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

polymeric substances

The objective was to provide an answer to "how to grow/survive in aggregative physiology" through evaluating the relation between physical stress and observed biomass characteristics. For that, a lab-scale sequencing batch reactor was operated at an anaerobic-aerobic mode and under altered hydraulic selection pressures of settling time (10-1 min) and hydrodynamic shear rates due to mechanical mixing (15.5-12.0 cm/s) and/or aeration (1.76-0.24 cm/s). Main physical stress experienced by the biomass was mechanical mixing, which resulted in extreme shearing conditions at the first operational stage (days 1-86), during which first granules formed but settling properties deteriorated and biomass was almost totally washed out. After relaxing the overall shear stress at the second stage, biomass formation accelerated, settling properties enhanced and granulation proceeded (days 86-136), until disturbance of the process at the last month of operation (days 136-163). Aggregative physiology-related parameters, being cell surface hydrophobicity and extracellular polymeric substances (EPS), followed increasing trends parallel to the progress of granulation, and then decreased upon disturbance of the process. There was an increase in the EPS production also during the first stage under extreme shear, while a substantial amount of biomass was present in the system. A direct correlation was also found between % hydrophobicity and EPS-composition expressed as ExoPN/ExoPS

treatment systems: drawbacks of existing prescriptions

The paper reviews and evaluates the basic steps in designing activated sludge systems based on process stoichiometry and mass balance. Appropriate system design requires the use of biodegradable COD as the main parameter, which sets a balance between substrate utilized, biomass generated and oxygen consumed. In practice, this balance is easily translated into excess sludge production and oxygen requirement. The evaluation first covers the necessary database for a rational design approach, with emphasis on relevant domestic wastewater characterization. Then it defines the excess sludge production, together with the daily oxygen demand. Principles outlined are illustrated in a numerical design example where the proposed rational approach is compared with the German Design Guidelines, A-131 for organic carbon removal

How does shear affect aggregation in granular sludge sequencing batch reactors? Relations between shear, hydrophobicity, and extracellular polymeric substances.

The objective was to provide an answer to "how to grow/survive in aggregative physiology" through evaluating the relation between physical stress and observed biomass characteristics. For that, a lab-scale sequencing batch reactor was operated at an anaerobic-aerobic mode and under altered hydraulic selection pressures of settling time (10-1 min) and hydrodynamic shear rates due to mechanical mixing (15.5-12.0 cm/s) and/or aeration (1.76-0.24 cm/s). Main physical stress experienced by the biomass was mechanical mixing, which resulted in extreme shearing conditions at the first operational stage (days 1-86), during which first granules formed but settling properties deteriorated and biomass was almost totally washed out. After relaxing the overall shear stress at the second stage, biomass formation accelerated, settling properties enhanced and granulation proceeded (days 86-136), until disturbance of the process at the last month of operation (days 136-163). Aggregative physiology-related parameters, being cell surface hydrophobicity and extracellular polymeric substances (EPS), followed increasing trends parallel to the progress of granulation, and then decreased upon disturbance of the process. There was an increase in the EPS production also during the first stage under extreme shear, while a substantial amount of biomass was present in the system. A direct correlation was also found between %hydrophobicity and EPS-composition expressed as ExoPN/ExoPS

EFFECT OF CHEMICAL TREATMENT ON THE AROMATIC CARBON CONTENT AND PARTICLE

The present experimental work was carried out to examine the physicochemical treatability of a high-strength olive oil mill wastewater (OMW). Firstly, the wastewater was subjected to environmental characterization and particle size distribution-based COD-TOC-UV254-UV280 analyses. The following treatment schemes were selected for the study: Coagulation-flocculation in the presence of anionic and commercial polymers at varying pH and coagulant/polymer dosages Fenton treatment at different pH's and Fe(II): H2O2 concentrations as well as electrocoagulation using stainless steel electrodes at different electrolyte concentrations and current densities. Results of the study have indicated that none of the investigated physicochemical treatment methods was capable of removing the organic carbon content of the wastewater by more than 30% in terms of COD and 20% in terms of TOC that is at least partially attributable to the high, soluble organic carbon content of the wastewater. Alternative treatment processes and/or combinations have to be explored for effective treatment of OMW effluent

treatment systems: drawbacks of existing prescriptions

The paper reviews and evaluates the basic steps in designing activated sludge systems based on process stoichiometry and mass balance. Appropriate system design requires the use of biodegradable COD as the main parameter, which sets a balance between substrate utilized, biomass generated and oxygen consumed. In practice, this balance is easily translated into excess sludge production and oxygen requirement. The evaluation first covers the necessary database for a rational design approach, with emphasis on relevant domestic wastewater characterization. Then it defines the excess sludge production, together with the daily oxygen demand. Principles outlined are illustrated in a numerical design example where the proposed rational approach is compared with the German Design Guidelines, A-131 for organic carbon removal

engineering

The paper evaluates the scientific merit of doctoral studies on environmental sciences and technology, involving completed doctoral studies in Turkey between 2000-2007, as a case study. The investigation revealed 446 scientific papers derived from 170 completed doctoral studies. This level represented 22% of the total number of publications at departments with graduate programs in this field. 42 of the completed studies (25%) did not produce published papers other than the compulsory doctoral thesis. These publications received 2766 citations, corresponding to 6.2 citations per publication; 65 of 170 doctoral studies completed (38%) had no record of any citation, indicating that aside from 42 doctoral theses which did not produce any publications, results of 22 doctoral studies were published but received no citations. Impact factors of selected journals for publication varied within a wide range of 0.429 to 3.894 with an average value of 1.65, based on 2007 impact factor records