October 26, 2010 | General

Global Roundup

BioCycle October 2010, Vol. 51, No. 10, p. 27

Cairo, Egypt, biosolids compostingMakati City, Philippines
Growing pineapples is a multiyear process, with harvest typically occurring the third year after planting. Growers may get in several harvests at that point, the first being the best. “That crop is normally sold as fresh pineapple,” explains Stan Brown of Brown Bear Corporation. “They may get one or two more harvests the same year but the pineapples are smaller and those usually go to a cannery. Once the final harvest has been made, the growers get ready to replant. In years past, they would burn the fields to get rid of the biomass because it made plowing the fields very difficult. This left the soils completely depleted of any organic matter.” Growers recognized they had to incorporate the biomass. They sprayed it with paraquat (agent orange) to defoliate, then pulled huge disc plows over the field. “Sometimes they spent up to a year working the biomass into the soil before they could deep plow and replant,” says Brown.
Brown Bear developed the Green Mulcher by modifying its brush cutting machines to shred and incorporate the pineapple biomass into the soil. “Growers don’t need the paraquat and could deep plow immediately following the mulcher, thereby cutting the layout time from one year or sometimes 18 months down to about two weeks,” he adds. Dole Philippines, located in southern Mindanao at Makati City, purchased several Green Mulchers (5000 series). The 350 HP custom-designed units have a front-mounted flail cutter and counter-rotating rotor. The heavy free swinging heat-treated flail knives lift the pineapple leaves and stems, mulching them before the tires run over the plants.
Cairo, Egypt
A composting project in Cairo has the goal of processing one million tons/year of biosolids using rice straw and “recycle cake” to dry down the material and provide pore space. Resource Recovery Systems International (RRSI) is a consultant to the project. “Many years ago, sludge with a very high moisture content was delivered to large ditches dug in the desert,” says Les Kuhlman of RRSI. “Because of the sandy soil, the liquid portion soaked away quickly. This system was discontinued 12 years ago.” Currently, biosolids are pumped to a drying bed covering about 800 acres. Drying occurs slowly, reaching about 75 percent moisture. “The drying bed is full now,” adds Kuhlman. “When composting a million tons of biosolids annually, one bay would be emptied and refilled every day.”
A small composting project is operating at the site. Biosolids are removed from the drying beds, mixed with shredded rice straw and composted in open windrows for six to eight weeks. After the windrow phase, the compost is placed in curing piles, screened and bagged. Compost is sold for use in the production of numerous agricultural crops. A small amount of dried biosolids is also sold to farmers, a practice likely to be discontinued. Kuhlman explains that the common practice in Egypt is to burn rice straw, which causes considerable air pollution during the season of rice straw burning. “This will likely lead to a ban on this practice,” he says. “Incorporating rice straw in the composting process is seen as an excellent way to utilize large amounts of straw and reduce air pollution.”
RRSI is also involved in the manufacture of windrow turners in Egypt. It supplies component parts to an Egyptian company that builds the frame and assembles the turners. Thus far, the partnership has completed 20 turners used for composting MSW throughout Egypt.
Benet, France, food waste digester
Benet, France
An anaerobic digester facility owned and operated by Bionerval-SIFFDA in Benet is designed to process 40,000 metric tons/year of industrial and commercial food waste. Construction of the plant got under way in September 2009; commissioning began in late April 2010 with full load on the engine in September 2010. Current feedstocks being received (equivalent to about 20,000 metric tons/year) include whey, milk products, bakery waste, dough, pet food, grease trap pumpings, glycerin, yeast, sludge from a WWTP and food waste from grocery stores and other commercial and industrial sources. The front-end of the plant includes an 80 m3 reception bunker for solid and semisolid waste, a shredder, an automatic depackaging and sorting facility (only for packaged food waste in paper and plastic), two 50 m3 receiving tanks for liquid waste streams and two 50 m3 mixing tanks, along with a hydrocyclone and a pasteurization plant and a 600 m3 acidification tank. Anaerobic digestion (AD) takes place in two 3,500 m3 CSTR digesters supplied by Entec Biogas GmbH. “The biogas production/design base was for 750 m3 biogas/metric ton volatile solids, with expected power production of 1 MW,” says Bernhard Schulz, Entec’s CEO. “Biogas production is actually 1,100 m3/metric ton VS, with current power production of 1 MW running at only half the design capacity of the plant.” The facility has a Jenbacher CHP unit, along with a biogas scrubber, gravel filter/condensate trap and a biogas cooling station.
