International meeting in Japan assembles researchers, project managers and equipment suppliers to promote "environmentally sound utilization of organic materials."
THE INTERNATIONAL Symposium of Biorecycling/Composting - held September 6-8, 1999 in Sapporo - provided a portrait of the status of organic residuals utilization in Japan. The following data is excerpted from the Symposium Proceedings.
According to a presentation by Mitsu Chino of the University of Tokyo (who chaired the meeting's Executive Committee), 280 million tons of organic residuals are discarded annually in Japan, representing 60 percent of the total solid waste generated. "We estimate that the organic material contains a nitrogen fertilizer equivalent of 1.32 million tons, phosphorus of 0.62 million tons, and potassium of 0.65 million tons," explains Chino. But most urban wastes are incinerated or landfilled, even though their N-- P-K value could satisfy the needs of Japanese farmers.
Annual production of woody residuals such as bark, sawdust and chips amounts to 5.47 million tons; about 95 percent is used effectively for pulp production, fuel, livestock bedding, bulking agents, etc. But yard trimmings - about 2.5 million tons/year - are mostly incinerated or landfilled.
The amount of compost produced as well as the number of facilities have been increasing steadily. While the rate of increase has slowed since 1990, the annual volume of compost produced has grown from less than 600,000 tons in 1979 to 3 million tons in 1996. "Production of bark compost and cattle manure compost especially has greatly increased recently," concludes Chino. "In Japan, incineration and landfilling systems are widely adopted for disposal of organic wastes. However, there is a concern that the system may cause various problems, namely, a generation of toxic substance like dioxin."
Status of sludge composting
In his report, "Status of Sewage Sludge Composting in Japan and Future Strategy," Kazuaki Sato of the Water Quality Control Department in Tukuba said that 1.7 million tons of dry solids were generated in fiscal 1995. Final stabilized forms were 22.7 percent as dewatered solids, 9.2 percent as compost, 1.4 percent as dried sludge, 60.8 percent as incinerated ash and 5.3 percent as melted slag. The incinerated sludge amounts to 1 million tons. Almost 67 percent of sludge solids are landfilled; 13.4 percent are used in agricultural and landscape plantings; 16.7 percent of the slag and ash as construction materials; and 1.2 percent is dumped in the ocean
In 1996, Sato and his colleague Hiroaki Morita identified 298 local public agencies that applied sewage sludge to land as fertilizer or soil conditioner, plus some private companies that used sludge to produce organic fertilizer. Kagoshima City was cited as the municipality producing the largest amount of biosolids compost at 15,200 tons/year. Included in their list of 33 biosolids composting facilities as of 1996 were Akita, Sapporo, Tendo, Turuok, Mobara, Kofu, Yamagata, Fukuoka, Shinliko and Gojogawa.
Yamagata was described as an example of a city that took steps to reduce heavy metal content when it commissioned a composting plant in 1980. Before the project began, mercury content in sludge was 5 mg/kg, far higher than the level of 2 mg/kg stipulated in the Fertilizer Control Law.
Domestic wastewater accounts for 95 percent of the municipal wastewater generated in the city, with only a small percentage produced by factories since there are very few manufacturing facilities that discharge heavy metals. This implies that the heavy metals in the municipal wastewater were from medical treatment facilities.
The wastewater management division of the city therefore implemented a number of measures to reduce the heavy metals content in the wastewater discharged by medical facilities such as hospitals, clinics, and dental offices. First, it asked the city medical offices, hospital, and dental associations to replace chemicals containing heavy metals; to try to recover the mercury before destroying thermometers, hemomanometers, and other medical equipment containing mercury; and to stop using liquid mercuric chloride and mercuro-chrome as disinfectants. Because dentists use an amalgam made of a mercury-tin alloy for fillings, they were asked to install pretreatment facilities (settling chambers) to prevent powdered amalgam from flowing directly into the municipal wastewater system along with the water drained during drilling. These measures have sharply reduced the mercury content of the sewage. This approach to reducing heavy metal content has been followed by several other municipalities. "Administrative efforts of this kind are essential to promote the recycling of sewage sludge for agriculture and landscape planting," note Sato and Morita.
