Greetings from the ANU College of Engineering and Computer Science, where Dr K Srithar, visiting from Thiagarajar College of Engineering, Madurai, Tamil Nadu, India, is speaking on "Industrial effluent treatment using solar energy". He preceded the talk with some photos of the Meenakshi Amman Temple ( மீனாட்சி அம்மன் கோவில்).
Tanning leather create large quantities of effluent which is traditionally treated by drying in open ponds. These take large amounts of land. Dr. Srithar experimented with running a thin sheet of water over an inclined dark solar plate collector and a spray system. A combination of these were three to four times as effective as ponds for evaporation and used less than half as much land. There was a cost as pumps were needed. The spray system also had the advantage that it would continue to work at night.
Dr. Srithar then discussed how to increase the efficiency of solar stills, to produce fresh water from salty. These use a shallow pond of brackish water with a sheet of glass over it. He found that including sponges, sand, rocks or a roughened surface increased efficiency. The efficiency could be further increased by pre-heating the water in a solar pond, before introducing it to the solar still.