Resource recovery in sanitation Mariska Ronteltap
Why sanitation? Chris Buckley Kwazulu Natal: 10 main reasons 1. Public health 2. Public health 3. Public health 4. Public health 5. Public health 6. Public health 7. Public health 8. Public health 9. Public health 10. Public health
Do we still need attention for sanitation? Millennium Development Goals 2008 International Year of Sanitation Prince of Orange figurehead for sanitation Willem Alexander op de bres voor wc's NRC, 21 maart 2008 Kroonprins tegen Afrika: Hef taboe 'poep' op Elsevier, maandag 30 juni 2008 21:29
Do we still need attention for sanitation? Joint Monitoring Program official UN mechanism tasked with monitoring progress MDG 7, Target 7c: "Halve, by 2015, the proportion of people without sustainable access to safe drinking-water and basic sanitation". Publication for 2008 nrs: http://www.wssinfo.org/resources/documents.html
Use of improved facilities 2.6 billion without improved sanitation facilities; 72% in Asia
Sanitation ladder
How can we stimulate connection? By showing the amount of money lost from not having proper sanitation solutions By showing the effect poor sanitation has on the protection of water sources By showing the value of the waste products
Which products in sanitation have value? Wastewater: Black water: yellow + brown (+ flush water) Grey water Storm water Industrial wastewater
Which products in sanitation have value? Nutrients Water (for primary or secondary usage) Energy
Distribution volume and concentrations WATER Volume (L/cap.year) NUTRIENTS COD
Nutrients in urine Nitrogen Phosphorus Potassium Sulphur Calcium Magnesium Micronutrients Oil of the future Threat eutrophication Opportunity complete fertiliser benefit over artificial fertiliser
Driver for phosphorus recovery Phosphorus reserves Economic reasons Available' phosphorus reserves (%) 100 80 60 2% growth 2.5% growth 3% growth 40 20 apatite 0 2000 2010 2020 2030 2040 2050 2060 2070 year Source: Driver et al. (2001)
Nutrient recovery: struvite Requirements: - Presence components - ph 8.5-9 NH 4+ + PO 4 3- + Mg 2+ MgNH 4 PO 4
Urine change during storage Before storage Na opslag urea mg/l 7600 0 ammonium mg/l 480 8000 phosphate mg/l 740 540 magnesium mg/l 100 0 calcium mg/l 180 0 bicarbonate mg/l 0 3200 alkalinity mg/l 22 490 ph - 6.2 9.1 Udert, K.M., Larsen, T.A., Biebow, M, Gujer, W. (2003) Urea hydrolysis and precipitation dynamics in a urine-collecting system. Water Res. 37 (11), 2571-2582.
Urine change during storage Before storage After storage urea mg/l 7600 0 ammonium mg/l 480 8000 phosphate mg/l 740 540 magnesium mg/l 100 0 calcium mg/l 180 0 bicarbonate mg/l 0 3200 alkalinity mg/l 22 490 ph - 6.2 9.1
Struvite precipitation applied full scale Japan, Canada, USA (Ostara) Netherlands: industrial WWT (potato) Nepal: with urine from UDD toilets CrystalGreen TM Several possibilities for SMEs STUN Project, Nepal www.sandec.ch
Other forms of nutrient recovery Phosphorus In the form of calcium phosphate (digester effluent) From ash from incinerated sludge Nitrogen Ion exchange Ammonia stripping and gas washing Drivers Investment cost (reactor volume) Energy: use * price Chemical use Product value!
Example comparison method Maurer, M., Pronk, W., Larsen, T.A. (2006) Water Res. 40, 3151-3166
Other drivers for urine separation? Increase capacity of existing WWTPs Reduction water demand Prevention discharge large part of micropollutants Prevention pathogen mobilisation in onsite systems Wilsenach, J., Loosdrecht, M. (2003) Wat Sci Techn 48(1), 103-110.
Other drivers for urine separation? Increase capacity of existing WWTPs Reduction water demand Prevention discharge large part of micropollutants Prevention pathogen mobilisation in onsite systems Oleja A., Uganda
Faecal matter Mainly interesting for organic matter content After drying: perfect soil improver!
Why drying? 80% volume reduction No water no pathogens Wet mass kg/cap/yr 51 Dry mass kg/cap/yr 11 Total nitrogen kg/cap/yr 0.55 Total phosphorus kg/cap/yr 0.18 Potassium kg/cap/yr 0.4 COD kg/cap/yr 14 BOD kg/cap/yr 7 Values are country-specific or diet-specific (treat as guideline only!) Source: Jönsson et al. (2004), and Otterpohl (2003) for COD BOD assumed to be half of COD
UDD urine diverting dehydrating Maurer, M., Pronk, W., Larsen, T.A. (2006) Review: Treatment processes for source-separated urine. Water Res. 40, 3151-3166.
