China Agricultural University (CAU) jingyuan@cau.edu.cn Naxos, June - PowerPoint PPT Presentation

Effects of the aeration pattern, aeration rate and turning frequency on municipal solid waste biodrying performance Jing Yuan China Agricultural University (CAU) jingyuan@cau.edu.cn Naxos, June 13, 2018

Outline  Background  Objectives  Materials and Methods  Results and Discussion  Conclusions

Background 240 100 MSW collection MSW collection (millon t /a) Rate of harmless disposal (%) 203,6 kitchen waste Rate of harmless disposal 80 180 plastics 0 % 2 % 2 % 0 % 3 % 3 % paper 60 1 2 % fabric 120 woody waste 40 1 3 % glass 6 5 % rubber 60 20 metal Ash 0 0 The amount of municipal solid waste (MSW) produced in China and the rate of harmless disposal (%)  High proportion of kitchen waste Organic matter 70~80% Huge potential energy sources Water content 70~80%  High proportion of high heat value substance Plastic, paper, fabric and woody waste ＞ 30% The HHV of MSW increase.

Disposal way of MSW and biodrying technology 1000 Biodrying , a pretreatment method Landfill Composting targeting incineration, which aims at Disposal plant of MSW 800 Incineration removing water from bio-wastes with high others 600 water content (Zhang et al., 2009). Besides having a high water-removal rate, 400 this approach is expected to constrain organic degradation, thereby preserving Combustion 200 energy for subsequent utilization, e.g., as residue-derived fuels (RDF) (Velis etal., 0 2009). W ater recovery  The main factors restricting the recycling of MSW High m oisture Heat 4 cycle

Effect of aeration rate on biodrying High aeration rate Low aeration rate Lower water carry capacity Lower matrix temperatures less evaporated water will be Less evaporated water removed aeration Temperature Balance Optimum aeration pattern and rate

The main objective To study the interactive influences of the aeration pattern, aeration rate, and turning frequency on biodrying performance of municipal solid waste (MSW). Water-removal rate  Biodrying index  Mass balance  Heat balance 

Materials Mixes of MSW Materials MSW Cornstalks MSW 9 0 % and cornstalks Moisture (%) a 71.47 4.67 60.39 694.97 168.14 513.13 Bulk density (kg·m − 3 ) a 30.85 84.23 51.01 Free air space (FAS) (%) b Total carbon (TC) (%) b 35.97 42.72 39.48 Total nitrogen (TN) (%) b 1.82 1.11 1.47 Cornstalks 1 0 % C/N 19.76 38.49 26.86 Volatile solids (VS) (%) b 72.64 89.3 80.91 Lower heat value (LHV) -366 14664 2422 (kJ·kg − 1 ) a 7

Refrigerator 8 Biodrying vessel （ 60L ） condensate 50 mm C-LGX Condensate collection

Design of the experiment Aeration rate Total aeration Turning Treatment Aeration method (L kg − 1 volume frequency DMmin − 1 ) (m 3 ) a Intermittent (Aerate 10 min and I1 stop 20 min during Days 0–6) + 0.35 (average 0.3) 3 days 90 Continuous (Days 5–18) Intermittent (Aerate 30min, stop I2 0.6 (average 0.3) 3 days 98 30 min) C1 Continuous 0.2 3 days 55 C2 Continuous 0.3 3 days 91 C3 Continuous 0.4 3 days 128 C4 Continuous 0.5 3 days 163 C5 Continuous 0.6 3 days 195 T0 Continuous 0.3 Non 90 T2 Continuous 0.3 2 days 93 T6 Continuous 0.6 6 days 198 9 Actual total aeration volume during the biodrying process.

