Agro-industrial Wastes For Production Research Articles

Hydraulic Conductivity of Compacted Tropical Clay Treated with Rice Husk Ash

Laboratory study on compacted tropical clay treated with up to 16% rice husk ash (RHA), an agro-industrial waste; to evaluate its hydraulic properties and hence its suitability in waste containment systems was carried out. Soil-RHA mixtures were compacted using standard Proctor, West African Standard and modified Proctor efforts at-2, 0, 2 and 4% of optimum moisture content (OMC). Compacted samples were permeated and the hydraulic behaviour of the material was examined considering the effects of moulding water content, water content relative to optimum, dry density and RHA contents. Results showed decreasing hydraulic conductivity with increasing moulding water content and compactive efforts; it also varied greatly between the dry and wet side of optimum decreasing towards the wet side. Hydraulic conductivity generally decreased with increased dry density for all effort. Hydraulic conductivity increased with rice husk ash treatment at the OMC; but were within recommended values of 1 x 10-7 cm/s for up to 8% rice husk ash treatment irrespective of the compactive effort used. This shows the suitability of the material as a hydraulic barrier in waste containment systems for up to 8% rice husk ash treatment and beneficial reuse of this agro-industrial waste product.

Response surface optimization of medium composition for protease production by Bacillus subtilis using cassava waste

Optimization of the growth condition for maximum growth rate and protease production was carried out using Bacillus subtilis. The optimization of protease production using agro industrial waste product such as cassava waste as substrate was performed with statistical methodology based on experimental designs. The screening of twelve nutrients for their influence on protease production was achieved using a Plackett-Burman design. MgSO4.7H2O, casein and glucose were selected based on their positive influence on protease production. The selected components were optimized using Response Surface Methodology (RSM). The optimum conditions are (% w/w): MgsO4.7H2O- 0.14, casein- 1.4 and glucose- 2.64. These conditions were validated experimentally which revealed an enhanced protease yield of 202.048 U/gds.

Production of alkaline protease by a thermophilic Bacillus subtilis under solid-state fermentation (SSF) condition using Imperata cylindrica grass and potato peel as low-cost medium: Characterization and application of enzyme in detergent formulation

Among the different agro-industrial waste products and kitchen waste materials, viz. mustered oil cake, wheat bran, rice bran, Imperata cylindrica grass, banana leaves, potato peels and used tea leaves screened as substrates/solid supports for the production of alkaline protease by a thermophilic strain of Bacillus subtilis DM-04 under solid-state fermentation, potato peel followed by I. cylindrica grass supported maximum protease production. Further, potato peel and I. cylindrica grass mixed in a ratio of 1:1 (w/w) significantly ( P < 0.05) enhanced the protease production by B. subtilis DM-04 compared to individual substrate. Among the tested nitrogen compounds, 0.1% (w/w) beef extract followed by yeast extract served as the best co-nitrogen sources for protease production by B. subtilis DM-04 strain on I. cyindrica grass. Distilled water adjusted to pH 8.0 was most efficient moistening agent for protease production. The crude protease displayed optimum activity at 37–45 °C temperature range and showed characteristics pH optima at pH 8.0–9.0. The protease from B. subtilis DM-04 retained 67% of its original activity post-heating at 60 °C for 15 min. Among the tested protein substrates, casein served as the most preferred substrate for the enzyme. Crude protease exhibited a significant stability and compatibility with most of the tested commercial laundry detergents, demonstrating its feasibility for inclusion in laundry detergent formulation.

Production and partial characterization of endoxylanase by Bacillus pumilus using agro industrial residues

Agro industrial residues, cheap sources of energy have high potential in the area of fermentation for the production of lignocellulases. Different agro industrial waste products were evaluated as substrates in submerged and solid-state fermentation for xylanolytic enzyme production by Bacillus pumilus and the enzyme titers were compared. Higher titer of endoxylanase was obtained with solid state than with liquid fermentation with feeble amount of cellulase. High proteolytic activity was observed in submerged fermentation where as in solid state the proteolytic activity was lower in all cases except in media supplemented with soy meal due to its high protein content. The endoxylanase produced by solid-state fermentation was stable over a wide range of pH and temperatures. The highest enzyme activity was obtained at pH 6.5–7 and at 50 °C. The enzyme could retain 30% of its activity even after 1 h at 60 °C. Considering the conditions under which Kraft pulps are bleached during the manufacture of paper, xylanase from B. pumilus exhibit favorable potential for application in the paper processing industries.

Simplex optimization of carotenoid production by Rhodotorula glutinis using hydrolyzed mung bean waste flour as substrate

The sequential simplex method was employed for the optimization of growth and carotenoid production in the yeast Rhodotorula glutinis using a substrate containing hydrolyzed mung bean waste flour from glass noodle production as the principal nitrogen source and sweet potato extract as the principal carbon source. Six experimental parameters were used: concentration of mung bean waste flour, concentration of sweet potato extract, pH, temperature, agitation rate and cultivation time. Under optimized conditions the cell dry weight was 10.35 ± 0.13 g/l and the total carotenoid content was 3.48 ± 0.02 mg/l using 23.63 g/l of H 2SO 4-hydroyzed mung bean waste flour, 51.76 g/l of sweet potato extract, pH 5.91, 30.3 °C, agitation rate of 258 rpm and incubation time of 94.78 h. These results for cell dry weight and carotenoid content were, respectively, 43 and 20% higher than could be obtained by varying one factor at a time. The present work demonstrates the effectiveness of using a widely available agro-industrial waste product as substrate and the efficiency of the sequential simplex optimization method in obtaining high yields.

