Nghiên cứu sản xuất Compost từ rác sinh hoạt

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Rác sinh hoạt- được xem như nguồn tài nguyên vô cùng lớn cần được tận dụng triệt để. Từ rác sinh hoạt, bằng nhiều phương pháp khác nhau người ta có thể sản xuất ra các sản phẩm hữu ích như năng lượng (điện năng, khí sinh học), phân bón,... để phục vụ trở lại nhu cầu con người.

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Nội dung Text: Nghiên cứu sản xuất Compost từ rác sinh hoạt

78 HQi nghj KHOA HQC VA CpNG NGHg 2007 NGHIEN CUtJ SAN XUAT COMPOST TlT RAC SINH HOAT Duong Due Hieu, Vo Thj Hanh, Ngo Ke Sirong Phong Cong nghe biin ddi sinh hoc, Vien Sinh hoc Nhiet dai MdDAU Rac sinh boat - dugc xem nhu ngudn tai nguyen vd cung Idn can dugc tan dung triet de. Tu rac sinh hoat, bang nhieu phuong phap khac nhau ngudi ta cd the san xuat ra cac san pham hiru ich nhu nang lugng (dien nang, khi sinh hgc), phan bdn, v.v... de phuc vu trd lai nhu cau con ngudi [10, 15, 18]. Qua trinh li hieu khi chat thai hiiu co dugc ggi la Composting, cac vi sinh vat cd mat trong ddng li true tiep khoang hoa vat lieu him co tao CO2, khoang chat va chat mun dugc ggi la compost [12]. Do dac tinh ciia rac sinh hoat la phan huy nhanh, cd d^ am cao (>90%), va ty sd C/N thap (14,46-15,29) nen viec tao phan hihi co don thuan tu rac sinh hoat da khdng dem lai hieu qua kinh te ma cdn tao ra d nhiem thii cap nhu nude ri rac va mui hdi [2]. Do do viec phdi trdn giira rac sinh hoat vdi cac nguyen lieu khac nhu mat dira, than bim va bui thudc la de ii se giiip khac phuc dugc nhirng han che vira neu. VAT LIEU VA PHUONG PHAP Nguyen lieu u Nguyen lieu chinh: rac sinh hoat dugc thu gom tir chg nhd (Thu Diic) va chg DT An 2 (Binh Duong). Sau dd, loai bd cac vat lieu khd hoac khdng phan huy nhu nylon, nhua, va vat chat vd co. Phan vat lieu hiru co phan huy dugc la ngudn nguyen lieu lam phan ii. Cac nguyen lieu phu: mat dira (do cac ghe thuyen tai khu vyc Ciu Gd Dua, Q.Thu Dire cung cap), bui thudc la (tir Nha may thudc la Sai Gdn, dudng Trin Phii, Q. 10), than biin (tir cac co sd ban tai Thii Dire). Phuomg phap nghien cuu Md hinh thi nghiem: nhu da de cap d phan md dau, rac sinh hoat cd do im qua cao (>90%), ty le C/N thap (14,95) da han che den viec van hanh composting. Vi vay, d md hinh nay da phdi trdn rac sinh hoat them vdi mdt vai nguyen lieu vira cd kha nane hiit giir am vira cung cap them chat him co nhu than bim, mat dira va bui thudc la. Cac cdng thiic phdi trdn giiia rac sinh hoat va cac nguyen lieu tren nhu sau: Cong thi'cc 1: Rac phdi trdn cd ty le C/N ban dau = 20-22; va do im 75-78% Cong thirc 2: Rac phdi trdn cd ty le C/N ban diu = 30-32; va do im 70-73%. Cong thiirc 3: Rac phdi trdn cd ty le C/N ban dau = 40-43; va do im 58-60%. Ph4n I: CdNG NGHc B|£N Ddi SINH HQC 79 Theo ddi va phan tich cac chi tieu: nhiet dg, do im, pH, cac bon him co, nito nhdt pho (dang P2O5), kali (dang K2O), axit humic, tdng vi sinh vat hilu khi, vi sirih vat'nhSn giai cellulose. Trong thi nghiem nay, nhiet do dugc theo doi moi ngay, cdn cac thdng sd do im pH va C/N dugc xac dinh moi tuan. Kit qua dugc phan tich biln lugng va xlp hang bing trac nghiem Duncan cho thiy, vdi mire y nghia 0,000 (- ^ C 6 n g t h J c l =M -^Wngthilc 1 § 30 ^ •r 5 ^ *" Cdng Ihiici >S 25 - ••».^ -* C6nglhiJc2 a 1 - - Cii ng IhiJc 3 P 20 - ' ' » Cong IhJc 3 " 3- 15 - 2 •• 10 - 1- 5- 0 7 14 21 28 35 0 7 14 21 28 35 2a ThffI gtan (ngiy) 2b Thtri gian (nm) D6 thj 2. Sy thay d6i pH v^ ty s6 C/N theo thiy\ gian cua ddng u composting rac phdi trgn Dd thi 2a cho thay dien bien ciia pH trong sudt qua trinh ii d ca 3 cdng thuc diu nam trong khoang trung tinh (pU = 7 - 8 ) . Gia tri pH nay khdng nhimg da han chi viec that thoat nito ma cdn thich hgp de vi sinh vat oxy hoa cac hgp chit hiru co. pH ban diu khdng anh hudng nhieu den viec van hanh composting cho du cao hay thip. Nhilu tac gia da khao sat [6, 11] va cho biet pH ban dau dao ddng frong khoang 5 - 9 van cd thi ii compost cd hieu qua. Ty le C/N la thdng sd quan trgng cua qua trinh ii rac sinh hoat. Kit qua dd thi 2b cho thay, trong 2 tuan dau C/N cua cac cdng thirc deu giam rd ret, do rac cho tuoi da kich thich hoat ddng oxy hoa cac hgp chat hiru co bdi vi sinh vat dien ra nhanh hon cang ve sau co chat da dan dn dinh, hoat ddng cua vi sinh vat cham lai. C5 cdng thiic 2 hieu qua xir ly rac phdi trdn cao hon han so vdi cdng thirc 3 va 1, hon nira ty sd C/N sau ciing bang 12, nam trong gidi han cho phep cua tieu chuin phan bdn quy dinh trong khoang 10-15 [16]. Cd le d cdng thirc 3 ty le C/N cao (>43), va cd do am ban dau tuong ddi thap (22,5); ngugc lai, d cdng thiic 1 ty sd C/N ban diu hoi thip (75%) khdng chi lam cho mdi trudng cua khdi ii trd neii yem khi ma nhiet do cdn bi giam xudng rd ret tir nhiing ngay diu ciia friin thii 2. Ty le C/N tdi uu cho qua trinh ii composting dao ddng tu 25-35 [7, 13]. 3. San pham phan huu co" sau 35 ngay u compost BSng 3. D?c tinh hoa ly va sinh hgc cua phan hu-u ca sau 5 tuin u Chi tieu Cac cong thiJC r i c ph6i trpn Cong thiPC 1 Cong thi>c 2 Cong thirc 3 pH 7,68 7,55 7,20 DO km {%) 63 49 40 Cac bon hO-u ca (%) 21,28 21,10 20,00 T6ng nito' (%) 1,54 1,63 1,64 Ph6tpho dgng P2O5 {%) 0,33 0,36 0,47 Kali dgng K2O (%) 1,17 1,24 1,28 Axit humic (%) 7,05 7,75 7,54 Cellulose (%) 25,65 25,43 25,25 Ty 1$ C/N 13,81 12,04 22,50 0^ din (Ji$n (mS/cm) 12,07 12,76 12,99 Vi khu4n (CFU/g): - T6ng vi khucin 4,1x10' 4,1x10' 4.3x10' - VK phSn giSi cellulose 2.4x10' 2,3x10' 3,1x10' Vi nim (CFU/g); - T6ng vi nim 5,8x10' 5,9x10' 5,8x10' - VN phSn giSi cellulose 2,5x10' 2,2x10' 3,1x10' Xg khuin (CFU/g): - T6ng xg khuin 4,6x10' 4,5x10' 4,9x10' -XKphdn gidii cellulose 8,6x10^ 8,4x10' 1,3x10' Ket qua ghi nhan frong bang 3 cho thiy compost dugc lam tir hon hgp rac sinh hoat vdi mat dira, than biin va bui thudc la nhin chung dat tieu chuan phan bdn quy dinh. Tdng VSV hilu khi va VSV phan giai cellulose ciia ca 3 cdng thirc deu cao (106-107 CFU/g); ham lugng axit humic d thi nghiem nay dao ddng tir 7-8%, cao hon rit nhieu so vdi compost don thuin dugc lam tir rac chg (3,7-3,8%) [2]; do dan dien (EC) cao hon 2 lan so vdi do dan dien cua phan him co che bien tir rac sinh hoat. Cd le qua trinh tao miin dien ra phiic tap, d giai doan diu vi sinh vat khoang hoa chat hihi co de phan huy, giai doan 2 tao chit mim vdi thanh phan chii yeu la: axit humic, fulvic, humin,v.v..., nhung chu ylu la axit humic [9]. C> giai doan nay phan huy nhu lignin, hemi-cellulose va cellulose thanh chit miin chi nhd hoat ddng ciia vi sinh vat d dieu kien yi hieu khi. Chinh vi vay nhiing loai phan hiiu co dugc lam tir ngudn thai giau hgp chat khd phan huy thudng cd ham lugng axit humic nhieu hon (phu thudc vao thdi gian va phuomg phap ii). Do dan dien EC la thdng so ndi len sy hien dien ciia cac ion Na"", Ca"^, Mg"^, 82 HQi nghj KHOA HQC VA C(^NG NGHE 2007 K"", Cr, SO4'', NO3', C03^' d dang mudi hoa tan frong phan u him co [14]; miu phan ii hihi CO lam tir rac phdi frdn cd thanh phan dinh duong d dang hoa tan cao hon nhieu so vdi mau phan hiru CO don thuan tir rac sinh hoat. , -,_ • .HA KET LUAN ' • •'^'J';l Viec phdi trdn rac sinh hoat vdi cac nguyen lieu (mat dira, than bim va bui thudc la) khac da giiip qua trinh ii compost hieu qua hon, khdng tao ra d nhiem thii cap (nude ri rac va miii hdi bdc len tir ddng u). Trong thi nghiem nay, cdng thuc 2 la cdng thirc phdi frdn tdi uu nhat cho qua frinh ii compost. Gia tri tdi uu cho qua trinh u compost la: can duy tri khoang nhiet do thermophilic (> 50°C) tir 1 den 2 tuin, do am ban dau 70%, ty le C/Nban dau la 32. Phan ii him co thu dugc cd ham lugng axit humic 7-8%, ty sd C/N sau ciing la 12, tdng vi sinh vat hieu khi va vi sinh vat phan giai cellulose nam frong khoang 106-107 CFU/g. " ^' "• TAI LIEU THAM KHAO 1. Nguyen Lan Diing