The document discusses next generation wastewater treatment approaches at multiple scales from individual buildings to entire watersheds. At the building scale, technologies like greywater treatment and rainwater harvesting are discussed. At the cluster scale, technologies like extracting clean water from wastewater and energy extraction from organics are proposed. Finally, the catchment scale examines resource recovery opportunities at centralized wastewater treatment facilities through incremental process improvements.

1. Next generation wastewater treatment Craig Criddle Civil and Environmental Engineering Stanford University March 31, 2011

4. Wastewater as a Resource Water (99.9%) Biodegradable Organics Nutrients (N and P) Pathogens Salt Refractory Organics Resources Impurities

5. The Value of the Resource Source: Willy Verstraete (2008) Resource Per m 3 US $ per m 3 Organic Soil Conditioner (kg) 0.10 0.03 Methane (m 3 ) 0.14 0.07 Nitrogen (kg) 0.05 0.07 Phosphorus (kg) 0.01 0.01 Water (1 m 3 ) 1.00 0.33

7. Sale price 11 kg methanol $4.50 $0.43/kg catalytic 2 kg fish food $2.00 $1.00/kg biological 5.3 kg methane 1 kg bioplastic $4.70 $4.70/kg biological 0.2 MBTU ~$0.80 $4.10/MBTU thermal

9. Resource recovery can be tailored to local markets and ecosystems requirements.

10. The Stanford-Palo Alto Water Team David Sandy Frank Josh Tom Phil Craig Marty Eun Jung Sebastien Weimin

12. Scale Stanford Campus Catchment of the City of Palo Alto San Francisco Bay Watershed Energy for Transport of Water to User High Low < 200 MJ/m 3 200-1000 MJ/m 3 Stanford Living Innovation Center (Green Dorm)

14. Buildings at Nodes Reuse or Receiving Water Body Treatment Plant Catchment Clusters

15. Building Scale

19. Projected Annual Water Balance % Demand Met by Recycled & Collected Water Outdoor: 100% Greenhouse: 100% Indoor: 48% Overall: 58% 0.01 MG 1.10 MG Indoor Demand 0.62 MG SFPUC 0.74 MG 0.20 MG 0.6 MG 0.10 MG 0.50 MG 0.10 MG Evapotranspiration 0.04 MG Roof Runoff 0.08 MG Evapotranspiration 0.08 MG Rain 0.04MG Leakage 0.07 MG Landscaping Water 0.03 MG Pervious Runoff 0.01 MG Evaporation from Roof 0.05 MG Leakage and Domestic Use Stormwater 0.01 MG 0.03 MG 0.01 MG Sewer Condenser 0.35 MG Blackwater 0.74 MG Greywater

20. Cluster Scale Example: Stanford Campus

21. Water Balance Imported (SFPUC) Wastewater Groundwater Surface Water Stanford University Cluster Units are MGD From Stanford Utilities Losses & domestic use 0.5 0.7 2.3 1.7 Landscape 0.4 Cooling 1.2 0.2 0.01 Potential Resource

22. Water Balance (50% reuse scenario) Imported (SFPUC) Groundwater Surface Water Stanford University Cluster Units are MGD From Stanford Utilities Losses & domestic use 0.5 0.1 1.7 1.7 Landscape 0.4 Cooling 0.6 0.2 0.61 Discharge to sewer decreased by 50%. Can either decrease imported water by 36% OR decrease groundwater use by 86%. % landscape demand met by recycled & collected water = 35%

25. Scalping with Distributed Treatment Sewer Ecosystem Restoration Water Use Aquifer Storage Cooling Washing Clothes Flushing Toilets Agriculture Landscape Salt Removal Process for local recovery or send to sewer Process for local recovery or send to sewer. Nutrient Removal Process residuals for local energy recovery or send to sewer Carbon Removal Advanced Oxidation

