Biological nitrification and denitrification of opto-electronic industrial wastewater.
Development and application of biological nutrient removal processes accelerated significantly over the past decade due to more stringent nutrients (nitrogen and phosphorus) discharge limits being imposed on wastewater treatment plants. The opto-electronic industry has developed very fast over the past decade in the world. The wastewater often contains a significant quantity of organic nitrogen compounds and has a ratio of over 95% in organic nitrogen (Org-N) to total nitrogen (T-N). In this study, a 2-stage Anoxic/Aerobic pre-denitrification process was established and the efficiency of wastewater treatment was evaluated. Wastewater from an actual LCD-plant was obtained as the sample for looking into the feasibility of opto-electronic industrial wastewater treatment. Hydraulic retention time (HRT) and mixed liquor recycle rate (MLR) were controlled independently to distinguish between the effects of these two factors. Under suitable HRT and mixed liquor recycle ratio, effluents of NH4-N, NOx-N and COD can fall below 20 mg/l, 30 mg/l and 80 mg/l.
Factors Affecting Biological Nitrogen Removal Efficiency in a Large Wastewater Treatment Plant
The pre-denitrification method, with internal carbon source for biological nitrogen removal, has been studied in full-scale experiments at a large wastewater treatment plant (flow 130,000 m3/d). Factors controlling nitrogen removal, such as fraction of anoxic zone and organic material content in wastewater are discussed. A flexible system with fine bubble membrane disc diffusers made it possible to change the ratio between the volumes for nitrification and denitrification. The denitrification process was limited by lack of organic carbon in the wastewater and increasing the fraction of anoxic zone did not improve the efficiency of the system. With the help of on-line analysers for total nitrogen and chemical oxygen demand, the relationship between the denitrification efficiency and the carbon/nitrogen ratio has been given careful study. The average value for chemical oxygen demand after primary sedimentation was only 130 mg/l and the value for the COD/N ratio was found to be 6.3. The denitrification rate was usually in the range of 1.0 and 2.0 mg NO3-N/g MLVSS h.
Treatment of sentence production deficits in aphasia: A linguistic-specific approach to wh-interrogative training and generalization
Abstract The present research examines the effects of a linguistic-specific treatment on acquisition and generalization of wh-interrogative structures in two aphasic subjects presenting with deficit patterns consistent with agrammatism. The underlying linguistic representation of sentence structures selected for treatment and generalization was considered based on aspects of Chomsky's (1981) Government Binding (GB) theory, and a linguistic-based, wh-movement treatment strategy was implemented. Using a single-subject multiple-baseline design across behaviours and subjects, the effects of treatment were explored by examining generalization patterns across wh question forms requiring wh-movement (movement of a direct object NP to COMP). Within question form generalization also was evaluated by examining formulation of untrained sentences of varied complexity—with complexity defined in terms of the number of phrasal nodes in the d-structure representation of sentences. Results indicated that for both subjects...