Environmental flows are of crucial importance for questions of sustainability. But analysing only the material side of environmental flows brings us half way understanding questions of sustainability. This article reports on the development of a more integrative approach in studying environmental impacts of agro-industrial systems in Asia, taking tapioca (cassava starch) processing in Vietnam as an example.The analysis of material flows and technological options to close material cycles is combined with an actor-network analysis from three angles: a policy, an economic and a social perspective, respectively.The paper finally assesses the additional value of the developed methodology and points out ways for further investigation and development of a more integrative approach to industrial transformations.
Abstract. The food processing sector in Vietnam plays a vital role in its economic development, but its rapid growth seems to go hand-in-hand with environmental deterioration. Several decades of applying the conventional end-of-pipe approach made clear that it only deals with treating the symptoms. It is necessary to combine technological (end-of-pipe) solutions to overcome urgent pollution problems with ways to prevent wastes from being generated or to reuse their valuable material. This article presents a methodology for analyzing the possibilities for waste prevention in food processing industry in Vietnam.
In the process of construction and development, Ho Chi Minh City is discharging about six types of sludge: 1) sludge from urban wastewater drainage systems; 2) sludge from industrial wastewater drainage system; 3) sludge from the canal dredging activities periodically; 4) sludge from septic tanks; 5) sludge from the water treatment station/plant; 6) sludge from the construction sites. Sludge's components are very different among types of sludge, sludge from the sewer network and canal dredging contain mainly sand and soil (70%-90% dry weight), while the sludge from the wastewater/water treatment station/plant and from septic tanks contain mainly biodegradable organic substances (55%-80% dry weight). The concentrations of all above-mentioned sludge (except sludge from the hazardous industrial wastewater treatment plant) are lower than toxic threshold. The volume of total sludge is about 3000-4000 m 3 /day (5000-6000 tons/day), excepting the amount of sludge generated from the water treatment plant (which is collected and treated separately). Sludge from wastewater treatment plants and septic tanks is collected, transported and recycled to become organic fertilizer. The other types of sludge are collected, transported, and disposed at the "unknown" locations, even though they have different values for use.
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