CHROMIUM REMOVAL FROM CHELTECH (ZARIA) TANNERY EFFLUENT AS A FORM OF EFFLUENT TREATMENT
CHROMIUM REMOVAL FROM CHELTECH (ZARIA) TANNERY EFFLUENT AS A FORM OF EFFLUENT TREATMENT
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Date
2004-08
Authors
BUBA, MATTHEW ADAMU
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Abstract
Chrome is an indispensable input in chemical tanning of pelt. For
mass transfer reasons, not more than 80% of the chrome feed is absorbed by
the leather leaving a balance of over 20% in the effluent. This leads to
material loss if disposed untreated. In addition, the attendant possible
oxidation of chromium (III) to chromium (VI) (in the presence of manganese
(IV) oxide or under alkaline conditions) known for its carcinogenic effect,
makes it necessary to remove good part of the chrome from the effluent
before its disposal to sewers or surface water.
In this work, treatment CHELTECH (Zaria) tannery’s ‘mixed
effluent’ with varying amount of MgO (10 – 60 mg/l) at different contacting
times (15 – 120 minutes) reduced the concentration of chromium in the
effluent from 29.86 to 0.06 mg/l. This is equivalent to 99.8% chromium
removal. The 0.06 mg/l minimum chromium concentration value in the
treated effluent falls within the recommended limit for discharge into sewers
and surface waters.
Chromium recovered from the mixed effluent is known to produce
hard leather due to the presence of lime in the effluent. Therefore,
segregated spent chromium effluent was treated with varying amount of
MgO (50 – 900 mg/l) for 30 minutes. This was able to reduce the chromium
from 7020 to 982 mg/l, which is equivalent to 86% chromium removal. The
effect of varying contacting time (15 – 75 minutes) using 400 mg/l of MgO
reduced the amount of chromium in the effluent by 89.3%.
Treatment of the segregated spent chromium effluent offers an
effective recovery, as 6268.9 mg/l of chromium was removed as against
29.80 mg/l for mixed effluent using the same process.
Description
A THESIS PRESENTED TO THE POSTGRADUATE SCHOOL
AHMADU BELLO UNIVERSITY, ZARIA
IN PARTIAL FULFILLMENT OF THE REQUIREMENTS
FOR THE DEGREE OF MASTER OF SCIENCE IN
CHEMICAL ENGINEERING
DEPARTMENT OF CHEMICAL ENGINEERING,
AHMADU BELLO UNIVERSITY,
ZARIA.
Keywords
CHROMIUM REMOVAL,, CHELTECH,, TANNERY,, EFFLUENT,, EFFLUENT TREATMENT