26. Scalping Facilities for Water Recovery and Local Reuse Ocean Treatment Plant Scalping Facilities Harvest Water

28. Catchment Scale Example: Palo Alto Catchment Palo Alto Treatment Plant Catchment Scale

29. Palo Alto Catchment Water Balance Los Altos Cluster Mountain View Cluster Imported Water 34 MGD Groundwater 2.9 MGD Surface Water 0.5 MGD Discharge to Bay 24 MGD Palo Alto Cluster Stanford Cluster East Palo Alto Cluster Los Altos Hill Cluster Palo Alto Catchment Wastewater Treatment Plant

30. What Happens with 50% Reuse? Imported Water 24 MGD (29% Decrease) Groundwater 0.3 MGD (90% Decrease) Surface Water 0.5 MGD Discharge to Bay 12 MGD (50% Decrease) Palo Alto Los Altos Mountain View Stanford University East Palo Alto Los Altos Hills Palo Alto Catchment Wastewater Treatment (Concentrated 2X)

31. How Does Resource Value Change at Centralized Facilities If Clusters Reuse 50% & Return Solids to the Sewer? The Value of the Energy and Nutrients Arriving at the Centralized Facility Becomes Equivalent to That of the Water x 2 = $0.36 per m 3 Resource Per m 3 US $ per m 3 Organic Soil Conditioner (kg) 0.10 0.03 Methane (m 3 ) 0.14 0.07 Nitrogen (kg) 0.05 0.07 Phosphorus (kg) 0.01 0.01 Water (1 m 3 ) 1.00 0.33 Resource Per m 3 US $ per m 3 Organic Soil Conditioner (kg) 0.20 0.06 Methane (m 3 ) 0.28 0.14 Nitrogen (kg) 0.10 0.14 Phosphorus (kg) 0.02 0.02 Water (1 m 3 ) 1.00 0.33

32. salt Centralized Facilities for Water, Carbon and Nitrogen Recovery Ocean Treatment Plant Scalping Facilities Harvest Water in Clusters Harvest Water, Energy, Nutrients in Catchment

33. Energy Use at the Palo Alto Treatment Plant (Built in the 1970s) High energy inputs for incinerator! Total = 3,300 MJ/1000 m 3 198 MJ 396 MJ 429 MJ 132 MJ 132 MJ 66 MJ 1914 MJ A Typical Wastewater Treatment Plant Uses 1,200–2,400 MJ/1000 m 3 33 MJ

34. Energy in Sewage 6,000 MJ/1000 m 3 1,000 MJ/1000 m 3 From combustion of reduced carbon (organics) From combustion of reduced nitrogen (ammonia) ~7,000 MJ/1000 m 3 total Recall that a Typical Wastewater Treatment Plant Uses 1,200–2,400 MJ/1000 m 3

35. Flared methane Conventional digesters Egg-shaped digesters in Singapore: designed to improve mixing and ease of solids removal Anaerobic digesters

37. MaxWest Gasifier at Sanford, FL

38. Can we also recover energy from the nitrogen? Nitrous oxide 0.5N 2 O Destroys N 2 O, produces energy, and saves oxygen! 0.5N 2 + 0.25O 2 + 41 kJ Ammonia NH 3 1.0 O 2

39. What new treatment trains might make sense at centralized facilities?

40. Hypothetical Resource Recovery Centralized Process Train Waste water Enhanced primary treatment This process train emphasizes recovery of energy, water for reuse, and inorganic solids production only. Adv Oxid Water for sale O 3 Filter / RO brine ocean O 2 Gasifier Ash H 2 /CO S N 2 Concrete additive or soil amendment CO 2 O 2 Energy for sale Solid Organic Waste Streams Anaerobic treatment CH 4 /CO 2 Energy for sale CO 2 O 2 Dewater solids Low DO N removal P removal O 2 N 2 O N 2 + ½ O 2 Fe (III)

41. But converting existing systems will require baby steps.

42. Existing Plant (Anywhere, USA) Waste water Primary treatment O 2 Thicken solids O 2 Incinerator CH 4 CO 2 Ash Landfill O 2 Trickling filter Activated Sludge Nitrification Filtration UV Ocean

