A SINDH government report states that the Latifabad water treatment plant failed because of inappropriate technology, high turbidity, inadequate skilled manpower, the choking of filter media owing to high level of turbidity, the deterioration of the pipe network, and improper security. The report recommended the establishment of rapid-sand filters system.

High raw water turbidity (greater than 10 ntu - nephelometric turbidity unit) will create problems for rapid-sand filters as well, by frequently clogging the filter beds and producing turbid water, if filter beds are not frequently cleaned — and they never will, considering the attitude of Hyderabad’s civic authorities.

The rational solution is to have roughing filters, ahead of the main plant. Roughing filters are, typically, either a large compartment filled with successive layers of filter media decreasing in size in the direction of flow; or multiple compartments connected in series, each filled with one media size. Water flow through the filter can be either horizontally or vertically. Roughing filters come in three configurations: a horizontal roughing filter, a down flow roughing filter in series, and an up flow roughing filter in series.

It is suggested that slow-sand filtration system should be used, if sufficient land is available. Rapid-sand filtration system requires highly-trained and educated operators.

A senior citizen
Hyderabad

Published in Dawn, September 19th, 2018