Addressing health concerns of waste reuse

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Addressing health concerns of waste reuse Addressing health concerns of waste reuse Presentation Transcript

  • www.iwmi.org Water for a food-secure world Addressing health concerns of waste reuse Philip Amoah (PhD)
  • www.iwmi.org Water for a food-secure world Outline  Background  Health issues in  faecal sludge composting  wastewater irrigation  aquaculture Risk reductions strategies
  • www.iwmi.org Water for a food-secure world Fecal sludge management  In most cities in Africa, population growth outpaced the development of sanitation infrastructure  the management of urban waste (solid and liquid) ineffective. Background
  • www.iwmi.org Water for a food-secure world  Sewer networks in SSA are collecting only a small percentage of wastewater generated.  The few wastewater treatment plants are usually not functional or overloaded.
  • www.iwmi.org Water for a food-secure world Current methods of waste reuse
  • www.iwmi.org Water for a food-secure world Waste is a potential vehicle for pathogens in the food chain  Bacteria : Salmonella spp. , E. coli etc…  Viruses: Norovirus etc  Protozoa: Cryptosporidium, Cyclospora, Giardia,  Helminths: Fasciola spp., Taenia spp, Ascaris Lumbricoides
  • www.iwmi.org Water for a food-secure world Who is at risk? Consumers Farmers and their families
  • www.iwmi.org Water for a food-secure world Benefits of waste reuse
  • www.iwmi.org Water for a food-secure world I J K L Feedstock E. coli (cfu/10g Dry wt) F. coliform (cfu/10g Dry wt) Raw FS 4.2 x 106 ± 2.9 x 103 5.0 x 107 ± 2.6 x 105 Feedstock E. coli (cfu/10g Dry wt) F. coliform (cfu/10g Dry wt) Dry FS 6.0x104 ±1.6 x103 5.9 x104 ± 7.0 x 102 Microbial populations in raw and dry faecal sludge
  • www.iwmi.org Water for a food-secure world Day 1 after composting I J K L Turning compost (weekly) Matured compost after 90 days Heat generated during composting kills pathogens Compost temperature taking
  • www.iwmi.org Water for a food-secure world I J K L 0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 1 5 9 13 17 21 25 29 33 37 41 45 49 53 57 61 65 69 73 77 81 85 89 93 97 Temperature(dgreescelcius) Temperature changes during the composting process. Days
  • www.iwmi.org Water for a food-secure world A= FS + EFB; 1:1, B= FS + CPH; 1:1, C= FS+EFB+CPH; 1:1:1, D= FS+EFB+CPH; 2:1:1, E= FS+EFB+CPH; 2:2:1. Changes in E. coli populations in compost piles during composting. 0.00 1.00 2.00 3.00 4.00 5.00 6.00 0 3 6 9 12 Escherichiacoliinlogunits Weeks after composting A B C D E FS = Faecal sludge; EFB= Empty fruit bunches; CPH= Cocoa pod husk
  • www.iwmi.org Water for a food-secure world I J K L Wastewater generation Consumer Wastewater treatment Safe produce … Multiple barrier approach from “Farm to Fork” Wastewater generation Farmer/ Producer Traders/ Retailers Street food kitchens Consumer Wastewater treatment Safe Irrigation Practices Hygienic Handling Practices Safe food washing and preparation Awareness creation to create demand for safe produce Policy recognition, safer farm land, tenure security, market incentives, safe-food labelling,… Wastewater Irrigation
  • www.iwmi.org Water for a food-secure world Safer irrigation practices • Drip irrigation • Furrow irrigation • Avoiding soil splash • Cessation of irrigation • Avoid stirring up sediments Farm level reduction by 2 - 4 log units
  • www.iwmi.org Water for a food-secure world Ponds trials – Sedimentation
  • www.iwmi.org Water for a food-secure world 0 2 4 6 8 10 12 Karikari Gyenyase Helmintheggs(No.ofeggs/l) Settled Unsettled Sediments Indicator Organisms in ponds under different conditions
  • www.iwmi.org Water for a food-secure world Improved use of watering cans >1m, Uncapped >1 m, Capped 0.5-1.0m, Capped Irrigation height (m) Thermotolerant coliforms (log MPN 100 g-1) Capped Uncapped Helminth eggs (No.100 g-1) Capped Uncapped Dry season Wet season < 0.5 0.5 - 1.0 > 1.0 < 0.5 0.5 - 1.0 > 1.0 4.7 ± 0.1 5.4 ± 0.4 5.9 ± 0.4 6.5 ± 0.1 6.6 ± 0.1 7.7 ± 0.1 5.4 ± 0.3 5.7 ± 0.4 7.8 ± 0.4 7.5 ± 0.1 7.7 ± 0.2 8.47 ± 0.1 0.3 ± 0.2 1.0 ± 0.3 1.6 ± 0.3 0.7 ± 0.3 1.5 ± 0.4 1.4 ± 0.3 1.1 ± 0.4 1.6 ± 0.3 2.6 ± 0.4 1.4 ± 0.5 2.0 ± 0.4 2.9 ± 0.4 (n= 30 lettuce samples per height per season)
