Production of a resilient biosurfactant using agro-wastes and Paenibacillus dendritiformis isolated from petroleum-contaminated soil: a break-even analysis at pilot scale

Abstract

Wastes from mustard oil mills and dairy were used as partial replacement of pure reagents in modified Bushnell and Haas broth media for production of biosurfactant by Paenibacillus dendritiformis isolated from petroleum-contaminated soil. The process was optimised by construction of a response model using Taguchi experimental design, leading to a 28.23% increase in performance characteristics and a 13.23 % increase in yield of biosurfactant. The optimized production medium consisted of carbon @7.9 %, nitrogen @ 1.1% and agitation rate 180 r.p.m. This was provided by adding glucose @ 2%, ammonium nitrate @0.2%, mustard oil seed meal @10% and whey@ 10% in modified Bushnell Haas broth. The biosurfactant produced retained its properties during exposure to a wide range of pH values (5-11), high temperatures (up to 121C), high salinities of up to 5% and also five -fold concentration. Approximately three- fold increase in yield of the biosurfactant (25g/L to 68.5g/L) was obtained upon scaling-up the production from 100ml to 1500 ml in a lab scale fermenter with agitation @ 150r.p.m. and D.O. levels maintained at 6mg/L. Power calculations and the cost thereof was calculated (Rs 10.24 /L) and summed up with the cost of raw materials Rs 8.40/L and found to be Rs 18.64/L of product .Since 68.5g product is present in 1L, the cost is calculated to be Rs 271/- per kg. Comparison with selling price of currently used chemical surfactants like Linear Alkyl Benzene sulphonic acid (LAB) and sodium Lauryl sulphate and Sodium Lauryl ether sulphate (SLS and SLES) reveals that prices of these products varies from Rs 120 to 600 per kg depending on manufacturer and quality, order quantity. From the above studies it can be seen that production and use of this multiutility biosurfactant has, besides a clear advantage over chemically produced surfactants in terms of sustainability, a fairly good comparison with selling price of currently used chemical surfactants. The present study on the production costs (excluding capital costs) successfully demonstrates a break even analysis into the production of biosurfactants.