SOURCE:

Faculty: Physical Sciences
Department: Pure And Industrial Chemistry

CONTRIBUTORS:

Nwosu, U. Lovelyn,
Ajiwe V.I.E.
Okoye P.A.C.

ABSTRACT:

This study was carried out to evaluate the concentrations of heavy metals and other contaminants in the effluents from some food industries in Anambra State. Effluents from Life Breweries, Onitsha; KP beverages, Ogidi; Obisco beverages, Ogidi; Golden Vegetable Oil, Onitsha and Resource Improvement and Manufacturing Company (RIMCO Nnewi) in Anambra State were sampled for a period of eight months – four months rainy season and four months dry season – for comparison; and analyzed for levels of heavy metals pollution using Atomic Absorption Spectrophotometer (AAS). Physico-chemical parameters, microbiological and organic pollutants loads of the effluents were also determined using standard analytical methods. Results obtained were compared with the Federal Ministry of Environment Industrial Effluent Limit (FMEnv) to determine the level of conformity of these industries with this standard. Result of the mean concentrations of the heavy metals were generally above the allowable industrial effluent limit. It was discovered that the total mean level of the heavy metals were higher in the dry season than in the rainy season in almost all the food industries studied. The mean concentrations of mercury in the dry season were in the decreasing order of 3.783 + 0.860mg/l (Savana) > 3.182 + 0.497mg/l (Obisco) > 2.865 + 0.497mg/l (Golden) > 2.724 + 0.497mg/l (KP) > 2.655 + 0.497mg/l (Life) > 0.878 + 0.497mg/l (RIMCO) respectively compared to the rainy season levels of 1.985 + 0.860mg/l (Savana) > 1.935 + 0.497mg/l (Golden) > 1.874 + 0.497mg/l (Obisco) > 1.638 + 0.497mg/l (Life) > 1.564 + 0.497mg/l (RIMCO) > 1.252 + 0.497mg/l (KP) respectively. Two sample paired t – test showed that there were no significant difference (P > 0.05) in the levels of Pb, Cr, As, Cd, and Zn in both seasons except for Hg and Fe which were significantly higher (P < 0.05) in the dry season than in the rainy season in all the effluent samples. Analysis of Variance (ANOVA) showed that there were no significant difference (P > 0.05) in the mean concentrations of Hg, Fe, Pb, Cr, Cd, and Zn among the effluent samples except arsenic levels which showed significant difference (P < 0.05) among the different effluents studied. Apart from pH and hardness levels (which failed to meet the FMEnv effluent limit), other physico-chemical parameters of the effluents were either within or below the allowable industrial effluent limit. Again, two sample paired t-test showed that pH, TS, TDS and TSS were highly significant (P < 0.05) between rainy and dry seasons. Though pH and TSS were higher in the dry season than in the rainy season, TS and TDS were higher in the rainy season. Nevertheless, Analysis of Variance (ANOVA) indicated that there were significant difference (P < 0.05) in the mean concentrations of pH, TS and TDS among the different samples but TSS was not significant. Alkalinity, hardness, chloride and nitrate levels were not significant (P > 0.05) between rainy and dry season though there was significant difference (P < 0.05) in the levels of chloride and nitrates among the different industries studied. The most probable number (MPN/100ml) index of organisms were highest in the effluents from Golden oil in the dry season (35MPN/100ml) followed by Savana (33MPN/100ml) in the rainy season, though these were below the 500MPN/100ml recommended by FMENV, in industrial effluents. Organisms isolated were Enterobacter aerogens, Bacillus cereus, and Escherichia coli. Organic pollutants indentified in the effluents were mainly toluene compounds, 3, 5 – di – ter – butylphenol, hexa decanoic acid, Di – n – octylphthalate and 2 – methylnaphthalene among others. The pollution index values for mercury, zinc, lead, iron, arsenic, chromium and cadium showed significant degree of pollution by these heavy metals. Pollution potential of the effluents studied ranged in the order: Savana effluent > Life breweries effluent > Obisco effluent > Golden effluent > KP effluent > RIMCO effluent respectively.