Bio: Sibel Basakcilardan-Kabakci is an academic researcher from Istanbul Technical University. The author has contributed to research in topics: Struvite & Mass transfer coefficient. The author has an hindex of 4, co-authored 4 publications receiving 168 citations.
TL;DR: In this article, the removal and recovery of ammonia from urine by stripping and absorption processes was investigated, where ammonia was stripped with air in a batch system and absorbed in a sulphuric acid solution.
Abstract: Separately collected human urine contains valuable nutrients including nitrogen, phosphorus, and potassium This study concerns the removal and recovery of ammonia from urine by stripping and absorption processes Throughout the experiments, ammonia was stripped with air in a batch system and absorbed in sulphuric acid solution Combined mass transfer coefficient (KL × a) for urine–air interaction, was calculated for different pH levels and air flow rates, by using a spherical stripping unit equipped with a ceramic fine-pore air stone (average pore size 40 microns) (KL × a) was observed to increase with increasing pH level and air flow rate The highest value of combined mass transfer coefficient was 048 h−1 , obtained at a pH of 12 and an air flow rate of 027 m3/h In the stripping process, a direct relationship was observed between air flow rate and mass transfer rate At an air flow rate of 021 m3/h, and at pH 12, the highest mass transfer rate (0085 g/h) was obtained In the absorption unit, aver
TL;DR: Tetracycline removal by adsorption was affected by solution pH, contact time, and struvite concentration, and the amount of tetracyCline adsorbed on the surface was low because of the electrostatic repulsion, and Freundlich and Redlich-Peterson models best defined the equilibrium data.
Abstract: The interaction of tetracycline with struvite during adsorption and precipitation processes was investigated. Tetracycline removal by adsorption was affected by solution pH, contact time, and struvite concentration. The lowest tetracycline removal (8.4%) was observed at pH 7.7, the dissociation constant (pKa(2)) of tetracycline. Because of the electrostatic repulsion, the amount of tetracycline adsorbed on the surface was low. The small amount of adsorption was the result of surface complexation between tetracycline ions and metal ions. Calcium (Ca2+) ions in the adsorbent enhanced the binding of tetracycline. Freundlich (K-F: 0.04, n: 1.49) and Redlich-Peterson (K-R: 0.08, alpha(R): 0.98, beta(R): 0.49) models best defined the equilibrium data. In the case of struvite precipitation, approximately 22% of tetracycline was removed as a result of binding to struvite alongside struvite formation.
TL;DR: Overall rating value (ORV) calculates and quantifies the waste as regular, non-regular or hazardous waste in an "hourglass" scale to ease the works of decision makers in managing the wastes.
Abstract: Although hazardous waste lists and their classification methodologies are nearly the same in most of the countries, there are some gaps and subjectiveness in determining the waste as hazardous waste. A rating system for the determination of waste as a hazardous waste is presented in this study which aims to overcome the problems resulted from the existing methodologies. Overall rating value (ORV) calculates and quantifies the waste as regular, non-regular or hazardous waste in an “hourglass” scale. “ORV” as a cumulative-linear formulation in proposed model consists of components such as ecological effects of the waste (Ee) in terms of four main hazard criteria: ignitability, reactivity, corrosivity and toxicity; combined potential risk (CPR) including carcinogenic effect, toxic, infectious and persistence characteristics; existing lists and their methodology ( L ) and decision factor ( D ) to separate regular and non-regular waste. Physical form ( f ) and quantity ( Q ) of the waste are considered as factors of these components. Seventeen waste samples from different sources are evaluated to demonstrate the simulation of the proposed model by using “hourglass” scale. The major benefit of the presented rating system is to ease the works of decision makers in managing the wastes.
TL;DR: In this paper, the effect of reaction time, reaction pH, and initial mg:P ratio on struvite precipitation was investigated, and it was shown that reaction time had negligible effect on phosphate removal, and pH influenced both phosphate removal efficiency and the composition of the precipitate.
Abstract: Struvite precipitation is an effective process for removing and recovering phosphate from separately collected fresh urine. Present study experimentally investigated the effect of reaction time, reaction pH, and initial molar Mg:P ratio on struvite precipitation. Results showed that reaction time had a negligible effect on phosphate removal, and pH influenced both phosphate removal efficiency and the composition of the precipitate. Precipitates obtained at pH 9 were crystalline struvite which was confirmed by the FTIR and X-ray diffraction analysis. Studying at a molar ratio below 1Mg:1P enhanced the formation of amorphous calcium phosphate and decreased the purity of the precipitate with respect to struvite. Struvite precipitation from fresh urine (1.57 Mg:1P) achieved at pH 9 in 1-h reaction time resulted in 96% of PO43−–P and 52.5% of NH3-N removal. High phosphate recovery obtained in this experimental study indicated that combining urine separation with struvite precipitation is a promising idea towar...
TL;DR: This review brings up important questions that are still open, and addresses some significant issues which must be tackled in the future for a better understanding of the behavior of antibiotics in the environment, as well as the risks associated with their occurrence.
