Model evaluation and optimisation of nutrient removal potential for sequencing batch reactors

Performance of sequencing batch reactors for simultaneous nitrogen and phosphorus removal is evaluated by means of model simulation, using the activated sludge model, ASM2d, involving anoxic phosphorus uptake, recently proposed by the IAWQ Task group. The evaluation includes all major process configurations with different aerobic, anoxic, anaerobic sequences, and fill conditions. Basic relationships between modelling and design based on overall process stoichiometry are established for the interpretation of nutrient profiles associated with different operation modes. A similar approach is also used for the assessment of the effect of major operating parameters on system performance. WaterSA Vol.28(4) 2002: 423-43

Estimation of hazardous waste factors

The first step of establishing a reliable waste inventory is the determination of waste factors. This study presents a detailed survey for the estimation of waste factors from different manufacturing sectors. Waste factors were obtained in units of "tons of hazardous waste generated per 1 ton of production of related industry" using waste generation figures given by Turkish Statistics Institute (TURKSTAT) and production figures given by The Union of Chambers and Commodity Exchanges of Turkey (TOBB). Estimated waste factors were cross-checked with the information obtained from field surveys conducted for basic metal and metal finishing industries. The hazardous waste factors obtained from TURSTAT and TOBB data for Basic Metal Industries (37) and Manufacture of Fabricated Metal Products, Machinery and Equipment (38) are 0.0035 and 0.0068, respectively. From the field surveys, the average hazardous waste factor of eight facilitiesin category (37) is estimated as 0.054 and that for six facilities in category (38) is determined as 0.007. In a parallel evaluation, hazardous waste factors obtained from production and waste generation figures declared by nine facilities in Basic Metal category (37) and 16 facilities in Metal Finishing category (38) are calculated as 0.017 and 0.012, respectively. These varying results indicate that for reliable waste factors estimation, hazardous waste generation and production figures of the industries should be attained correctly and checked with various data obtained from different sources before they are used for establishing the waste inventories

The fate of phosphate under anoxic conditions in biological nutrient removal activated sludge systems

The nitrogen removal potential of phosphate accumulating organisms under anoxic conditions has been evaluated using a laboratory scale sequencing batch reactor fed with synthetic wastewater and operated in a sequence of anaerobic, anoxic and aerobic periods. The phosphate uptake rate under anoxic conditions was lower than that under aerobic conditions. However, in the presence of an external substrate such as glucose and acetate, the fate of phosphate was dependent on the substrate type; phosphate release occurred in the presence of nitrate as long as acetate was present and glucose did not cause any phosphate release. The nitrate uptake rate was also much lower with glucose than acetate. The results implied that poly-hydroxyalkanoates could be oxidized by nitrate and phosphate uptake during the anoxic phase should be introduced into process modeling

Model Evaluation and Optimisation of Nutrient Removal Potential for Sequencing Batch Reactors

Performance of sequencing batch reactors for simultaneous nitrogen and phosphorus removal is evaluated by means of model simulation, using the activated sludge model, ASM2d,involving anoxic phosphorus uptake, recently proposed by the IAWQ Task group. The evaluation includes all major process configurations with different aerobic, anoxic, anaerobic sequences, and fill conditions. Basic relationships between modelling and design based on overall process stoichiometry are established for the interpretation of nutrient profiles associated with different operation modes. A similar approach is also used for the assessment of the effect of major operating parameters on system performance

Insulin-like growth factor-I gene polymorphism in acne vulgaris

Background Acne vulgaris is a multifactorial disease of the skin. Several studies have shown that elevated levels of serum insulin-like growth factor-I (IGF-I) correlate with overproduction of sebum and acne. Recently functional relationship between IGF-I (CA) polymorphism and circulating IGF-I levels in adults has been reported.Aims The aim of our study was to investigate for the first time whether IGF-I (CA) polymorphism might be involved in the pathogenesis of acne or not.Methods We included 115 acne patients and 117 healthy subjects to the study. The clinical grade of acne was assessed based on the Global Acne Grading System. Participants were questioned about diabetes mellitus, PCOS and other systemic disease. We searched for the IGF-I (CA) 19 polymorphism in this study. The IGF-I (CA) 19 polymorphism was performed by polymerase chain reaction.Results We categorized the IGF-I (CA) 19 polymorphism area into three groups as lower than 192 bp, 192-194 bp and higher than 194 bp. We found that the frequency of genotype IGF-1 (CA) 19 gene was significantly different between control and acne patients (P = 0.0002). A significant association between IGF-I (CA) genotypes and severity of acne was found (P = 0.015). No significant difference was found between male and female patients (P > 0.05).Conclusions Our results suggest that IGF-I (CA) 19 polymorphism may contribute to a predisposition to acne in Turkish patients

Insulin-like growth factor-I gene polymorphism in acne vulgaris.

BACKGROUND: Acne vulgaris is a multifactorial disease of the skin. Several studies have shown that elevated levels of serum insulin-like growth factor-I (IGF-I) correlate with overproduction of sebum and acne. Recently functional relationship between IGF-I (CA) polymorphism and circulating IGF-I levels in adults has been reported. AIMS: The aim of our study was to investigate for the first time whether IGF-I (CA) polymorphism might be involved in the pathogenesis of acne or not. METHODS: We included 115 acne patients and 117 healthy subjects to the study. The clinical grade of acne was assessed based on the Global Acne Grading System. Participants were questioned about diabetes mellitus, PCOS and other systemic disease. We searched for the IGF-I (CA) 19 polymorphism in this study. The IGF-I (CA) 19 polymorphism was performed by polymerase chain reaction. RESULTS: We categorized the IGF-I (CA) 19 polymorphism area into three groups as lower than 192 bp, 192–194 bp and higher than 194 bp. We found that the frequency of genotype IGF-1 (CA) 19 gene was significantly different between control and acne patients (P = 0.0002). A significant association between IGF-I (CA) genotypes and severity of acne was found (P = 0.015). No significant difference was found between male and female patients (P > 0.05). CONCLUSIONS: Our results suggest that IGF-I (CA) 19 polymorphism may contribute to a predisposition to acne in Turkish patients