This study investigated snail shell as a carrier to immobilize Pseudomonas putida and Bacillus subtilis isolated from refinery effluent for the degradation of naphthalene in synthetic wastewater at various process conditions such as initial naphthalene concentration, pH, adsorbent dosage and ambient temperature of 30 o C in batch mode. The results showed that the adsorption and the biodegradation capacity increased with increase in naphthalene concentration, where 73.11%, 74.46% and 65.20% of the optimum concentration (50 mg/L) were removed by immobilized Pseudomonas putida, Bacillus subtilis, and snail shell respectively after 72 hours incubation. The optimal degradation occurred at the adsorbent dosage of 2 g at pH 9 and pH 7 for the adsorption and biodegradation respectively. The results were well fitted to both Langmuir and Freundlich models. Therefore, snail shell can be employed as a low-cost adsorbent and solid support matrix for immobilizing microorganisms in remediating hydrocarbon contaminants.

The treatment of pollution using eco-friendly and sustainable methods is one of the bases of biotechnology. The work reports the use of periwinkle snail shell (PS) as carrier to immobilize Pseudomonas macerans and Bacillus subtilis for the biodegradation of 1-methyl naphthalene in aqueous medium. The biodegradation of 1-methyl naphthalene (500 mg L-1) were monitored after 36 h and 72 h by determining the concentration of carbonic acid (by titrimetric method) following the release of carbon (IV) oxide. The pH as well as the Fourier Transform-infrared (FT-IR)of the metabolites from the bioreactors/reactors were also studied. The pH of all the supernatants in the bioreactors/reactors decreased with time. There was increase in the concentration of H2CO3 due to the biodegradation of 1-methyl naphthalene by immobilized Pseudomonas macerans and Bacillus subtilis on 1.0 g and 2.0 g of PS. However, the use of immobilized Pseudomonas macerans on PS resulted to significant biodegradation of 1-methylnaphthalene (range of 0.61-0.81 mg/L H2CO3) compared to degradation alone with PS after 72 h. FTIR of the metabolite at end products show new peaks within 3372-3268 cm-1 and within 1643-1640cm-1 , these bands are attributed to overlapping of hydroxyl (OH) and carbonyl (C=O) stretching in carboxylic acid respectively, this implies that 1-methyl naphthalene got converted to carboxylic acid. Therefore, the use of carbonaceous wastes for localization in order to enhance biodegradation of hydrocarbons can be harnessed for mop-up of oil spills.

This work is aimed at assessing the effect of incorporating Pseudomonas macerans and Bacillus subtilis on burnt kaolin (BK) during the biodegradation of 1-methyl naphthalene. The biodegradation was monitored by determining the concentration of CO2 released. Immobilized Pseudomonas macerans on BK released CO2 in the range of 0.72-0.83 mg/L, while this was 0.68-0.78 mg/L with Bacillus subtilis; for the degradation alone the range was 0.39-0.46 mg/L after 72 h. Generally, the concentration of carbon (IV) oxide released by the immobilized Pseudomonas macerans was more than that by Bacillus subtilis. Therefore, immobilization using BK resulted to better removal of the organic pollutant. The FTIR indicated presence of new peaks within the regions 3272-3265cm-1 and 1647-1640cm-1 attributed to overlapping of hydroxyl (-OH) and carbonyl (C=O) stretching in carboxylic acid. The absorptions within 1114-1088 cm-1 , and at 1408cm-1 are due to CO stretching and O-H in plane bending of carboxylic acid respectively. The use of kaolin for environmental clean-up of organic pollutants will enhance the value chain of solid minerals in Nigeria.