Coliforms removal in full-scale activated sludge plants in India.

This paper investigates the removal of coliforms in full-scale activated sludge plants (ASP) operating in northern regions of India. Log2.2 and log2.4 removal were observed for total coliforms (TC) and fecal coliforms (FC), respectively. However, the effluent still contained a significant number of TC and FC which was greater than the permissible limit for unrestricted irrigation as prescribed by WHO. The observations also suggest that extended aeration (EA) process operating under high mixed liquor suspended solids (MLSS) and sludge retention time (SRT) is more efficient in the removal of coliforms. Further attempts have been made to establish the relationship between two key wastewater parameters, i.e. biochemical oxygen demand (BOD) and suspended solids (SS) with respect to fecal and TC. The relationships were observed to be linear with a good coefficient of correlation. The interrelationship of BOD and SS with coliforms manifest that improvement of the microbiological quality of wastewater could be linked with the removal of SS. Therefore, SS can serve as a regulatory tool in lieu of an explicit coliforms standard.

Imidazoline and its derivatives: an overview.

Imidazoline derivatives, a class of novel cationic surfactants are presently gaining importance in global detergent market due to their wide range of applications. These are extensively used mainly as fabric softeners and antistatic agents. The present communication reviews the preparation, reaction scheme, reaction rates and properties of imidazoline derivatives. The analysis of imidazoline derivatives, its mode of action, their biodegradation and various applications have also been discussed.

Esterquats: the novel class of cationic fabric softeners.

Esterquats, which are quaternary ammonium compounds having two long (C(16)-C(18)) fatty acid chains with 2 weak ester linkages, represent a new generation of fabric softening agents, having replaced the dialkyldimethylammonium salts (e.g. DTDMAC and DSDMAC). The inclusion of ester linkages into the aliphatic chains has significantly improved the kinetics of biodegradation of the cationic surfactants, lowering the environmental exposure levels. This new generation of fabric softening agents combines a good environmental profile with the structural features required for an effective fabric conditioner. The present paper reviews the synthesis, types, actives combines a good environmental profile with the structural features required for a properties and applications of esterquats.

Laundry detergents: an overview.

Nowadays laundry detergents are becoming increasingly popular as they can be metered automatically into the washing machine, impart softness, antistaticness, resiliency to fabrics, mild to eyes and skins and shows good dispersibility in water. Because it is consumed when it is used, the sale of laundry detergent is a rather large business. There are many different kinds or brands of laundry detergent sold, many of them claiming some special qualities as selling points. A Laundry detergent composition is a formulated mixture of raw materials that can be classified into different types based on their properties and function in the final product. The different classes of raw materials are surfactants, builders, bleaching agents, enzymes, and minors which remove dirt, stain, and soil from surfaces or textiles gave them pleasant feel and odour. The physico-chemical properties of surfactants make them suitable for laundry purposes. Laundry detergent has traditionally been a powdered or granular solid, but the use of liquid laundry detergents has gradually increased over the years, and these days use of liquid detergent equals or even exceeds use of solid detergent. This review paper describes the history, composition, types, mechanism, consumption, environmental effects and consumption of laundry detergents.

Spatio-temporal variations in population growth in India since 1901.

"On the basis of census data we analyse population growth since 1901 first for India as a whole, secondly on State level. The spatio-temporal patterns suggest a process of innovation and diffusion with regard to the spatial change of natural increase. The southern States cover more stages of the model of demographic transition than the northern States. Explanations about these spatial differentials come for example [from] sociocultural differences between north and south determining two demographic regions according to Satpura Range." (SUMMARY IN GER AND RUS)

Calculation of water volume in step wells for cyclopicide application and its eco-epidemiological implication: mathematical validation of some theoretical considerations.

Chemical treatment of step wells to kill cyclopoid vectors of guinea worm by temephos (50 per cent E. C.) at the dose of 1 ppm is now an important activity of the guineaworm eradication programme in India. Calculation of correct volume of water in step wells, to determine the exact quantity of temephos to be applied, therefore, deserves adequate attention to prevent over and underdosing of stepwells by the chemical. The prescribed method of calculation of water volume includes two formulae; pi r2h and 1 x b x h (where h = mean depth for uneven bottoms and is a single depth measurement for almost even bottoms). Field observations revealed that in many stepwells there were marked variations in depth within the same well. These differences in depth ranged from small to very large in some wells. Since these depth variations would lead to miscalculation of water volume by existing method and the dose of temephos to be applied, with eco-epidemiological consequences, new formulae have therefore been deduced for conceivable patterns of depth variations by geometrical and algebric applications. The new formulae will permit calculation of, nearest to, exact quantity of temephos required for application. These formulae have been validated by an example.