Results and discussion  Temperature 100 100 100 C2 I1 T0 T2 C1 C2 C3 C4 I2 C5 C2 T6 C5 ambient ambient ambient 80 Temperature ( � ) 80 80 60 60 60 40 40 40 20 20 20 0 0 0 0 3 6 9 12 15 18 0 3 6 9 12 15 18 0 3 6 9 12 15 18 Time (days) Time (days) Time (days) Treatment I1 I2 C1 C2 C3 C4 C5 T0 T2 T6 TI ( � ) 756 733 737 759 695 681 701 761 688 644 TI: the temperature integration index  No significant differences were found between the 10 treatments overall.  The temperature was affected little by increasing the aeration rate above that required to satisfy the oxygen demand of the microorganisms.

 Water-removal rate during biodrying 2,0 2,0 2,0 Water removal rate (kg d -1 ) T0 C1 C2 T2 C2 I1 1,5 1,5 1,5 C3 C2 I2 C4 T6 C5 C5 1,0 1,0 1,0 0,5 0,5 0,5 0,0 0,0 0,0 0 3 6 9 12 15 18 0 3 6 9 12 15 18 0 3 6 9 12 15 18 Time (days) Time (days) Time (days)  In all the treatments, water loss mainly occurred in the thermophilic phase (days 7~12), accounting for 50%~68%.  Air volume and water evaporation significantly positively correlated between days 1~9.  Water loss mainly depended on the total aeration volume , different aeration patterns and turning frequency affecting water loss little at a constant total aeration volume.  C4 ( 0.5 L·kg − 1 DM·min − 1 ) is the optimum aeration rate, biodrying performance decreasing at aeration rates higher than the optimum.

 Water and volatile solid (VS) losses Treatments Water removal rate VS loss rate Biodrying index Heat utilization (%) (%) （ I ） rate （ % ） I1 51.53 39.02 2.86 50.6 I2 49.74 39.69 2.72 52.0 C1 31.23 36.51 1.7 42.3 C2 48.87 40.39 2.45 53.3 C3 56.76 38.8 3.17 59.8 C4 66.01 34.72 4.12 68.3 C5 62.39 34.47 3.81 65.8 T0 41.91 35.31 2.32 43.8 T2 49.87 41.45 2.49 51.2 T6 59.44 35.38 3.63 60.1 Biodrying index （ I ） = water loss /VS loss Heat utilization rate （ % ） = The heat used by evaporation/Generated heat by VS degradation

 Characteristics of the final biodrying product Treatments I1 I2 C1 C2 C3 C4 C5 T0 T2 T6 Moisture (%) a 33.25 45.8 46.2 54.04 47.47 41.35 37.33 51.89 45.34 42.43 Bulk density 290.89 369.5 359.2 470.35 396.32 320.94 315.76 482.94 316.29 328.13 (kg·m − 3 ) a FAS (%) b 74.81 67.10 68.3 57.63 64.82 71.84 72.29 57.12 71.86 70.92 TC (%) b 31.99 33.5 32.2 31.33 30.64 31.04 31.33 31.49 32.6 33.01 TN (%) b 1.93 1.9 1.9 1.74 1.86 2.07 2.08 1.96 1.93 1.94 C/N 16.58 18.0 17.0 18.01 16.47 15.00 14.58 16.07 16.89 17.02 VS (%) b 66.57 66.2 63.3 64.08 63.48 65.17 67.40 66.19 61.40 67.1 LHV (kJ·kg − 1 ) a 9440 4435 4569 3717 4499 7177 8678 3165 4348 5333 The initial moisture content was 60.39%, treatment C4 gave the lowest final moisture content (33.25%) and the highest LHVs 9440 kJ kg -1 .

Conclusions  Biodrying performance was most affected by aeration volume.  Biodrying performance decreased above the optimum aeration rate.  An aeration rate of 0.5 L·kg − 1 dry matter min − 1 and one turn each 3 d were optimum.  The optimum results were 66% water removal and 68.3% of heat used for evaporation.

Acknowledgment The National Key Research and Development Program of China (No.2017YFNC060039). Thanks for your attention! Questions?