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Table 1 Physico-chemical characteristics of palm oil effluents to which Heteroclarias were exposed for 28 days

From: Haemato-biochemical and ionic regulatory responses of the hybrid catfish, Heteroclarias, to sublethal concentrations of palm oil mill effluents

  Value Local regulatory limit International regulatory limit
NSDWQ (2005) NIS (2007) NESREA (2011) TDIW (1997) USEPA (2011) WHO (2011)
Physico-chemical parameter
Temperature (°C) 36.58 ± 7.90 30–32 N/A N/A N/A   30–32
pH 5.78 ± 0.32 6.50–8.50 6.50–9.50 6.00–9.00 5.00–9.00 6.50–8.50 6.50–8.50
EC (µS/cm) 823.25 ± 70.31 N/A 1000 N/A N/A N/A 1,000
TDS (mg/l) 2,036.02 ± 186.23 500 500 500 N/A 500 < 1000
BOD (mg/l) 256.90 ± 26.50 N/A N/A 50 < 100 250 N/A
COD (mg/l) 1.992.04 ± 71.18 N/A N/A 90 < 1000 410 N/A
Total alkalinity (mg/l) 512.76 ± 31.44 N/A NA 150 N/A 20 N/A
Nitrates (NO3 mg/l) 68.23 ± 7.81 N/A 50 10 N/A 10 50
Sulphate (SO42 mg/l) 169.20 ± 16.43 N/A 100 N/A N/A N/A 500
Chloride (mg/l) 626.09 ± 23.10 > 1.50 250 N/A N/A 250 N/A
Metal content (mg/l)
Copper (Cu) 1.42 ± 0.22 N/A 1000 0.5 N/A 1.3 2000
Cadmium (Cd) 0.91 ± 0.03 N/A 0.003 0.2 N/A 0.01 0.003
Chromium (Cr) 0.68 ± 0.21 N/A    N/A   
Iron (Fe) 0.39 ± 0.01 N/A 0.300 N/A N/A 0.3 N/A
Lead (Pb) 0.18 ± 0.02 0.01 0.01 0.05 N/A 0.02 0.01
Zinc (Zn) 4.03 ± 0.05 N/A 3000   N/A 5 N/A
  1. EC electrical conductivity, TDS total dissolved solids, BOD biological oxygen demand, COD chemical oxygen demand, NSDWQ Nigeria Standard drinking water quality, NIS Nigeria Industrial Standard, NESREA National Environmental Standard Regulation Enforcement Agency, TDIW Thai Department of Industrial Works, USEPA United States Environmental Protection Agency, WHO World Health Organization, N/A not available