Anaerobic/aerobic treatment of selected azo dyes in wastewater

Journal Article · Sat Jan 01 04:00:00 EST 1994 · Waste Management; (United States)

DOI:https://doi.org/10.1016/0956-053X(94)90005-1· OSTI ID:7082497

Seshadri, S; Bishop, P L ^[1]; Agha, A M ^[2]

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1. Univ. of Cincinnati, OH (United States). Dept. of Civil and Environmental Engineering
2. Univ. of Aleppo (Syrian Arab Republic). Faculty of Civil Engineering

Azo dyes represent the largest class of dyes in use today. Current environmental concern with these dyes revolves around the potential carcinogenic health risk presented by these dyes or their intermediate biodegradation products when exposed to microflora in the human digestive tract. These dyes may build up in the environment, since many wastewater treatment plants allow these dyes to pass through the system virtually untreated. The initial step in the degradation of these dyes is the cleavage of the Azo bond. This cleavage is often impossible under aerobic conditions, but has been readily demonstrated under anaerobic conditions. The focus of the study was to determine the feasibility of using an anaerobic fluidized-bed reactor to accomplish this cleavage. The effects of typical process variables such as hydraulic retention time (HRT), influent dye concentration levels, and degree of bed fluidization on removal efficiencies were also studied. The four dyes selected for this study were Acid-Orange 7, Acid-Orange 8, Acid-Orange 10, and Acid-Red 14. The effectiveness of using a bench-scale-activated sludge reactor as a sequenced second stage was also examined. Results indicate that nearly complete cleavage of the Azo bond is easily accomplished for each of the four dyes under hydraulic retention times of either 12 or 24 h. Initial results indicate, though, that aromatic amine by-products remain. The sequenced second stage was able to remove the remaining Chemical Oxygen Demand (COD) load to acceptable levels. Work is presently underway to determine the face of the anaerobic by-products in the aerobic second stage.

• OSTI ID: 7082497
• Journal Information: Waste Management; (United States), Journal Name: Waste Management; (United States) Vol. 14:2; ISSN WAMAE2; ISSN 0956-053X
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
540320* -- Environment
Aquatic-- Chemicals Monitoring & Transport-- (1990-)
AZO COMPOUNDS
AZO DYES
BIODEGRADATION
CHEMICAL EFFLUENTS
CHEMICAL REACTIONS
CHEMICAL WASTES
DECOMPOSITION
DYES
FLUIDIZED BEDS
HYDROGEN COMPOUNDS
INDUSTRIAL WASTES
LIQUID WASTES
MANAGEMENT
NONRADIOACTIVE WASTES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXYGEN COMPOUNDS
POLLUTION
PROCESSING
WASTE MANAGEMENT
WASTE PROCESSING
WASTE WATER
WASTES
WATER
WATER POLLUTION