Abstract: Although antibiotics have been used in large quantities for some decades, until recently the existence of these substances in the environment has received little notice. It is only in recent years that a more complex investigation of antibiotic substances has been undertaken in order to permit an assessment of the environmental risks they may pose. Within the last decade, an increasing number of studies covering antibiotic input, occurrence, fate and effects have been published. Antibiotics are one of the most important groups of pharmaceuticals. Antibiotic resistance is one of the major challenges for human medicine and veterinary medicine. However, there is still a lack of understanding and knowledge about sources, presence and significance of resistance of bacteria against antibiotics in the aquatic environment despite the numerous studies performed. This review summarizes this topic. It names important open questions and addresses some significant issues which must be tackled in the future for a better understanding of resistance related to antibiotics in the environment.
01 Jan 2004
TL;DR: In this paper, the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance, are investigated and the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable.
Abstract: Antibiotics, disinfectants and bacteria resistant to them have been detected in environmental compartments such as waste water, surface water, ground water, sediments and soils. Antibiotics are released into the environment after their use in medicine, veterinary medicine and their employment as growth promoters in animal husbandry, fish farming and other fields. There is increasing concern about the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects. Increasingly, antibiotic resistance is seen as an ecological problem. This includes both the ecology of resistance genes and that of the resistant bacteria themselves. Little is known about the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance. According to the present state of our knowledge, the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable. The input of resistant bacteria into the environment seems to be an important source of resistance in the environment. The possible impact of resistant bacteria on the environment is not yet known. Further research into these issues is warranted.
TL;DR: Factors that influence antibiotic effects on microbial communities in soil and aquatic environment are discussed, including concentration of antibiotics, exposure time, added substrates, as well as combined effects of multiple antibiotics.
Abstract: Antibiotics act as an ecological factor in the environment that could potentially affect microbial communities. The effects include phylogenetic structure alteration, resistance expansion, and ecological function disturbance in the micro-ecosystem. Numerous studies have detected changes of microbial community structure upon addition of antibiotics in soil and water environment. However, the causal relationship between antibiotic input and resistance expansion is still under debate, with evidence either supporting or declining the contribution of antibiotics on alteration of antibiotic resistance. Effects of antibiotics on ecological functions have also been discovered, including nitrogen transformation, methanogenesis, and sulfate reduction. In the latter part, this review discusses in detail on factors that influence antibiotic effects on microbial communities in soil and aquatic environment, including concentration of antibiotics, exposure time, added substrates, as well as combined effects of multiple antibiotics. In all, recent research progress offer an outline of effects of antibiotics in the natural environment. However, questions raised in this review need further investigation in order to provide a comprehensive risk assessment on the consequence of anthropogenic antibiotic input.
TL;DR: The results indicate that electrostatic adsorbent-adsorbate interactions play an important role in TC adsorption processes when conducted at pH values that produce TC deprotonation.
Abstract: The objective of this study was to analyze the behavior of activated carbons with different chemical and textural natures in the adsorption of three tetracyclines (TCs) (tetracycline, oxytetracycline, and chlortetracycline). We also assessed the influence of the solution pH and ionic strength on the adsorption of these compounds and studied their removal by the combined use of microorganisms and activated carbon (bioadsorption). Sludge-derived materials were also used to remove TC from water. The capacity of these materials to adsorb TC was very high and was much greater than that of commercial activated carbon. This elevated adsorption capacity (512.1–672.0 mg/g) is explained by the high tendency of TC to form complex ions with some of the metal ions present in these materials. The medium pH and presence of electrolytes considerably affected TCs adsorption on commercial activated carbon. These results indicate that electrostatic adsorbent–adsorbate interactions play an important role in TC adsorption processes when conducted at pH values that produce TC deprotonation. The presence of bacteria during the TCs adsorption process decreases their adsorption/bioadsorption on the commercial activated carbon, weakening interactions between the adsorbate and the microfilm formed on the carbon surface. The adsorptive capacity was considerably lower in dynamic versus static regime, attributable to problems of TC diffusion into carbon pores and the shorter contact time between adsorbate and adsorbent.
TL;DR: This paper addresses the issue of phosphorous losses across the world by reviewing key aspects relevant to process design to pave the way for future application and provides comprehensive information that is essential for future industrial struvite crystallization process design.
Abstract: Phosphorous (P) is an essential element for living organisms and is predicted to be depleted within the next 100 years. Across the world, significant phosphorous losses due to its low utilization efficiency become one of the main reasons for water pollution. Struvite crystallization has been found to be a promising recovery technique to mitigate these problems, as the recovered precipitate can be used as a slow release fertilizer or raw material for chemical industry. Although this technique has been widely investigated over the past two decades, there are currently few real applications in industry. This paper addresses this issue by reviewing key aspects relevant to process design to pave the way for future application. It will help to narrow down struvite process design options and thus reduce the voluminous calculations for a detailed analysis. Struvite process development, research trend, product application and process economics are reviewed and a conceptual process design is provided. This analysis provides comprehensive information that is essential for future industrial struvite crystallization process design.