43. Hypothetical Baby Step 1: Enhanced Primary Waste water Enhanced Primary treatment Thicken solids O 2 Incinerator CH 4 CO 2 Ash Landfill O 2 O 2 Trickling filter Activated Sludge Nitrification Filtration UV Ocean

44. Hypothetical Baby Step 2: Digester to Incinerator Waste water Enhanced Primary treatment Thicken solids O 2 Anaerobic digester CH 4 /CO 2 Dewater solids Compost solids To Activated Sludge Nitrification O 2 Incinerator CO 2 Ash Landfill O 2 Trickling filter Activated Sludge Nitrification Filtration UV Ocean Soil amendment

45. Hypothetical Baby Step 3: Digester only Waste water Enhanced Primary treatment O 2 Thicken solids O 2 Anaerobic digester CH 4 /CO 2 CO 2 Energy for sale Dewater solids Compost solids Liquid to Activated Sludge Nitrification O 2 Trickling filter Activated Sludge Nitrification Filtration UV Ocean Soil amendment

46. Hypothetical Baby Step 4: Anammox Waste water Enhanced Primary treatment O 2 Thicken solids O 2 Anaerobic digester CH 4 /CO 2 CO 2 Energy for sale Dewater solids Compost solids Anammox To Activated Sludge Nitrification O 2 N 2 Trickling filter Activated Sludge Nitrification Filtration UV Ocean Soil amendment for sale

47. Hypothetical Baby Step 5: More Anaerobic Treatment Waste water Enhanced Primary treatment Thicken solids Anaerobic digester CH 4 /CO 2 CO 2 Energy for sale Dewater solids Compost solids CH 4 /CO 2 Energy for sale O 2 O 2 Anammox To Activated Sludge Nitrification O 2 N 2 Filtration UV Ocean Soil amendment for sale Anaerobic treatment Activated Sludge Nitrification

48. Hypothetical Baby Step 6: Bio N removal Waste water Enhanced Primary treatment O 2 Thicken solids Anaerobic digester CH 4 /CO 2 CO 2 Energy for sale Dewater solids Compost solids Anammox To Bio N removal N 2 CH 4 /CO 2 Energy for sale O 2 CH 3 OH O 2 N 2 Bio N removal Filtration UV Ocean Soil amendment for sale Anaerobic treatment

50. Hypothetical Baby Step 7: Integrated solid waste Waste water Enhanced Primary treatment O 2 Thicken solids Anaerobic digester CH 4 /CO 2 CO 2 Energy for sale Dewater solids Compost solids N 2 CH 4 /CO 2 Energy for sale O 2 CH 3 OH Solid Organic Waste Streams (food wastes, grease, yard wastes, etc.) Anaerobic digester (hydrolysis) Anammox To Bio N removal O 2 N 2 Bio N removal Filtration UV Ocean Soil amendment for sale Anaerobic treatment

51. Hypothetical Baby Step 8: Methanol production Waste water Enhanced primary treatment Anaerobic digester O 2 brine Thicken solids ocean N 2 O 2 CH 3 OH Solid Organic Waste Streams (food wastes, grease, yard wastes, etc.) CH 4 /CO 2 Dewater solids Anaerobic digester (hydrolysis) Biofuel for sale Anammox To Bio N Compost solids To thickener CH 4 /CO 2 Energy for sale O 2 Bio N removal Water for sale Soil amendment for sale Anaerobic treatment Filtration UV Possible future technology Or might use Anammox here to eliminate methanol requirement

52. Hypothetical Baby Step 9: RO/Advanced oxidation Waste water Enhanced primary treatment Anaerobic digester O 2 O 3 brine Thicken solids ocean N 2 O 2 CH 3 OH Solid Organic Waste Streams (food wastes, grease, yard wastes, etc.) CH 4 /CO 2 Dewater solids Anaerobic digester (hydrolysis) Biofuel for sale Anammox To Bio N Compost solids To thickener CH 4 /CO 2 Energy for sale O 2 Bio N removal Filter / RO Adv Oxid Water for sale Soil amendment for sale Anaerobic treatment

53. Support Woods Institute for the Environment, Stanford University City of Palo Alto Stanford Utilities Cal EPA