Recreating a "circulation" system
Several researchers from Kyoto University - M. Naito, T. Kusube and Y. Yang - presented a concept for the "Reconstruction of a Regional Recycle System of Organic Materials." They propose to set up a circulation system that would link households, the food industry, the livestock industry and agriculture. The difficulties in achieving an "urban/rural complex" that would lead to "man and nature in symbiosis" are spelled out by the authors, ranging from the food import polices of the nation to the lifestyles of individual households.
To develop their recycling models, the authors assembled data on quantities of organic residuals from food industries, distances to transport materials from generation site to composting (or other reuse) facility, comparing CO2 emissions from transport of by-products, and potential benefits from composting and a method identified as "thermophilic toxic process." Livestock industry residuals
Composting technology for animal wastes was discussed by K. Haga of the National Institute of Animal Industry in Tsukuba, who stated that about 90 million tons/ year are generated. "The number of complaints per farm has been increasing, suggesting that the problems are becoming increasingly more complicated and serious for each farm," Haga noted. "... Composting is the main treatment method for solid wastes of dairy cattle, beef cattle and pigs. Layer droppings are dried, and broiler litter is used without any treatment because it has already dried in the housing. It is difficult to spread slurry to most cropland in Japan, except a part of Hokkaido where large-scale dairy farming is popular."
Further information specifically on use of cattle wastes in dairy farming in Hokkaido was given by T. Matsunaka of Rakuno Gakuen University. Almost 900,000 dairy cattle are raised in Hokkaido, producing 12 million tons of manure and 4 million tons of urine. He pointed out the problems of applying animal wastes on dairy farms with more than 100 cows because of very short application times caused by weather. "It is therefore an urgent priority to develop machinery that can apply the large quantity of wastes to grassland in an environmentally acceptable way during the limited time available," sums up Matsunaka.
Commercial organics recycling systems
Other equipment needs and developments with commercial systems for processing organic residuals were described at the symposium.
Roundtrip Paddling Fermentor - Made by the Ebara Corporation, this unit uses a paddle traveling in a zig-zag direction to mix large volumes of materials within a smaller area than conventional fermentors. The paddling system is designed to "soften" materials and prevent clumping to provide uniform air distribution. The system also uses a Selective Pulverizing Classifier which consists of a rotary drum screen and turning scraper for processing the compostable fraction of MSW.
According to Tom Hennessey of the Miller Composting Corporation, which represents the Ebara technology in North America, there are 20 sites in Japan using Ebara compost systems. For more details, Hennessey can be reached at (905) 475-6356 or email tomh@millergroup.ca.
Green Gaia System - Kiyomoto Bio developed the Green Gaia method to process organic industrial residuals in joint research with Dr. Kuroda of Miyazaki University. The system utilizes nitrogen fixation microbes. The system has been set up at a municipal sewage treatment plant in Nobeoka, Miyazaki as well as at a compost facility in Akkeshi, Hokkaido. For additional details contact Kiyomoto Bio Co., Ltd., 1-9-2 Gakuenkibanadai, Miyazaki 889-2152, Japan.
Managing Cattle Slurry - Researchers with the Kubota Corporation studied the relationship between BOD volumetric loading and BOD/nitrogen removal efficiency to improve composting of liquid manures. For more information, contact the Technology Development Laboratory, Kubota Corporation, 2-47 Shikitsuhigashi 1-chome, Naniwa-ku, Osaka, Japan 556-8601; ph. 816 66482111; fax 816 66483862.
Microbial Degradation Analyzer - The combined work of staff at the University of Shizuoka, Fuji Industrial Research Institute and Saida Ironworks Company led to development of an apparatus to evaluate microbial degradability of biodegradable plastics, organic industrial residuals and such material as PCBs. The apparatus - called Microbial Oxidative Degradation Analyzer - comprises a reaction column maintained constantly at a fixed temperature, means for forming saturated water vapor, and an adsorption column. For information on the concept and analyzer unit, contact K. Hiyoshi, Fuji Industrial Research Institute of Shizuoka Prefecture, Fuji-shi 417-8550, Japan.