  • www.iwmi.org Water for a food-secure world Improving common salad washing practices in homes and street food kitchens  Common practices: 6 - 36% bacteria reduction  Improved practices: 50-100% bacteria reduction Challenges: Availability & price of e.g. chlorine tablets
  • Photo:DavidBrazier/IWMIPhoto:TomvanCakenberghe/IWMIPhoto:DavidBrazier/IWMIPhoto:DavidBrazier/IWMI Method Use Contact time Mean log10 FC levels before and after treatment Log reduction Before After Running tap I I 3-4 sec. 2 min. 5.5 6.1 5.2 3.9 0.3 2.2 NaCl7 NaCl23 NaCl35 NaCl7 NaCl23 NaCl35 I I I I I I 3 – 4 sec. 2 min. 5.5 5.5 5.5 6.1 6.1 6.1 5.0 4.7 4.4 4.7 4.6 4.0 0.5 0.8 1.1 1.4 1.5 2.1 NaCl7 + Vin6818 I 3-4 sec. 2 min. 5.5 6.1 5.2 4.7 0.3 1.4 Vinegar6818 Vinegar12500 Vinegar21400 I C C 3-4 sec. 2 min. 5 min. 10 min. 5 min. 10 min 5.5 6.1 3.7 3.7 4.7 4.7 5.3 5.1 1.9 0.0 0.0 0.0 0.2 1.0 1.8 3.6 4.7 4.7 Efficacy of common methods at different exposure times (N= 10 for each treatment)
  • Mean log10 FC levels Method Use Contact time Before After Log reduction Removal of outer leaves (Vinegar 12500) C C 5 min. 10 min. 4.3 4.3 3.8 3.4 0.5 0.9 Laundry Omo™ (Detergent) C C 5 min 10 min 4.3 4.3 1.7 1.9 2.6 2.4 Eau de javel™ (I65μS/cm) Thick Bleach™ (248μS/cm) Power Zone™ (223μS/cm) I C C C C C 5 min 10 min 5 min 10 min 5 min 10 min 6.4 6.4 6.3 6.3 6.3 6.3 4.0 3.5 3.8 3.8 4.1 3.3 2.4 2.9 2.5 2.5 2.2 3.0 KM100 KM200 I C 3-4 sec 2 min 5 min 10 min 5.5 6.1 6.4 6.4 4.8 4.9 4.4 3.9 0.7 0.6 1.0 2.5 CL tabs100 C C 5 min 10 min 6.4 6.4 4.1 3.7 2.3 2.7 Efficacy of common methods Continued
  • www.iwmi.org Water for a food-secure world 0 2 4 6 8 10 12 14 1 2 3 4 5 6 7 8 Washing methods Numberofhelmintheggs100g-1wet weight 1) Unwashed, 2) Light washing in a bowl, 3) Washing in salt solution(7 ppm) 4) Washing in salt solution (23 ppm), 5) Washing in salt solution (35 ppm) 6) Washing under running water, 7) Vinegar solution 6818 ppm 7) Salt/vinegar solution (7 ppm/6818 ppm) Efficacy of common washing method on helminth egg contamination
  • www.iwmi.org Water for a food-secure world I J K L Wastewater treatment plant (e.g. WSP, anaerobic/aerobic reactors ) $ $ consumers $ aquaculture farmers/labor, inputs Aquaculture
  • www.iwmi.org Water for a food-secure world Stabilization ponds (maturation) in Kumasi
  • www.iwmi.org Water for a food-secure world Microbiological quality of C. gariepinus (CFU/g) raised in WFP and NWFP Fish tissue Pathogen NWFP WFP Skin Total coliform 1.3 x 104 6.8 x 105 E. coli 2.1 x 103 4.2 x 105 Salmonella spp ND ND Helminth eggs ND ND Flesh Total coliform 3.7 x 102 4.2 x 102 E. coli ND ND Salmonella spp ND ND Helminth eggs ND ND Gut Total coliform 2.0 x 102 1.2 x 103 E. coli 1.4 x 102 3.6 x 103 Salmonella spp ND ND Helminth eggs ND ND
  • www.iwmi.org Water for a food-secure world Heavy metals concentration (mg/l) in pond water Heavy Metal Concentration (mg/l) Guidelines NWFP WFP WHO FAO Fe 1.37±0.22 2.05± 0.07 0.30 5.00 Cu 0.04±0.01 0.05± 0.02 2.25 0.20 Zn 0.27±0.04 0.39± 0.21 5.00 2.00 Mn 0.03±0.01 0.05± 0.01 0.50 0.20 Pb 0.05±0.01 0.06± 0.01 0.05 5.00 Cd 0.02±0.00 0.03± 0.01 0.01 0.01  Apart from iron heavy metals in gills, muscle and liver were below permissible levels
  • www.iwmi.org Water for a food-secure world Emerging contaminants S. Asem-Hiablie et al., (2013) Serum estrogenicity and biological responses in African catfish raised in wastewater ponds in Ghana . Science of the total environment Biological effects of reusing water in aquaculture tested  Similar body indices in catfish from both freshwater and treated municipal wastewater  Suggests that municipal wastewater may be amenable for use in aquaculture in some cases.
  • www.iwmi.org Water for a food-secure world Thank you Email: p.amoah@cgiar.org