(Agricultural) value faeces & urine urine none compost improved soil untreated soil Maize (corn) after one week without water Source: GTZ presentations
What you need is what you excrete
Inhibitors reuse in agriculture Social acceptance Institutional issues Availability of arable land Transport issues
Resource recovery without separation Concentrated wastewater: biogas Decentralised systems Recovery at WWTP Reuse of effluent
Kibera Biogas systems Research materials Biogas Training Center (BRC) Chendu, Sichuan, China.
Navsarjan Trust ecosan pilot project proposed system for the DSK Campus dung http://www.alisontoon.co m< source separating toilet greywater (pre-treated) Biogas plant urine storage ornamental garden www.beefgonzo.de biogas sludge drying beds compost vegetable garden
Decentralised systems Europe: more and more sewer-free households A. Peter-Fröhlich et al., Wat Sci&Techn 56(5) 239 249
Also in the Netherlands Sneek: dentralised concept Now 32, soon >200 households Vacuum toilets + kitchen grinders Benefits: Biogas Water saving Recovery
Calculation for 1500 inhabitants Zeeman et al., 2006, Waterforum online
Recovery at WWTP 2 MSc theses 2010: Nanda Sirait: struvite also possible from digester effluent Adriana Inchauste: enhanced orthophosphate after sludge ozonation high potential for P recovery Biogas from sludge digestion Saving possible through optimal process control
Recovery in organic waste + greywater 3d MSc thesis: Annette Nantongo: institutional biogas digesters for organic kitchen waste Greywater: Good fertigation source Aquifer recharge Even up to drinking water quality
Conclusion Recovery possibilities in all sorts of systems Implementation depends on the incentives Countries can learn a lot from each other Sustainable sanitation: wastewater design is a must
Thank you for your attention
Chemical contaminants in urine Heavy metals (Cu, Zn, Cr, Ni, Pb, Cd) Hormones (endocrine disrupters) and pharmaceuticals: Average of 64% of a substance ingested is excreted in the urine (Escher, 2007, p. 24) Better to recycle urine to arable land than to flush into recipient waters because: Hormones and pharmaceuticals are degraded in natural environments with a diverse microbial activity Urine is mixed into the active topsoil and retained for months (see Course 3 Reuse of ecosan products in agriculture )
Benefits of compost for soil fertility (1/2) Compost* improves soil structure: An ideal, friable garden soil consists of airy crumbs in which particles of sand, clay and silt are held together by humic acid. Compost helps these particles to form. Compost increases the water-holding capacity of soil: While 50 kg of silt holds 12 kg of water and 50 kg of clay holds 25 kg of water, 50 kg of compost holds 100 kg of water. A soil rich in compost requires less watering, and plants growing in compost will better withstand drought. Compost moderates soil temperatures: Adding compost to soil tends to keep the soil from heating up or cooling down too rapidly. Soil darkened through the addition of compost absorbs the light and moderates its effect on the growing plant and beneficial soil microorganisms. Compost breaks up organic matter into the basic elements that plants need: Compost is teeming with microorganisms, which continually break down organic matter. * This includes compost made from faeces, faecal sludge and/or organic solid waste (see also Course 2 Unit 6 (Introduction to composting))
Benefits of compost for soil fertility (2/2) Compost returns to soil what agriculture takes out of it: Compost is made up of decaying matter, and it includes nearly every chemical a plant needs, including boron, manganese, iron, copper, and zinc which are not present in commercial fertilisers. Compost releases nutrients at the rate plants need them: Compost acts as a storehouse for nutrients, and slowly releases the nutrients throughout the growing season as the organic material decomposes in the soil. The compost layer prevents the surface from drying out, which increases uptake of nutrients and improves the growth of plants. Compost can neutralise soil toxins and heavy metals: Compost binds metals such as cadmium and lead, making it difficult for plants to absorb them. Compost reduces pests and disease: Compost improves plants' ability to withstand attacks by disease and insects by enhancing naturally occurring microbial agents. Furthermore, it reduces the effects of soilborne pathogens and reduces the amount of plant parasites and nematodes in the soil. Course 3 Unit 2 Source: Esrey et al. (2001), p. 47