Enabling decentralized pre composting of organic household waste with a novel high rate bioreactor. The Urban pre Composter

Transcription

1 Enabling decentralized pre composting of organic household waste with a novel high rate bioreactor The Urban pre Composter M. Sakarika, R. Baetens, K. Vinck, M. Spiller, K.C. Vrancken, G. Van Barel, E. Du Bois, S.E. Vlaeminck

2 Fate of organic household waste in Flanders anaerobic digestion landfilling 6% 2% incineration 24% composting 40% conversion to animal feed 28% [Reference period: 2015] (Roels et al., 2017) 2

3 Cost breakdown composting composting process 26% collection and transport 74% [Reference period: 2009] (Kaza et al., 2016) 3

4 Urban household organic waste composition Household organic waste: vegetables, green, fruit (VGF) Urban household organic waste:mainly kitchen waste Composition of waste disposed in the collection points of the Flanders: meat, fish and poultry 4% bread 15% prepared dishes 6% dairy products (yogurt) 4% sauces, herbs and spices 1% vegetables 35% fruit 35% 4

5 Conventional organic waste flow Collection point Organic household waste High transportation requirements High capacity requirements for centralized composting Mobility problems (traffic) Air pollution Odor Noise 5

6 Novel organic waste flow with the Urban pre Composter Requirements: space limitation compact (high rate) practical allow for loading/unloading minimal use of resources (bulking agents; water) Organic household waste Collection point Reduced transportation requirements Reduced capacity requirements for centralized main composting Decentralized, high rate pre composting Goal: max. mass and volume reduction in 2 weeks 6

7 Challenges in composting kitchen waste Kitchen waste 67 85% moisture 2 lack of structure poor oxygen diffusion addition of structure material high leachate generation 2 (Nair et al. 2006); (Yang et al. 2013) [picture from: 7

8 Research objectives 1. Develop a prototype Urban pre composter and validate achievable mass and volume reduction of kitchen waste 2. Extrapolate to efficiency gains in the overall kitchen waste treatment (pre composting + main composting) 3. Characterize final compost quality 8

9 Reactor design waste load/unload point air outlet pipe nozzle for optional wetting with leachate aerator inlet points motor to rotate agitator static barrel (200L) agitator leachate collection reservoir leachate drainage tube Continuous loading drum bioreactor with forced aeration and internal agitation Capacity: kitchen waste from 44 persons (4.5 L/person) 9

10 Agitator design waste load/unload point motor to rotate agitator static barrel (200L) agitator Design 1: straight scraper with internal void (Runs 1 and 2) Design 2: battlemented scraper with internal bars (Runs 3 and 4) 10

11 Urban pre composter performance % Reductions % reduction batch in 28 days (Yang et al. 2013) Fresh weight Volatile solids (VS) Moisture Volume Run 1 Run 2 Run 3 Run 4 Kitchen waste Formulated Real Sawdust No Yes No Agitator design 11

12 Water balance % Run 1 Run 2 Run 3 Run 4 Evaporation Leachate Waste Minor water removal from leaching Moisture content 56 75% above 55%, so no need for moistening 3 3 (Nair et al., 2006) 12

13 Leachate generation Passive aeration Leachate generation (ml/kgfm) Active aeration Worse case: 400 persons generate 3.5L vs 135L Run 1 Run 2 Run 3 Run 4 Andersen et al., 2011 Amlinger et al., 2008 Low amounts of leachate Can be added to compost (negligible moisture content increase %) no separate collection Upscaling: trade off between energy use (aeration; evaporation) and leachate production 13

14 Research objectives 1. Develop a prototype Urban pre Composter and validate achievable mass and volume reduction of kitchen waste 2. Extrapolate to efficiency gains in the overall kitchen waste treatment (precomposting + main composting) 3. Characterize final compost quality 14

15 Overall treatment: pre composting + main composting % Fed batch, 67 days (Amlinger et al., 2008) 20 0 Fresh weight reduction (%) Volume reduction (%) Time (days) pre composting main composting High rate conversions during pre composting 42% and 71% of overall mass and volume reduction potential achieved in 21% of the time 15

16 Research objectives 1. Develop a prototype Urban pre Composter, and validate achievable mass and volume reduction of kitchen waste 2. Extrapolate to efficiency gains in the overall kitchen waste treatment (pre composting + main composting) 3. Characterize final compost quality 16

17 Compost quality Parameter Unit Produced compost VGF compost composition 4 Requirements for solid organic fertilizers 5 Total solids (TS) %g TS /g product >40 C/N <15 N %g N /g product P %g P /g product K %g K /g product N/P/K 1/0.15/0.08 1/0.11/0.35 1/0.18/0.33 Final moisture removal is needed C/N ratio indicates near mature compost after 68 days Good N/P ratio 4 VLACO; 5 (European Commission, 2016) 17

18 Conclusions 33% mass reduction Collection point Organic household waste Reduced transportation requirements Reduced capacity requirements for centralized main composting Urban pre composting (400 PE: 2.5 m 3 ) Successfully demonstration of the effectiveness and feasibility of urban pre composting at semitechnical scale (200L) No bulking agent addition, no need for separate leachate collection no additional cost for logistics and management 42% and 71% of the overall mass and volume reduction potential achieved in 14 days The urban pre composter lowers overall costs of organic waste management 18

19 Thank you for your attention! Financial support by 19

20 Back up slides 20

21 Neighborhood level waste collection Sorting streets for 400 persons (250 families) 21

22 Composting of real kitchen waste Run 4 40 Mass (kg) Time (days) Mimicking of realistic feeding (fed batch) not full reduction potential (compared to batch process) 22