Volume 3 Issue 6
Authors: García K.; Pérez M.
Abstract: This paper presents the study of co-digestion of two types of organic wastes: cattle manure and sewage sludge from waste water treatment stations. Co-digestion of sewage sludge and cattle manure has the advantage of sharing processing facilities, unifying management methodologies, reducing operating costs and dampening investment and temporal variations in composition and production of each waste separately. The aim of this work was to select suitable operating conditions (both composition and temperature) of anaerobic co-digestion process of cattle manure and sewage sludge to optimize the process in the biogas generation. The batch tests have been developed at mesophilic and thermophilic conditions to determine the anaerobic biodegradability of three different mixtures of cattle manure and sewage sludge, both in static or stirring conditions. The obtained experimental results indicate that the anaerobic biodegradability of raw sludge and cattle manure mixtures is more efficient at thermophilic conditions since a greater elimination of organic matter with a greater methane yield is obtained. The most efficient process corresponds to the mixture with 25% v/v of cattle manure and 75% v/v of raw sludge with values of 62% and 75.7% of COD and DOC removals, respectively and methane yields of 2200 mL CH4/g CODr and 306 ml CH4/gVSr, presenting a period of starting of 12 days. Also, it is verified that a higher amount of cattle manure in the mixture means a higher alkalinity and a greater percentage of methane in biogas. The biodegradability validation tests at stirring conditions confirm the kindness of the thermophilic process.
Keywords: Co-Digestion; Biodegradability; Cattle Manure; Sewage Sludge; Mesophilic; Thermophilic
Authors: Nisarg Patel; Louis Hemple; Ralph Tripp
Abstract: Children seem to be particularly vulnerable to harmful effects of ambient pollution due to higher inhalation ratio than adults as well as due to their lungs not having a fully developed defense system against ambient pollution. Increased prevalence of respiratory track symptoms, allergen sensitization, worsening of asthma, and increased use of anti-asthma medications has been linked to high ambient air pollution episodes. Lung growth and development has also been shown to be impaired in children due to high exposures. The harmful effects of ambient pollution can be seen in fetuses from the exposures of their mothers. A study has even linked neonatal morbidity to the concentration of pollutants in the atmosphere.
Keywords: Ambient Air Pollution; Children; Health; Development
Authors: S. M. Azam; A. A. Shaikh; Z. M. Shareefdeen
Abstract: In this study, the effect of oxygen on the removal of toluene is demonstrated using a biofilter packed with peat media. Experimental results obtained from the peat-biofilter are validated with numerical predictions from an earlier model. There is an acceptable agreement between them. The increase in the level of oxygen increased the removal of toluene; however, the effect was not significant at inlet concentration of 1.5 gm-3. A correlation between removal efficiency of toluene and fraction of oxygen in the inlet airstream is developed. The simulation data showed that at high toluene concentrations, the effect of oxygen was more significant. Although this study is of industrial significance, the results are valid for hydrophobic compounds (i.e., toluene). It is expected that for hydrophilic compounds (i.e., ethanol) the effect of oxygen in the inlet air on biofilter performance will be more prominent.
Keywords: Oxygen Limitation; Toluene Biofiltration; Peat Biofilter; Model Predictions; Experimental Validation
Authors: Vinayak K. Patki; S. Shrihari; B Manu
Abstract: A study was conducted to assess water quality in the various zones of municipal distribution system for Solapur city (India) using water quality index technique. The variation in the water quality parameters was found to be pH (6.25-9.25), Total Alkalinity (88-408),Hardness (144-432),DO (1.48-9.8),Total solids (304.3-1011) and MPN (0-21).The WQI in various zones of distribution system for Solapur city varies temporally and spatially. The variation in WQI was found to be from 25.4 to 98. Such large variation in WQI was due to more variation in DO, TS and MPN. The TS and MPN exceeds the ICMR tolerance limits in many zones. It was observed that main cause of deterioration in water quality is due to regrowth of microorganisms in the distribution system and overhead tanks, non replacement of old pipes, corrosion of pipe material and reduction in the water treatment efficiency at water works against the population growth. The study reveals that out of twenty nine zones in the study area, for zones two, four, twenty three and twenty nine water quality was found to be critical and pose a serious threat to public health.
Keywords: Water Quality Index; Municipal Distribution System; Twenty Nine Zones
Authors: K.O. Moseti; T. Kinyanjui; J.K. Wanyoko; J.C. Too; F.N. Wachira; K.G. Omondi; J.K. Kurgat
Abstract: Accurate quantitation of levels of essential and non-essential elements in tea is of great importance as they are directly related to health and disease. In this study, levels of Iron (Fe), Zinc (Zn), Copper (Cu), lead (Pb) and Cadmium (Cd) in tea grown and marketed in Kenya were quantified by Flame Atomic Absorption Spectroscopy (FAAS). In unprocessed tea, the levels were found to range between 54.6 and 123.3 μg/g for Fe, 15.4 and 37.5 μg/g for Zn, 10.3 and 14.8 μg/g for Cu, 0.12 and 0.28 μg/g for Pb and 10.0 and 27.1 μg/kg for Cd whereas in black tea, the levels ranged between 81 and 369 μg/g for Fe, 17.1 and 44.9 μg/g for Zn, 9.0 and 17.8 μg/g for Cu, 0.12 and 0.41 μg/g for Pb and 9.1 and 40.0 μg/kg for Cd. The general accumulation pattern of these elements was established to be Fe > Zn > Cu > Pb > Cd in both unprocessed and black tea. All tea samples had metal contents within the Maximum Permissible Concentrations (MPC) set for tea, hence safe for consumption.
Keywords: Essential Elements; Non-Essential Elements; FAAS; Black Tea