Bioutilization of spent mushroom compost for remediation of heavy metal rich effluents
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Date
2020
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Punjab Agricultural University, Ludhiana
Abstract
The present study was conducted to use spent mushroom compost (SMC) as a low cost
effective biosorbent combining the advantage of biosorption and bioaccumulation approach
for remediation of heavy metal rich effluents. Effluent samples were collected from two
Common Effluent Treatment Plants (CETPs) located at Ludhiana (L-CETP) and Jalandhar (JCETP).
Samples were analysed for various physico-chemical parameters, whereby DO (43.92
mg/l) and BOD values (13.2 mg/l) were low in L-CETP whereas COD value (320 mg/l) was
higher than permissible limit (250 mg/l) indicating that sample was polluted with organic
contaminants. In J-CETP, DO (92.0 mg/l) and BOD (71.5 mg/l) values were high while COD
value was low (240 mg/l) indicating that sample has indigenous microflora. Total solids (TS)
and Total dissolved solids (TDS) were found to be high in J-CETP. Metal profile of effluent
samples was estimated using Inductively Coupled Argon Plasma-Atomic Emission
Spectroscopy (ICAP-AES). In Ludhiana CETP, Cr was dominant heavy metal with a
concentration of 226.62 ppm, followed by Ni 28.12 ppm and Pb 0.77 ppm. In Jalandhar
CETP, the concentration of Cr was 1.83 ppm, followed by Pb 0.39 ppm and Ni 0.10 ppm.
Heavy metal tolerance was determined by growing cultures of Pleurotus florida, Agaricus
bisporus, Volvariella volvacea and Calocybe indica in Potato Dextrose Agar (PDA) plates
amended with heavy metals. Cultures of white rot fungi were most sensitive to Hg and least
sensitive to Cr. Among the four selected strains, Volvariella volvacea was found to be highly
resistant to Cr with 22.5% inhibition of growth at 250 ppm. SMC of selected white rot fungi
was dried, grinded and analysed for various physico-chemical parameters whereby low values
of cellulose, hemicellulose and lignin indicated their degradation during the process of
composting and mushroom growth. Batch experiments were carried out in erlenmeyer flasks
to study the effect of various parameters like pH, temperature and initial metal concentration
on biosorption. Maximum removal of Cr was obtained at Ci-50 mg/l, pH-4-6 and
temperature-25°C. Experimental results were well fitted to Langmuir isotherm than to
Freundlich isotherm. These standardized conditions were used to study metal uptake from
effluent samples by SMC packed in a bioreactor. Maximum removal of Cr was achieved with
contact time of 2 hrs with A. bisporus SMC, 3hrs for P. florida SMC and 1.5 hrs for C. indica
SMC. FT-IR spectrum analysis of SMC showed shift in peaks at 2918 cm-1 to 2980 cm-1 due
to stretching of CH and CH2 group, 1744.7 cm-1 to 1739.6 cm-1 because of masking of
protonated carboxyl group and peak at 1500 cm-1 showed the presence of lignin group in
treated and untreated spent compost.