In a typical photocatalytic degradation experiment on acid violet dye, a certain amount of the catalyst (ZnO:AC) was added into 50 ml of the aqueous dye solution taken in a beaker. Then the beaker containing the dye solution was exposed to the light source, it should also be noted that no external supply of oxygen was employed. Dye samples of about 2 to 3 ml were taken out at a regular interval from the test solution, centrifuged for 4 to 5 min at 950–1000 rpm and their % transmittance was recorded at 540 nm using a visible spectrophotometer (Model: Minispec SL 171, Elico, India). Light source used for illumination in the photodegradation experiments was a UV tube (8W, Sankyo Denki, Japan), for comparison studies mercury vapor lamp (MVL, 300 W) and sunlight was used. The intensity of all the light sources was estimated by photolysis of uranil oxalate [12]. In case of textile effluent treatment, effluent from two different textile plants were collected and labeled as E1 and E2. The same photocatalytic experimental setup employed in the degradation of acid violet was employed. As-received effluent was used without any preliminary treatment, unless that the effluent was suitably diluted in order to facilitate the light penetration. The photodegradation path of the effluents was followed by the estimation of chemical oxygen demand (COD) and percentage transmission(%T)