Most water analysts are using DPD kits and colorimeters to measure free chlorine residual, but there is a better way.

Photocatalysis is an advanced oxidation process aiming at the complete conversion of harmful and toxic dissolved contaminants in natural or drinking water into carbon dioxide, water and inorganics in presence of semiconducting materials such as TiO2 and ZnO, which act as catalysts.

Constructed wetlands (cws) for wastewater treatment may be part of the answer to the urgent need for a change in the approach to wastewater treatment in developing countries. Although thailand has several cws, there have been no studies of their sustainability. To remedy this, the sustainability of three promising cws in very different settings was assessed. These were located at koh phi phi, a world-renowned international tourist and holiday resort; sakon nakhon, a northeastern provincial capital; and ban pru teaw, a small post-tsunami village on the andaman coast.

Untreated waste water is a health hazard. Nonetheless, it should be considered a resource. Unless it is recycled and re-used, it will be impossible to provide all people in the cities of developing countries with safe drinking water. The example of India shows that agglomerations cannot get ever more fresh water from ever farther away.