Toxicity reduction of photo processing wastewaters

Abstract

The photo processing industry can be characterized by treatment processes and subsequent silver recovery. The effluents generated all contain various amounts of silver. The objectives of this study were to determine toxicity of photo processing effluents and to explore their toxicity mitigation. Six samples, from small shops to a major photo processing center, were studied. Two samples (I and VI) were found to be extremely toxic, causing 100 and 99% inhibition of duckweed frond reproduction, respectively, and were used for subsequent toxicity reduction experiments. Lime and sodium sulfide were effective for the toxicity reduction of Sample VI; both reduced its toxicity to negligible. Sample I was far more toxic and was first diluted to 2.2% and then treated with 0.5 g lime/100 mL, reducing toxicity from 100% to 12% inhibition.

Advanced oxidation of photographic processing effluents on novel heterogeneous fibrous catalyst

“…COD determination is based on the theoretical amount of oxygen required to oxidize organic compounds to CO 2 In the present study a stock standard solution of 1202 mg/L KHP which was equivalent to 2000 mg/L COD was prepared. The KHP concentration series equivalent to 2000, 1000, 750, 300 and 150 mg/L COD for calibration curve construction were prepared from the stock KHP standard solution.…”

“…2), which indicates an excess of residual H 2 O 2 . According to Talinli and Anderson [21], www.witpress.com, ISSN 1743-3541 (on-line) 2 2 to 1000 mg/L, the percent of COD removal (η) is then determined through S E = COD t -R p x 0.25 (2) where S E is the corrected value of COD after the reaction, COD t is the 'reading' value of COD after the reaction, R p is the residual amount of H 2 O 2 left in solution after the reaction.…”

“…Since photographic processing effluents have very high oxygen demand (COD value 90,000-150,000 mg O 2 /L), the use of chemical oxidation to reduce this is very attractive, particularly, the use of hydrogen peroxide as it is an ecologically friendly and pure product. Fenton's reagent (H 2 O 2 -Fe 2+ ) is extensively used in oxidation of photographic processing effluent [2,3,12] though other oxidative treatments, involving H 2 O 2 alone [13], H 2 O 2 and Fe powder (which is based on the homogeneous Fenton's reagent by dissolution of iron) [14], ClO - [15], and O 3 [11] are also used.…”

“…A number of organic and inorganic pollutants found in PPE, such as ammonium salts, ferrocyanide, thiocyanate, organic acids, aminophenols and phenylenediamines, are of special interest in waste treatment. Photographic processing effluents as water pollutants were of concern in the early 1970s, and ever since then, numerous studies have been undertaken in the treatment of PPE [1,2]. A number of methods have been investigated in order to treat PPE, such as reduction in COD by oxidation [2][3][4][5], UV radiation [6,7], biological treatment [8,9], incineration [10] and a combination of oxidation and UV radiation [11], with most of the published work in the patent literature.…”

“…Photographic processing effluents as water pollutants were of concern in the early 1970s, and ever since then, numerous studies have been undertaken in the treatment of PPE [1,2]. A number of methods have been investigated in order to treat PPE, such as reduction in COD by oxidation [2][3][4][5], UV radiation [6,7], biological treatment [8,9], incineration [10] and a combination of oxidation and UV radiation [11], with most of the published work in the patent literature. Since photographic processing effluents have very high oxygen demand (COD value 90,000-150,000 mg O 2 /L), the use of chemical oxidation to reduce this is very attractive, particularly, the use of hydrogen peroxide as it is an ecologically friendly and pure product.…”