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Analysis of solids in natural waters
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The presence of toxic organic and inorganic substances in rivers and oceanic sediments is in part due to man-made pollution. Their monitoring by chemical analysis of oceanic, estuarine, and river sediments or of organisms living in the respective ecosystems are of utmost importance. The purpose of this book is to provide the chemist with all available information for the rapid development and proper carrying out of these methods of analysis. Crompton's book is the first book which covers all kinds of samples including living organisms.
Contamination of sediments is found not only in rivers but also in estuarine sediments and sometimes in oceanic sediments, and this sediment analysis provides a means of tracking elements from their sources through the ecosystem. Another consideration is that fish, particularly bottom feeding fish in rivers and oceans, pick up contaminants when sediments enter their gills and the contamination of fish by toxic substances has definite toxicological implications in the case of fish that are eaten both by man and, in the case of fish-meal, by animals. The analysis of fish samples is therefore of great importance and is dealt with fully here. Crustacea which, by their nature are bottom feeding, also pick up toxic substances from water and sediments, and, moreover, have the characteristic of concentrating such substances in their tissues at levels much higher than those occurring in their surroundings. Whereas analysis of water samples provides a spot check on the concentration of a particular substance at one point in time, analysis of crustacea provides, with much greater sensitivity, an integrated concentration level over a considerable time span. This is highlighted by the mussel watch program instigated in the USA wherein samples of living mussels are taken regularly at specified points around the coast and analyzed for metals and organics. Such studies provide vital information on whether contaminant levels are increasing or decreasing and it is expected, for example, that lead levels in mussels will soon start to fall dramatically as a result of the introduction of lead-free petroleum. Much the same can be said for the analysis of algae.
Wastewater treatment : biological and chemical processes
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Wastewater flows are not steady or uniform, but vary from one hour to another, from day to day, from month to month and from year to year. When building a treatment plant, it is important to know the volumes of wastewater and their variations, now as well as in future. Based on the knowledge of the wastewater, the design of the treatment plant can be determined, taking into account the wastewater to be treated. In this connection measurements are useful; if such measurements do not exist, an estimate should be made. In respect of the volume of future wastewater, the development should of course be taken into account, i.e. a prognosis should be made.
Measurements of the volume of wastewater will be either in the form of curves or in the form of figures (metering). Fig 1.1 shows a diurnal variation for wastewater in the influent entering a treatment plant. The curve is the sum of domestic, industrial and public institution wastewater, infiltration and ex-filtration. There is no reason to consider the size of the individual contributions as the curve shows what reaches the treatment plant. In case of a projection of the volumes of wastewater and their variations, however, it is recommended to analyze the curve and the catchment area for the purpose of splitting up the sub-contributions as it will be easier to project these separately This is briefly dealt with in Sections 1.2 a By processing the data statistically a more detailed picture of wastewater variations is obtained. The different volumes of water (volume, maximum hour, maximum second, etc. over a 24-hour period) will often be normally distributed or log-normally distributed. Data sets for wastewater are never ideal as there will be irregularities which may, if they are too excessive, result in a special treatment of the data.
Fractile diagrams can be an important tool in the design of treatment plants. Fig 1.2 gives an example of such a diagram. The 60 per cent fractile is frequently used as an average load and a fractile of 85-90 per cent as a maximum load.
Analysis of solids in natural waters
- Auteur
- Crompton, Thomas R.
- Sujet
- Traitement ; Analyse ; Eaux
- Cote
- 628.11 CRO
- Date_TXT
- Berlin : Springer , 1996
- Type de document
- Livre
Wastewater treatment : biological and chemical processes
- Auteur
- Mogens, Henze
- Sujet
- Traitement ; Analyse ; Eaux
- Cote
- 628.162 HEN
- Date_TXT
- New york : Springer , 1997
- Type de document
- Livre
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