The plant also includes a post digester, sieving station and two 8,000 m3 digestate storage tanks. Digestate is land applied as a liquid fertilizer. The plant in Benet is the first of its kind in France for food waste, adds Schulz, noting that SIFFDA plans to install two more AD plants in France in 2011.
Bangkok, Thailand, anaerobic digester
Bangkok, Thailand
The Thai Beverage Energy Co., Ltd. (TBE) recently installed anaerobic systems to treat molasses stillage at five locations throughout Thailand. A 27,000 m3 low-rate anaerobic ADI-BVF reactor was installed at each facility; the systems were completed in 2009. Interest in utilizing biogas to replace fossil fuel and other conventional energy sources brought ADI and TBE together to find a solution that would be profitable while benefiting the environment. Biogas generated from the reactors is utilized in the processing plants through a dual-fuel boiler (sediment and moisture are removed), replacing more than 80 percent of the heating energy requirements. BOD removal is approximately 90 percent. The treatment systems consist of an equalization tank, a low-rate upflow sludge bed reactor and an effluent holding pond. The low loading rate and the flocculent sludge allow the reactor to accept and treat high concentrations of degradable suspended solids and relatively high concentrations of fats, oils and grease. Raw wastewater was previously used for irrigating farmland; because there is very little nutrient removal in the anaerobic reactor, and much of the organic material is slow to degrade, the effluent continues to be valued for agricultural use.
Biogas generated from the ADI-BVF reactors exceeds the handling capacity of TBE’s existing boilers. As a result, the company is investigating options to convert the remaining biogas to electricity at its processing plants. TBE also is in the process of registering the systems with the United Nations Framework Convention on Climate Change (UNFCCC) – because of the reduction in fossil fuel usage – and expects all five projects to be registered by 2011.
Thun, Switzerland
A new anaerobic digestion plant capable of processing up to 20,000 metric tons of different substrates and conditions is under construction in Thun. The facility, using the BEKON Energy Technologies dry digestion system, includes six digesters designed to operate independently from the others. Two completely separate percolate systems have been connected to each of the digesters and each digester has been individually isolated as opposed to the normal practice of isolating in blocks of three or four digesters. Feedstocks will include yard waste (green), source separated biowaste, and organic waste from a materials recovery facility (grey). The separate percolate systems make it possible to individually control the percolation of the substrate inside each digester with either “green” percolate or with “grey” percolate, explains Nathan Dietz of Bekon. “This also allows for production of two or more grades of compost, with the highest quality compost coming from the ‘green’ material,” he says. The electricity produced from the CHP units, totaling 825 kW, will be sold to the grid; excess heat will be sold to a nearby barracks. The plant is expected to start up in December 2010.
Revel, France
The “Bio Vallée Lauragais” cluster is an integral part of the green economy that can be found in the Pays Lauragais area (southwest France), a zone with a high sustainable food production potential in the Midi-Pyrénées, the leading organic agriculture region in France. “Bio Vallée Lauragais was created to bring together various partners and cultivate innovative methods for developing businesses,” says Michel Mustin, an organic agriculture and composting consultant based in Revel. “This project is a response to the new requirements by ‘ethical consumers’ of natural and organic products.”
Fourteen companies offering a wide range of products – from pasta, bread and biscuits to tofu and innovative offerings including soybeans (via the famous white bean cassoulet) – plan to be involved. Revel has the necessary economic structures to support businesses that wish to set up shop in the Bio Vallée Lauragais. Drawing on the expertise of committed farmers and breeders – with several official French and European labels of origin and quality including Red Label and Organic European label – small and medium sized enterprises can ensure they develop while promoting the quality and biodiversity of the land. “Bio Vallée Lauragais aims to pool initiatives and driving forces to work toward sustainable development that combines authenticity and innovation,” adds Mustin. “Revel, a town on a human scale, offers a living environment near the Black Mountains Regional Park and the Canal des Deux Mers in keeping with its convictions.”

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