Journal of the Association of Engineers, India

Dhrubajyoti Ghosh ¹, Rajat Mohan Chatterjee ¹

Affiliations
1 Calcutta Metropolitan Water and Sanitation Authority, IN

Abstract

The contribution of soil mechanics in designing the stress characteristics of the buried conduits subjected to superimposed load is unquestionable. The effective total load reaching the conduit buried under the depth of backfilled earth can only be computed with precise care to the behaviour of soil mass under stress. Without this knowledge, the designer remains incompetant to develop design methods or detect the failure if it might occur.

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Rajat Mohan Chatterjee ¹, Santimoy Niyogi ²

Affiliations
1 Calcutta Metropolitan Water and Sanitation Authority, IN
2 Civil Engineering, Jadavpur University, IN

Abstract

Activated sludge and its modifications, aerated lagoon and oxidation ditch methods of biological waste treatment require exogenous supply of air by means of aerators for furnishing the oxygen as needed for optimum aerobic metabolism. It is well established that the initial and subsequent costs of operation and maintenance of a sewage treatment plant as well as its performance are considerably influenced by the type of the aeration equipment used. Hence, extreme care and judgement must be exercised towards appropriate selection of aerator to satisfy the optimum requirements of the particular system for which it is being used. It must also be recognized that each type of aeration equipment has its individual features and is suited for a given set of conditions. The present paper summarises the salient features of the various types of aeration equipment available and provides guide lines for selection and design of aerators for wastewater treatment.

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