46    TREATMENT OF TANNERY WASTEWATER BY UPFLOW
ANAEROBIC SLUDGE BLANKET REACTOR
Anwar Khursheed, Research Associate
Rashid H. Siddiqi, Professor
Department of Civil Engineering
Aligarh Muslim University
U.P. India
INTRODUCTION
Kanpur city located on the banks of River Ganga is expected to generate 355 MLD municipal
wastewater by the year 2020. The 25 km stretch of the river along the city has been identified as the
most polluted reach due to discharge of untreated domestic and industrial wastes under a national
"Ganga Action Plan" of management of river water quality. The city has a cluster of about 150
tanneries on the south bank of the river discharging a total of 5.8 MLD wastewater. Under the action
plan it is proposed to intercept the waste from the tanneries by an industrial sewer and take it to a
common treatment facility where it may be mixed with 130 MLD municipal wastewater and treated
through a proposed conventional treatment plant or treated separately after suitable dilution by an
Upflow Anaerobic Sludge Blanket (UASB) reactor. The present paper describes laboratory studies
conducted to assess the anaerobic treatability of the waste using a bench scale 3.2 L reactor, which
paralleled the construction and operation of a 10 m3 UASB pilot plant.
TANNING PROCESS AND WASTEWATER CHARACTERISTICS
The tanneries at Kanpur process skins to finished or semifinished chrome and vegetable tanned
leathers. Some units process only semifinished leather to finished product. The flow from individual
units varies from 10 to more than 100 m3/d and 10 to 30 L/kg of hide processed depending upon the
capacity and process used.
An extensive survey was conducted in which discharges from each individual tannery were determined both in terms of quality and quantity. Based on this survey, a composite for the 150 tanneries
was prepared by mixing predetermined volumes of waste flows from specific operations of a larger
size tannery [Table I].'
The characteristics of the composite wastewater prepared according to Table I are given in Table
II.
MATERIALS AND METHODS
The laboratory UASB reactor set up is shown in Figure 1. It consisted of a transparent rigid plastic
pipe (85 mm i.d. x 630 mm length) with a settling funnel fitted at the top. The gas phase was
maintained at 175 mm water pressure by providing a water seal. The feed was pumped in at the
bottom of the tank using a peristaltic pump from a feed reservoir which was filled every day. Methane
gas was measured by displacement of a 5% NaOH carbon dioxide scrubbing solution in a Marriott
flask.
Wastewater composite sample was collected according to Table I and transported to the laboratory.
The feed was prepared by settling the waste for two hours and mixing the supernatant with local
domestic wastewater to obtain required dilutions.
The reactor was seeded with sludge obtained by settling raw municipal wastewater. Earlier studies
had indicated that the sludge obtained in this manner had adequate methanogenic activity. During the
start up the reactor was fed an acetate solution of 500 mg/L COD prepared in domestic wastewater at
24 h HRT for about 60 days. After this period when the COD of the reactor effluent had come down
to about 30 mg/L, the acetic acid was replaced by settled tannery waste.
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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