va cac tac gia (1979). Mdt sd phuong phap nghien cuu vi sinh vat, tap 2, NXB Khoa hgc va Ky thuat. Ha Ndi. • " 2. Duong Diic Hilu (2005). Nghien cuu iing dung mdt sd chi phim vi sinh de xu ly rac sinh hoat thanh compost, Luan van thac sy khoa hoc mdi trudng, Trudng Dai hgc KHTN, TP. HCM 3. Bari Q. H. and Koenig A. (2001). Effect of air recirculation and reuse on composting of organic solid waste. Resources, Conservation and Recycling 33 p 93-111. ' ' 4. Beffa T. et al. (1996). Isolation of thermus sfrains from hot compost (60 to 80°C). Appl. Environ. Microbiol, 62, p. 1723-1727. 5. Brinton W. F. (2000). Compost quality standards & guidelines. New York State Association of Recyclers. Woods end Research Laboratory. 6. Komer et al. (2003). hivestigation and optimization of composting processes test systems and practical examples. Waste Management, 23, p. 16-26. 7. Kuhlman L. R (1990). Windrow composting of agricultural and municipal wastes. Resources, Conservation and Recyclmg, 4, p. 151-160. 8. Martin Tanner (2003). Nifrogen in co-compost and other chemical compost analyses. Report of a field in Kumasi, Ghana, SANDEC. 9. Marja Tuomela (2002). Degradation of lignin and other '^C-labelled compounds in compost and soil an emphasis white-rot fungi. Academic dissertation in microbiology. University of Helsinki. 10. Mbuligwe S. E. et al. (2002). Potential and confraints of composting domestic solid waste in developing countries: findings from a pilot shidy in Dar es Salaam Tanzania. Resources, Conservation and Recycling, 36, p. 45-59. ' Phin I: CdNG NGHg B | £ N Ddi SINH HQC 83 11. Nakasaki K. et al. (1993). Effects of pH control on composting garbage. Wastes Management Resousces, 11, p. 117-125. 12. National Engineering Handbook (2000). Composting. Natural Resources Conservation Service, United States Department of Agriculture. 13. Sadaka S. and A. El. Taweel A.El. (2003). Effects of aeration and C:N ratio on household waste composting in Egypt. Compost Science & Utilization, vol. 11, No. 1, p. 3640. 14. Subjaream et al. (2002). The efficiency of some microbiol activators in organic composting from market wastes. Symposium, 57, paper no. 2315. 15. Tchobaglous G. et al. (1993). Integrated solid waste management. McGraw-Hill, New York. 16. Tom L. R. et al. (2002). Moisture relationships in composting processes. Compost Science & Utilization, vol. 10, No. 3, p. 286-302. 17. Wayne H. T. (2001). Test methods for the examination of composting and compost. 18. Wei et al. (2003). The technology of the municipal solid wastes composting. Namre and Science, 1(1), China, p. 91-94. 0 SUMIMARY Study on production of compost from municipal solid wastes jv t Duong Due Hieu, Vo Thi Hanh, Ngo Ke Suong v/' • Institute of Tropical Biology h Composting has become increasingly popular in the past decade as a biological freafrnent process of municipal solid wastes, with the purpose of recovery, stabilization and volume reduction of waste material in the form of compost. In this study, the effect of coconut coir dust, peat and tobacco residues addition on municipal solid wastes composting process was investigated. The first, second and third fomulas adjusted average intilial C/N rafro and moismre was 20 and 75%, 30 and 70%, 40 and 60%, respectively. The results show that (i) the municipal solid wastes mixed with coconut coir dust, peat and tobacco residues was composting better than confrol (without mixture); (ii) during composting, secondary pollution (such as leachate and odour) was not released; (iii) the second formula is the best for the composting process because of the maintained thermophilic phase (>500C) from one to two weeks, 70% initial moishire, 32 C/Ninitial ratio; and (iv) final compost contained 8% humic acid, C/Nfinal ratio is about 12, the amount of total aerobic and cellulose decomposing microorganisms are about 106-107 CFU/gr.