Three, Not Two! The Case for Separate Organic Waste Management Systems

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1 Three, Not Two! The Case for Separate Organic Waste Management Systems Prof. Harro von Blottnitz (Pr.Eng.) University of Cape Town, Department of Chemical Engineering Environmental & Process Systems Engineering Research Group

2 How strong is this case?

3 Order of argument Background Introduction of dry/wet separation in SA Organic waste review Value proposition Available Technologies Analysis of system change Conclusion

4 Two Stream Waste Separation Dry, clean and recyclable waste receptacle + Original bin for wet waste and everything else destined for municipal landfill. The new materials recovery facilities often incur high capital costs. Recycling was already taking place, driven by informally operating waste pickers

5 What about Organics? Currently, and in new 2-stream systems, the organic fraction is still destined for landfill. The organic fraction contains: Household food / canteen / restaurant waste Garden greens Non-recyclable or non-separated forms of paper Institutional / commercial organics Organic fraction is the main driver of landfill GHG emissions and leachate. In many developed nations landfill disposal of untreated waste no longer allowed.

6 Potential Benefits of Organic Waste Valorisation Value proposition Benefit Recipient of benefit Landfill diversion Extended landfill life Reduced GHG emissions Reduced leachate Municipality rate payer Future generations Neighbouring water users Energy recovery Fuel/energy savings or sales Reduced fossil fuel use AD operator Future generations Reduced fertiliser use Farmer, future generations Nutrient recovery Improved soils Organic certification Farmer Farmer / food consumer

7 A Circular Economy Linear Economy Circular Economy

8 Available Technologies The ABC & worms Anaerobic digestion Bokashi composting Composting Earthworm composting

Anaerobic Digestion Energy recovery solution Produces methane-rich biogas If digestate is contaminated, landfill airspace savings reduced.

9 Anaerobic Digestion Energy recovery solution Produces methane-rich biogas If digestate is contaminated, landfill airspace savings reduced. If digestate is uncontaminated, it can be used as compost or soil improver Size range: from household scale (~ 10m 3 ; > 100 installed*) to industrial/urban scale (~ m 3 ; > 10 installed) Co-digestion is common, especially with sewerage sludge. * Estimated installations in SA, end 2011

10 Anaerobic Digestion UCT Residence

11 Composting Can either be used as a treatment before land-filling, or for nutrient recycling. Often requires significant energy for aeration. Can be carried out at a range of sizes, from backyard composting, to industrial-scale enclosed vessels with oxygen, humidity and temperature control. Composting has been combined with anaerobic digestion in recent municipal schemes.

12 Hot In-Vessel Composting Conventional composting has limitations problem organics including meat, dairy and sewerage. These problem organics are rich in nutrients, but can putrefy easily and harbour pathogens or pests. Hot in-vessel composting operates at roughly 55 C, and have a retention time of about 2 weeks. This sterilizes the composting media no weed seeds, pests or pathogens, and no odours.

Earthworm Composting Earthworms turn and aerate the soil, less machinery. Mostly occurs on a smaller scale than classic composting or anaerobic digestion.

13 Earthworm Composting Earthworms turn and aerate the soil, less machinery. Mostly occurs on a smaller scale than classic composting or anaerobic digestion. Many designs are modular in nature this allows feedstock availability to be matched with processing capacity. Earthworm composting requires pre-sorting (as they do not tolerate all food waste) or pre-composting to stabilize the feed.

14 Earthworm Composting - Hammocks (

15 Combined Composting (

Bokashi-composting (Pickling with Effective Micro-organisms) Mix

sawdust) impregnated with a culture of micro-organisms including:

2 weeks in airtight containers Reduced nuisance and odour Returns

16 Bokashi-composting (Pickling with Effective Micro-organisms) Mix source-separated organic waste with an absorptive substrate (such as sawdust) impregnated with a culture of micro-organisms including: Yeast Lactic Acid Bacteria Phototrophic Bacteria Allow to ferment for 2 weeks in airtight containers Reduced nuisance and odour Returns nutrient value to agricultural land Usually small-scale, stand-alone operations

17 Bokashi in Action Informal Settlement of Enkanini, Stellenbosch Top bucket Bottom bucket Vegetable Garden

18 Part of the value-proposition Community Garden in Kayamandi, Stellenbosch

19 Analysis of system change Thus: at least 4 different treatment routes different combinations of value proposals implementable at different scales Sizeable number of possibilities Confusing? separate collection too costly? Yet, all are in use in South Africa already! What is happening?

20 Traditional waste management responsibility for and the delivery of perspective waste management services are conflated specify, select, command and control approach

21 Systems perspective Modern waste management wrestles with: multiple actors along supply chains of a large variety of goods, differently long use phases; multiple spheres of governance, competing objectives multiple competing pathways for treatment and valorisation as discussed above. Systems tools: many, focus on two here

22 System Drivers Recent internal driver of change in waste management in SA Legislation & regulation External drivers Cost of fuel Value of energy Organic agricultural production Needing organic fertilizers Sustainable development agenda

23 Leverage points Counter-intuitive behaviour of complex systems Levers in the hand of municipal waste managers: Cost of disposal Enforcement of regulations

24 Conclusion: how strong is the case? 4 technical organic waste management solutions already employed by avant-garde Diversity of possibilities appears intractable and costly from the traditional approach Systems approach: Don t wrestle! Let a 1000 flowers bloom? External drivers: energy costs, organic agricultural production Internal leverage: disposal cost and enforcement of regulation

25 Thank you for your attention. Any questions? Prof. H. von Blottnitz (Pr.Eng.) University of Cape Town, Department of Chemical Engineering

Anaerobic Digestion not just biogas production. FARM BIOGAS Methane consulting cc

Anaerobic Digestion not just biogas production FARM BIOGAS Methane consulting cc Use of fire - the greatest achievement of the human race FARM BIOGAS Methane consulting cc Reduction of GHG s emission FARM