Citrus waste recovery: a new environmentally friendly procedure to obtain animal feed

Citrus juice centrifugation pulp is the semi-solid product obtained from the industrial centrifugation of juices, to obtain a clear juice. This waste causes many economic and environmental problems because of its fermentability. In this paper we describe a method which makes it possible to obtain animal feed from citrus juice centrifugation pulp. To this end, alkaline and/or enzymatic treatments were carried out on the centrifugation pulp. These treatments facilitate pressing and so help to produce a material which, using suitable methods, may be dried. Enzyme treatment proved to be the most efficient of the methods under investigation designed to favour the pressing of the pulp. The product obtained with this method showed excellent digestibility in vitro and its protein content, although not especially high, compared favourably with that of many other agroindustrial waste products currently used as components of animal feed.

Microbial production of surfactants and their commercial potential.

Many microorganisms, especially bacteria, produce biosurfactants when grown on water-immiscible substrates. Biosurfactants are more effective, selective, environmentally friendly, and stable than many synthetic surfactants. Most common biosurfactants are glycolipids in which carbohydrates are attached to a long-chain aliphatic acid, while others, like lipopeptides, lipoproteins, and heteropolysaccharides, are more complex. Rapid and reliable methods for screening and selection of biosurfactant-producing microorganisms and evaluation of their activity have been developed. Genes involved in rhamnolipid synthesis (rhlAB) and regulation (rhlI and rhlR) in Pseudomonas aeruginosa are characterized, and expression of rhlAB in heterologous hosts is discussed. Genes for surfactin production (sfp, srfA, and comA) in Bacillus spp. are also characterized. Fermentative production of biosurfactants depends primarily on the microbial strain, source of carbon and nitrogen, pH, temperature, and concentration of oxygen and metal ions. Addition of water-immiscible substrates to media and nitrogen and iron limitations in the media result in an overproduction of some biosurfactants. Other important advances are the use of water-soluble substrates and agroindustrial wastes for production, development of continuous recovery processes, and production through biotransformation. Commercialization of biosurfactants in the cosmetic, food, health care, pulp- and paper-processing, coal, ceramic, and metal industries has been proposed. However, the most promising applications are cleaning of oil-contaminated tankers, oil spill management, transportation of heavy crude oil, enhanced oil recovery, recovery of crude oil from sludge, and bioremediation of sites contaminated with hydrocarbons, heavy metals, and other pollutants. Perspectives for future research and applications are also discussed.

Microbial production of surfactants and their commercial potential.

Many microorganisms, especially bacteria, produce biosurfactants when grown on water-immiscible substrates. Biosurfactants are more effective, selective, environmentally friendly, and stable than many synthetic surfactants. Most common biosurfactants are glycolipids in which carbohydrates are attached to a long-chain aliphatic acid, while others, like lipopeptides, lipoproteins, and heteropolysaccharides, are more complex. Rapid and reliable methods for screening and selection of biosurfactant-producing microorganisms and evaluation of their activity have been developed. Genes involved in rhamnolipid synthesis (rhlAB) and regulation (rhlI and rhlR) in Pseudomonas aeruginosa are characterized, and expression of rhlAB in heterologous hosts is discussed. Genes for surfactin production (sfp, srfA, and comA) in Bacillus spp. are also characterized. Fermentative production of biosurfactants depends primarily on the microbial strain, source of carbon and nitrogen, pH, temperature, and concentration of oxygen and metal ions. Addition of water-immiscible substrates to media and nitrogen and iron limitations in the media result in an overproduction of some biosurfactants. Other important advances are the use of water-soluble substrates and agroindustrial wastes for production, development of continuous recovery processes, and production through biotransformation. Commercialization of biosurfactants in the cosmetic, food, health care, pulp- and paper-processing, coal, ceramic, and metal industries has been proposed. However, the most promising applications are cleaning of oil-contaminated tankers, oil spill management, transportation of heavy crude oil, enhanced oil recovery, recovery of crude oil from sludge, and bioremediation of sites contaminated with hydrocarbons, heavy metals, and other pollutants. Perspectives for future research and applications are also discussed.

Evaluation of agro-industrial wastes as diets for culture of the fairy shrimpStreptocephalus proboscideus (Frauenfeld, 1873) (Crustacea:Branchiopoda:Anostraca)

Two micronized waste products were evaluated in a closed recirculation system for their suitability to replace a costly diet of live algae in the culture of the Sudanese fairy shrimp, Streptocephalus proboscideus. The test population was kept at a density of 50 individuals l−1 (sex ratio: 1/1). An agricultural waste product (YM20; mixture of pea and corn), and an industrial waste product (POME; Palm Oil Mill Effluent) were fed at two regimes: 0.1 and 0.2 mg DW animal−1 h−1. The microalga Selenastrum capricornutum, used as a reference diet at a density of 2.0±0.82 × 105 cells ml−1, proved adequate in preliminary screening experiments. The effect of the diets and feeding regimes on selected biological variables and water quality were followed by weekly observations and measurements. Results in terms of growth (= increase in length), cyst production, and mortality were more successful when animals were supplied high densities of YM20 than in all other treatments: mean brood size was 155±6 cysts with a maximum of 266. Length after 6 weeks was about 2 cm while this ranged between 1.4–1.7 cm for the other treatments. Weekly mortality rate was comparable under high food conditions. Mortality rate gradually increased from 5% in the first week to 15% in the last week. Water quality, especially nitrite concentration (measured as NO2-N), was slightly better in the dry food fed than in the algae fed cultures. Present results are promising for large-scale culturing of S. proboscideus in a cost-effective way by making use of agro-industrial waste products.