Households, agriculture, industry, fishing, and fish farming along Imbang River, Negros Occidental
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Interviews were conducted among respondents identified from the households, agriculture farms, sugar mills, and fish farms along the whole stretch of Imbang River, Malisbog River, and Muyao Creek, down to Barangay Balaring at the coast of Silay City in Negros Occidental. Among the 1,073 households, 11% used river water for washing clothes, but 20% also used the rivers for disposal of waste waters, 11% for human wastes, and 13% for animal wastes. Among the 30 respondents from the agriculture sector, 70% discharged water into the river. The two sugar mills in the area treated waste waters partially before release into the rivers; one sugar mill also released wastes in a nearby rice field. Milling wastes such as bagasse, molasses, and mud press were reused and not dumped into the river. Imbang River was both the water source and wastewater sink for seven fish farms.
Sanares, R. C. (2008). Households, agriculture, industry, fishing, and fish farming along Imbang River, Negros Occidental. In T. U. Bagarinao (Ed.), Research Output of the Fisheries Sector Program (Vol. 2. Reports on Fisheries and Aquaculture, pp. 83-86). Quezon City, Philippines: Bureau of Agricultural Research, Department of Agriculture.
PublisherBureau of Agricultural Research, Department of Agriculture
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Book chapterGA Gonzales - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of AgricultureDomestic effluents, or waste waters from human settlements, were sampled from eight stations along Imbang River in Negros Occidental from July 1993 to February 1995. Three types of domestic waste waters were produced by communities along Imbang River. Waste waters from clothes washing, house cleaning, and bathing, including washings of domestic animals and holding pens and run-off from rains and storms were conveyed by open canals and ditches to the river. This type of domestic effluents were well aerated and had the least potential to degrade the rivers. Waste waters from kitchens and markets carried large volumes of food scraps and other solid wastes, were unsightly, and smelled bad from the decomposition of garbage. Overflows from septic tanks were the most objectionable domestic effluents with offensive visual and olfactory properties. Domestic effluents had pH 4–7.6, dissolved oxygen of 0.5–7.2 ppm, and biochemical oxygen demand ranging from 2 to 240 ppm. The overflows from septic tanks were of the worst quality, with BOD 20x greater than household washings, and 6x more than kitchen and market effluents. Fecal coliform bacteria made up 93% of the total coliforms in the septic tank overflows, 86% in kitchen and market waste waters, and 39% in household washings. The domestic effluents from the communities around Imbang River had higher than allowable levels of BOD and solids. The 11 barangays with 16,486 households and 85,535 people loaded about 3,4000 m3 of waste water into the river every day. Along with the waste water were 180 mt/yr of BOD, 590 mt/yr of total solids, plus large quantities of nutrients, surfactants, and fecal coliform bacteria.
Book chapterM Troell, N Kautsky, M Beveridge, P Henriksson, J Primavera, P Rönnbäck & C Folke - In SA Levin (Ed.), Encyclopedia of Biodiversity, 2013 - Academic PressBiophysical impacts of aquaculture, with consequences for biodiversity, vary with species and culture systems and include issues such as: nutrient enrichment/removal, chemicals, land use, species introductions, genetic flow to wild populations, disturbance of balance or introduction of pathogen/parasites, consumption of capture fishery resources, energy, and greenhouse gas emissions. Guiding principles, labeling schemes and various tools are needed to analyze performance and conformance. Ecological footprints and life-cycle analysis aim to capture biophysical performance, including up- and downstream effects of policy decisions. Aquaculture provides a range of services but also makes demands and impacts on ecosystem functions, services, and thus biodiversity.
Book chapterHJ Gonzales - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of AgricultureThe effluents of two sugar mills and the effects on water quality in the receiving rivers were studied. Sugar mill A was located in Barangay Dos Hermanas in Talisay and discharged directly into Imbang River. Sugar Mill B was located in Barangay Hawaiian in Silay City and discharged into Malisbog River, a tributary of Imbang. Both sugar mills had sedimentation tanks and lagoons for partial wastewater treatment prior to discharge. Water sampling was done at 13 stations at effluent discharge sites and also upstream and downstream of these sites. The sugar mill effluents were particularly high in biochemical oxygen demand (BOD 109–419 mg/l), total suspended solids (168–384 mg/l), and total solids (1,185–1,234 mg/l), also high in ammonia (0.2–0.5 mg/l) and water temperature (31–38°C), but low in dissolved oxygen (2–5 mg/l). Measured stream flows varied at the different stations and were generally lowest at stations near sugar mill A and at stations near sugar mill B. At these sites, the depth of Imbang River varied from about 10 cm during low water flow in December–May to about 2 m during high water flow in June–November. During normal low flows, the sugar mill effluent comprised 75–85% of the total stream volume, causing highly polluted conditions immediately below the outlets. Sugar mill A discharged high annual loads of solids, BOD, nitrate, and phosphate into Imbang River, whereas sugar mill B loaded plenty of solids, BOD, ammonia, and phosphate into Malisbog River. The sugar cane milling season in Negros Occidental started in October and ended in May, coincident with the dry season. Significantly higher levels of BOD and nutrients, but lower DO, were observed in the river during the milling season (see figures in Gonzales et al., this volume), both because of greater discharge and lower dilution by lower stream flows. River water quality was better at the stations upstream than downstream of the sugar mills. Stations near the sugar mills had BOD, ammonia, and solids at concentrations exceeding the allowable limits set for river water by the Department of Environment and Natural Resources.