AS reported, Sindh Public Health Engineering Department Secretary Tamizuddin Khero has said that the Umerkot and Jati filtration plants are functional, but due to a high level of turbidity and coliform bacteria, the water was not being supplied to consumers for drinking. Was the design of these two water treatment plants some kind of a joke?

All well-designed and properly-operated water treatment plants can handle variations in raw water turbidities and microbial loadings.

There is absolutely no question of well-designed plants to become inoperational, due to variations in turbidities and organic loadings.

Municipal water treatment plants in towns in developing countries are slow-sand filtration. They are robust, dependable, can withstand raw water quality variations, and more importantly, are most suitable for the turbid surface waters in Sindh.

This is a 100-year old established practice. Why is the PHED experimenting with reverse omissus (RO) or ultrafiltration (UF) systems?

The pore size of UF membranes is 0.002 to 0.1 microns (1 micron = 0.0001 millimeters). The pore size of RO membranes is 0.0001 to 0.001 microns. What will the UF system do, when the RO system has failed? If ultrafiltration fails (which is sure to happen), will the PHED opt for nanofiltration or microfiltration?

Karachi-based reputed civil engineering firms should be hired for the design and operation of water treatment plants in Sindh. The design should be vetted by a third party.

A water engineer

Hyderabad

Published in Dawn, February 10th, 2018