• Journal of Environmental Science International
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• v.3 no.3
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• pp.273-284
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• 1994

The primary objective of this study was to examine the toxic effects of PCP on activated sludge and to analyze its metabolic responses while treating wastewater containing pentachlorophenol (PCP) in a sequencing batch reactor (SBR) system operating under different control strategies. This study was conducted in two phases 1 and 2 (8-hr and 12-hr cycles). Each phase was operated with two control strategies I and II. Strategy I (reactor 1) involved rapid addition (5 minutes to complete) of substrate to the reactor with continuous mixing but no aeration for 2 hours. Strategy ll (reactor 2) involved adding the feed continuously during the first 2 hours of the cycle when the system was mixed but not aerated. During both phases each reactor was operated at a sludge age of 15 days. The synthetic wastewater was used as a feed. The COD of the feed solution was about 380 mg/l. After the reference response for both reactors was established, the steady state response of each system was established for PCP feed concentrations of 0.1 mg/l, 1.0 mg/l, and 5.0 mg/l in SBR systems operating on both 8-hr and 12-hr cycles. Soluble COD removal was not inhibited at any feed PCP concentrations used. At 5.0 mg/l fined PCP concentration and in SBR systems operating on phase 2, the concentrations of MLVSS were decreased; selective pressure on the mixed biomass might be increased, narrowing the range of possible ecological responses; the settleability of activated sludge was poor; the SOURS were increased, showing that the systems were shocked. Nitrification was made to some extent at all concentrations of feed PCP in SBR systems operating on phase 2 whereas in SBR systems operating on phase 1 little nitrification was observed. Then, nitrification will be delayed as much as soluble COD removal is retarded due to PCP inhibition effects. Enhanced biological phosphorus removal occurring in the system operating with control strategy I during phase 1 of this work and in the presence of low concentrations of PCP was unreliable and might cease at anytime, whereas enhanced biological phosphorus removal occurring in the system operating with either control strategy I or II during phase 2 of this work and in the Presence of feed PCP concentrations up to 1.0 mg/l was reliable. When, however, such processes were exposed to 5.0 mg/l PCP dose, enhanced phosphorus removal ceased and never returned.

• Korean Journal of Soil Science and Fertilizer
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• v.11 no.3
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• pp.145-160
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• 1979

The effects of organic material application on soil physical properties were reviewed in relation to soil productivity. The organic matter contents and soil physical properties of the cultivated land in Korea were summarized and the effects of organic matter were compared in terms of land uses and soil types. Soil physical properties related to crop yield potential, such as soil aggregation, permeability, water holding capacity, erodibility, and compactibility, were used in evaluating the effects of organic materials as a soil physical amendment. The benefical effects of organic matter addition on soil physical conditions include (1) better aeration and increased infiltration in silty and clayey soils, (2) increased water holding capacity and moisture availability in sandy soils, (3) decreased soil erodibility, and (4) increased resistance to compaction. It is, therefore, concluded that continuous application of organic materials could greatly improve the various soil physical properties and favor the growth and yield of crops. A high rate of organic matter addition could contribute to reducing not only the soil erosion on sloping land, but also the possible detrimental effect of farm mechanization. In general, the effects of organic matter on soil physical improvement were estimated to be much higher in upland than in paddy. Organic matter would have a more pronounced effect on low productive lands such as heavy clayey or sandy soils and newly reclaimed soil. The optimum level of soil organic matter content was estimated to be about 3.0 to 3.5% for the best soil physical condition. Since the organic matter contents of the cultivated lands in Korea are much lower than optimum level, it would be desiable to use more organic materials to soil for the increase of soil productivity, continuation of stabilized high productivity and soil erosion control.

• Journal of Aquaculture
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• v.6 no.4
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• pp.323-338
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• 1993

The primary objective of this study was to examine the toxic effects of PCP on activated sludge and to analyze its metabolic responses while treating wastewater containing pentachlorophenol (PCP) in a sequencing batch reactor (SBR) system operating under different control strategies. This study was conducted in two phases 1 and 2 (8-hr and 12-hr cycles). Each phase was operated with two control strategies I and II. Strategy I (reactor 1) involved rapid addition (5 minutes to complete) of substrate to the reactor with continuous mixing but no aeration for 2 hours. Strategy II (reactor 2) involved adding the feed continuously during the first 2 hours of the cycle when the system was mixed but not aerated. During both phases each reactor was operated at a sludge age of 15 days. The synthetic wastewater was used as a feed. The COD of the feed solution was about 380 mg/L. After the reference response for both reactors was established, the steady state response of each system was established for PCP feed concentrations of 0.1 mg/L, 1.0 mg/L, and 5.0 mg/L in SBR systems operating on both 8-hr and 12-hr cycles. Soluble COD removal was not inhibited at any feed PCP concentrations used. At 5.0 mg/L feed PCP concentration and in SBR systems operating on phase 2, the concentrations or ML VSS were decreased; selective pressure on the mixed biomass might be increased, narrowing the range of possible ecological responses; the settleability of activated sludge was poor; the SOURs were increased, showing that the systems were shocked. Nitrification was made to some extent at all concentrations of feed PCP in SBR systems operating on phase 2 whereas in SBR systems operating on phase 1 little nitrification was observed. Then, nitrification will be delayed as much as soluble COD removal is retarded due to PCP inhibition effects. Enhanced biological phosphorus removal occurring in the system operating with control strategy I during phase 1 of this work and in the presence of low concentrations of PCP was unreliable and might cease at anytime, whereas enhanced biological phosphorus removal occurring in the system operating with either control strategy I or II during phase 2 of this work and in the presence of feed PCP concentrations up to 1.0 mg/L was reliable. When, however, such processes were exposed to 5.0 mg/L PCP dose, enhanced phosphorus removal ceased and never returned.