so that the rays can penetrate (disadvantage), but UV takes less contact time (advantage).
- Elena: Sodium Hypochlorite was the chlorine chemical chosen due to its relative ease of handling and its high particle penetration. Chlorine has complex chemical reactions with treated water based on a variety of inputs. ways in which chlorine will be consumed within the contact basin and reduce the available chlorine for disinfection include producing chloramines and THMs from ammonia and nitrate. The ph of the water also influences the equilibrium of hypochlorous acid which is important because hypochlorous acid is much more effective in disinfection than hypochlorite. Based on Title 22, the chlorination step must meet two criteria. a Ct value of 450 which i will explain further and a min retention time of 90 mins. Our literature review showed that a resonable range for residual chlorine is between .2 and 4 mg/L. To model the chlorine in the process this mass balance applies with chlorine in, the amount leaving as redisual and the amount consumed by ammonia. In the field, the chlorine dose often fluctuates based on real time and the exact dose would be normalized using pilot run effluent. Trihalomethanes
- Elena: For our process we decide to design a chlorine contact basin that was rectangular in form since this was one of the most widely used methods. We began this design by calculating the dimensions needed to achieve the minimum retention time of 90 mins (the Title 22 min) with a constant flow rate of 4 MGD. Though we increased the length to produce a total volume of 1250 m squared. This increased in volume increased the retention time to 119 mins. For our process we decide to design a chlorine contact basin that was rectangular in form since this was one of the most widely used methods. The influent to this process was 4 mgd , and we assumed negligible water loss to evaporation. As we developed our specific dimensions, we wanted to insure that we achieved both the minimum retention time required by Title 22 and the needed level of residual chlorine. These structural design parameters (point at em) resulted in a total retention time of 119 mins. Using this parameter and the flow rate of 4 MGD, the dimensions of the contact basin could be calculated and are modeled as shown. At the end of the contact basin will be a wier into the final dechlorination basin. The final effluent shown leaving on the bottom left corner is proper tertiary treated wastewater effluent that eventually can be sent to a water distribution company (CAL water in this case) in order to service San Mateo’s landscaping needs. Measurements in Meters. The depth is 5.00 m in order to have a total volume of 946,250 L and a retention time of 90 mins if the flow rate is 4 MGD. FIX arrows.
- Elena Using chlorine chemistry and the amount of ammonia coming from nanofiltration we calculated the estimated maximum amount of chlorine reacted by ammonia. Then USing the Title 22 CT parameter which is equal to the chlorine residual times the contact time we found the required chlorine residual. IN order to reach equilibrium in our mass balance, we added these values to find the necessary chlorine dose, a total of just under 9 mg.L of NaOCl. This dose after reacting with the ammonia still will leave as a residual and meet the title 22 requirements.
- Lillian: 1-4 mg/l of TSS is what is expected after depth filtration- idk what we want after everything NA: below 50 mg/L; Cl: above 100 for most plants https://extension.psu.edu/interpreting-irrigation-water-tests Note: TDS of 500 mg/L is what plants are typically watered with, and that up to 900 mg/L could be ok, depending on salts present 1.For chlorine disinfection, that criteria is that a contact time of “not less than 450 milligram-minutes per liter... with a modal contact time of at least 90 minutes, based on peak dry weather design flow” is required. In this case, contact time is defined as “the product of total chlorine residual and modal contact time measured at the same point.” 2.applies regardless of the disinfection process: the median concentration of total coliform bacteria in the treated effluent may not exceed “an MPN of 2.2 per 100 milliliters utilizing the bacteriological results of the last seven days for which analyses have been completed.” In addition, # of total coliform bacteria may not exceed “an MPN of 23 per 100 milliliters in more than one sample in any 30 day period,” and no single sample may exceed “an MPN of 240 total coliform bacteria per 100 milliliters” at any time.
- Lillian There are regulations involved, particularly because it is not just salts, there are other contaminants. https://www.usbr.gov/research/dwpr/reportpdfs/report123.pdf
- Elena: In order to address the space constraint we calculated the estimated area needed for each process using our own dimensions and manufacturers specifications. These boxes shown to scale demostrate a possible location to put the process. Nano filtration is our largest process followed by GMF and then chlorination. With communication with the San Mateo Clean Water Program, we found out that this area, though it looks like it is on top of other processes, is actually taken by decommissioned primary clarifiers that have not been in use for years thus is a feasible location for our process. nanofiltration: 4,500 sq ft GMF : 2,600 sq ft Chorination: 2,400 sq ft
- Lillian: 1st bullet, then: A possible distribution system was proposed by the the san mateo water market survey, which was mentioned earlier in the presentation.This was completed by an external engineering consultant for the city of san mateo. They proposed a purple pipeline route based on the potential customers for tertiary recycled water throughout the city. The route the survey proposed would be composed of 6 & 12 in diameter pipes and be a total of $61,600. In 2012, the estimate construction cost to install this new infrastructure was about 15 and a half million dollars. (one other cost thing) (then unit cost). Total Project Capital costs= construction cost + implementation costs + contingency 30% Annualized capital cost is determined with a financing term of 30 years and 3% interest.
- Elena This map (continued on the next slide) is a proposed purple pipeline route designed by an external engineering consultant for the city of san mateo . The red border is the city limits and the blue line is a 6 “ and the black is a 12 “. The green dots are potential recycled water customers who could use the tertiary treated water for landscaping or industrial water cooling towers.
- Elena The line route chose connects the most users in the most efficient path but still do leave out a few other potential users. The larger dots correspond to the potential customers with a higher estimated water demand.
- Elena Like lilian said the estimated cost per AF for the distribution side of the project is $1,530 /AF. Through survey of multiple different californian water reuse projects we found both the cost of the entire project as well as the amount of water they are building for. What resulted was the ability to plot and see the relation that as the amount of water increased, the cost per unit of water decreased. We made this graph to show this relation and used the trendline to estimate the cost of our project based on our size of about 4,500 AF of water treated per year. This resulted in a cost of about $10,500 per AF and when multiplied gives an estimated project cost of just under 50 million dollars. This could be funded by a combination of rates paid by the recycled water consumers and government funding such as that provided by the California Water Recycling Funding Program but further economic analysis will be necessary to ensure its feasibility. https://www.regionalsan.com/sites/main/files/file-attachments/cost-comparison.pdf
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- Amanda This project was in some ways out of our element, and we had a big learning curve. We really enjoyed learning about treatment technologies. We got to network with industry professionals and worked with professors from other departments too. how to apply what we have learned to new areas (Wastewater treatment and water recycling are ever evolving!) (Talking to experts is valuable) (asking the right questions is important) Design is inspired!