Bio-Remediation Of Cu, Ni And Cr From Rotogravure Wastewater Using Immobilized, Dead, And Live Biomass Of Indigenous Thermophilic Bacillus Species.

摘要

Heavy metals resistant thermophilic bacilli were isolated from Ma’een hot springs in Jordan and used as immobilized, dead and live biomass for bioremediation of heavy metals present in the wastewater effluent of Jordan Rotogravure Establishment (JRE). Four species of bacillus were isolated and identified. They include: Bacillus sphaericus, Bacillus pumilus, Panibacillus alvae and Geobacillus sterothermophilus. They all exhibit resistance to at least 100 mg/L Cupper (Cu), nickel (Ni), and chromium (Cr). A significant difference in Cu (p= 0.001), Ni (p= 0.013) and Cr (p= 0.035) mean biosorption capacity was recorded between Bacillus species. Heavy metals were reduced more efficiently with immobilized cells (p? 0.05). B. sphaericus have the highest ability to adsorb Cu (87.5%) and Ni (72.8%) present in rotogravure effluents in comparison to B. pumilus, Panibacillus alvae and G.sterothermophilus that showed 81%, 65.4% and 79.6% for Cu and 62.4%, 59% and 65.6% for Ni, respectively. A maximum removing efficiency was recorded for Cr by B. pumilus (86.5%) in comparison to 83%, 78.3% and 82.7% estimated for B. sphaericus, Panibacillus alvae and G. sterothermophilus respectively. Although the overall sorption efficiency doesn’t vary significantly within the temperature range 37°C- 70°C, thermophilic bacilli exhibit a maximum metal binding capacity at temperatures 60°C and 70°C. The affinity of Bacillus for heavy metals adsorption was found to be; Cu> Cr> Ni for B. sphaericus and Cr> Cu> Ni for other Bacillus species. Introduction Many waste materials discharged to the environment. Most are degraded slowly by living organisms into smaller harmless molecules; however some not easily broken down and instead they accumulate to levels which could pose health hazards. The disposal of heavy metals is a consequence of industrial activities like, electroplating, painting, petrochemical, chemical manufacturing, and textile industries [1]. Toxic metals such as Ag, Cd, Cr, Cu, Hg, Ni and Zn, make their way into water bodies which can produce harmful effects on human health when they are taken up in amounts that cannot be processed by the organism [2]. As a result, many new technologies are required to mitigate heavy metal concentrations to environmentally accepted levels.Rotogravure effluents contain certain heavy metals like chromium and copper which are generated during chrome plating and preparing of the printing rolls [3]. Removal of heavy metals from industrial effluents has conventionally been accomplished mainly by precipitation, ion exchange, and electrolytic technologies [4]. Physicochemical methods which have been used widely are expensive and ineffective, especially when the concentration of the polluted metals is below 50 mg/L [5]. Besides that, they have disadvantages like incomplete metal removal, energy requirements and generation of toxic sludge’s and other waste products that need to be disposal [6]. Various biomass materials and agricultural by-products have been utilized in the removal of toxic heavy metals from waste water [7, 8, 9]. However, bio-remediation of heavy metals by microorganisms may provide an attractive alternative to physico-chemical methods and has a great potential in industry [10, 11]. Microorganism's uptake metals either by bioaccumulation and /or biosorption [9, 12]. These processes use the functional groups present in bacterial, algal, and fungal cell wall to form complexes with metal ions and thereby aid in the removal of heavy metals. Metabolically active (living cells) and inactive (dead cells) were used in bioremoval process and behave in different ways. The former can only immobilize metals by biosorption, whereas the later may immobilize soluble metal species both by biosorption and by other mechanisms that are part of and/or are due to the microbial metabolism [13]. Researchers have been conducted in the area of mesophilic and certain thermophilic bacteria in the context of reduction, leaching and oth