Integrating Compost Processes - Nishihara Environmental Sanitation Research Corporation notes that most conventional composting facilities carry out pretreatment, fermentation and "product-making" using separate equipment. Its system, according to the company, integrates the processes and is designed for medium and large-scale water treatment facilities; "the turning, transfer, mixing and agitation of feedstocks can be carried out by the one unit." The system has been tested at the Shikaoi experimental station.
Oil Treatment Dehydration - The principle of this Prorex system is "the same as that of tempura," deep frying in an oil bath, explain researchers at the company. Raw organic materials are heated and dehydrated under reduced pressure in an oil bath vessel. After dehydration, the solids are separated from the oil. Products can be utilized as animal feed, organic fertilizers and fuel. Prorex reports construction of 59 plants from 1974 to 1999, with five underway as of June, 1999. For technology information, contact Prorex Company, Ltd., Fukuoka, Japan.
Treating Livestock Manure And Waste Wood - According to the department chiefs in Environmental Systems and Corporate Planning at Fuji Car Mfg. Co. in Osaka (2-3 Nishi-Shinsaibashi 2chome, Chuo-ku, Osaka Japan 542-0086. ph. 816 21 32711), "Fuji Car has been constructing plants for kitchen waste and excreta of livestock since 1970 in these places in Japan: Saga City, Toyohashi City, Tahara Town, Asahli & Kawagoe Towns, Takayama Village, Dairy at Oka Area and Miura City. The closed system uses a "Boden Filter" to ferment organic materials under aerobic conditions in a vertical multistage unit. The 12 tpd manure composting plant in the Qka Area is operated by a cooperative association of seven local dairy farmers, occupies 2,300 cubic meters, and cost 167 million yen. The Fuji Car Company also makes a refuse collection vehicle equipped with a grinder for chipping pruned branches. The composting plant in Matsuto City now uses rice hulls as a bulking agent.
Intermittent Ventilation Container -The Maezawa Industry Company has tested an intermittent ventilation controlled container-type compost system for sludge cake. The company provides this process description: Supplied air is ventilated homogeneously by a special screen at the bottom of the container. In this system, the odor emitted in the fermentation process is absorbed by the exhaust blower without leaking outside, and exhausted after passing through the container filled with bark manure and compost. For details on equipment structure and operation, contact Maezawa Industry Co. Ltd., Environmental Business Headquarters, Tokyo, Japan.
Commercial Garbage Composter - Executives of Matsushita Electric Works, Ltd. (1048, Oaza Kadoma, Kadoma City, Osaka, 571-8686 Japan. ph. 816 6908 1131) reported that the company has obtained ISO 14001 certificates at its headquarters and all 15 factories in Japan. "We are creating new products that are environmentally friendly. A residential garbage processor which biodegrades food residuals is one of them and has been on the market for five years," they stated. The unit uses "bio-tips" that serve as habitats for microorganisms. The composter has an "emission control system" with a heat exchanger and blower. Matsushita Electric Works Ltd. will be using this processor at all of its plants to "achieve zero waste emission." New processors for 50 kg and 100 kg/day will be marketed in 2000. "We intend to solve garbage treatment issues widely and successfully to contribute to environmental protection," sum up Matsushita executives.
Mobile Grinder for Soil Improvement-- Komatsu, Ltd. (3-6, Akasaka 2-chome, Minato-ku, Tokyo, 107-8414 Japan, ph. 81 3 5561 2604) has developed what it calls the "Gara-Pagos" series to recycle construction and demolition debris. "Regarding soil improvement," explains Akihito Taguchi of Komatsu, "we have developed the mobile soil improver, Gara-Pagos Reterra." To recycle wood waste (i.e., thinnings, stumps, etc.) , Komatsu reports that it has also developed a mobile tub grinder, which can produce chips for use in composting, fuel and pulp materials. "Through the Gara-Pagos series and environmental engineering business, we have an eye on being a company that contributes to global environmental conservation," emphasizes Komatsu executives.
Rotary, Enclosed Composter - According to the Narasaki company, its "Hakko Ace" horizontal, rotary, enclosed equipment can compost many different feedstocks, offering both primary and secondary fermentation. In its rotary cylinder unit, temperatures reach 50'C to 80 deg C; materials take about three days from input to exit; volume is reduced about 40 to 60 percent; moisture is reduced about 35 to 50 percent, and a high quality compost is produced.
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