Recent advances in pretreatment of lignocellulosic wastes and production of value added products

This study highlights the recent advances in the treatment and value addition of lignocellulosic wastes (LCW) with main focus on domestic and agro-industrial residues. Mechanical, physical and biologicaltreatment systems are brought into perspective. The main value-added products from lignocellulosic wastes are summarized in a manner that pinpoints the most recent trends and the future directions. Physicochemical and biological treatment systems seem to be the most favored options while biofuels, biodegradable composites and biosorbents production paints a bright picture of the current and futurebio-based products. Engineered microbes seem to tackle the problem of bioconversion of substrates that are otherwise non convertible by conventional wild strains. Although the main challenge facing LCW utilization is the high costs involved in treatment and production processes, some recent affordable processes with promising results have been proposed. Future trends are being directed to nanobiotechnology and genetic engineering for improved processes and products. The paper presents state of the art review of the dual advantage of handling LCW for cleaner environment and productionof renewable bio-products

Characteristics and dyes biodegradation potential of crude lignolytic enzymes from white-rot fungus crepidotus variabilis isolated in coastal Tanzania

Lignocellulosic enzymes from Crepidotus variabilis collected from mangrove forests of coastal Tanzania were investigated by using standard methods, and their ability to degrade aromatic compounds were elucidated. The fungal crude enzyme filtrates had maximum laccase (Lac), lignin peroxidase (LiP) and manganese peroxidase (MnP) activities of 70 U/mL, 16 U/mL and 8, U/mL respectively. The crude enzyme extracts were able to oxidize rhemazol brilliant blue-R (RBB-R) dye, phenol, "-naphthol and pyrogallol. Also, they could remove up to 58% and 92% color fromraw textile effluent and aromatic dyes, respectively, after 14 days of incubation at 30ºC and pH 4.5. Desalted and size-separated enzyme filtrates, resolved by sodium docecyl sulphatepolyacrylamide gel electrophoresis (SDS-PAGE) and isoelectric focusing (IEF), showed laccasesand peroxidases from C. variabilis to have molecular weights of 67 kDa and 47 kDa, respectively, while the isoelectric points (pI) of laccases and peroxidases were found to lie in a range of 3.0 to 4.1. The study provided basic information on the characteristics of crude lignolytic enzymes fromC. variabilis and confirmed it to be one of the potential biodegraders of aromatic compounds that could be applied in bioremediation of polluted ecosystem

Trends in industrial and environmental biotechnology research in Tanzania

This paper reviews the trends in industrial and environmental biotechnology research in Tanzania for the past 20 years. Researches on production of bio-energy, enzymes and organic acids are reviewed.Furthermore, researches related to wastewater treatment systems including water stabilization ponds and constructed wetlands are covered. Brief highlights are made on researches related tobioprospecting and molecular biology techniques used in identification of organisms. In critically reviewing the research done so far, an attempt is made to pinpoint significant research gaps in areassuch as single cell protein, biomining, biocomposting and bioengineering. This paper, therefore, provides an overview of the renewable raw materials available in the developing countries and outlines the researches that have been done to convert them to bio-products, while reducing bio-wastes. The identified gaps will serve as guidance to scientists who are interested in doing research in untapped areas of biotechnology

Influence of sampling depth and post-sampling analysis time on the occurrence of coliforms and vibrio in water and shellfish

The bacteriological quality was examined at the water surface, 3 m depth and in the shellfish flesh, and the results were compared to other potential pathogenic indicator organisms. The study was conducted at Long Harbour (mussel farm), St. John's and Outer Cove sites of Newfoundland, Canada. Bacteriological analysis was carried out for samples taken at water depth and at 1, 6, 12 and 24 hours post-sampling. It was observed that the total and faecal coliform bacteria were significantly higher in the 3 m water depth samples than in the surface water samples (ANOVA, F = 59.41, 26.751, 9.82 (T.C); 46.41, 26.81, 10.72 (F.C);

Monitoring of Heavy Metal Loading into the Wetlands South of Lake Victoria Basin, Nothern Tanzania

The paper discusses sources, concentrations and physicochemical parameters of heavy metals of environmental concern in the wetlands of Lake Victoria basin in Tanzania. The metals investigated include copper (Cu), lead (Pb), zinc (Zn), cadmium (Cd), chromium (Cr), nickel (Ni), arsenic (As), manganese (Mn), cobalt (Co) and mercury (Hg). These metals are released into the wetlands via weathering and erosion of rock formations, mining operations and industrial activities, discharge of municipal and domestic waste, and use of agrochemicals. The levels of these heavy metals in soil, sediment, water, and biota differ. Wetlands impacted by gold mining activities in the South Lake Victoria basin show elevated heavy metal contents in soil and sediment, particularly Cu (13-415 mg/kg), Pb (24-94 mg/kg), Zn (9-80 mg/kg), Cr (19-77 mg/kg), Ni (12-37 mg/kg) and Hg (0.19-1.76 mg/kg), contrary to non-impacted wetlands, which contain relatively low concentration of these metals (Cu 1-18 mg/kg, Pb 0-27 mg/kg, Zn 5-22 mg/kg; Cr 5-25 mg/kg, Ni 2-8 mg/kg, Hg <0.075 mg/kg). Elevated metal concentrations in soil and sediment are correlated with high metal contents in some plants within the affected wetlands. Oxidation and leaching of sulfide-bearing gold mine tailings resulted in acid mine drainage (AMD) with pH 3.25 - 4.10) and enhancement of heavy metal load and dissolved solids in streams draining into Nungwe Bay wetland on the southwestern shore of the Lake Victoria. Water samples from Bulyankhulu wetland drainage system were found to contain abnormally high Cu concentrations in the order of 270 mg/l. Samples from Mwakitolyo-Isanga and Nungwe Bay had higher values of Cr concentrations than those from Bulyankhulu and Luchili wetlands. Manganese was recorded to be 2.04 mg/L in a sample from Nungwe Bay, the reason being its mobilization from deeply weathered terrain associated with iron oxides.Keywords: Heavy metals; wetlands; Lake Victoria gold field; mining

Combined chemical and biological treatment of recalcitrant industrial effluents: a case study on kraft pulp wastewater.

The chemical degradation of lignin-rich kraft pulp wastewater was carried out by ozonation process flowed by biological treatment using activated sludge. The effects of pH on the degradation of lignin and the production of organic acids were examined experimentally in the ozonolysis of wastewater. The strong alkaline condition enhanced not only the degradation of lignin but also the production of organic acids. The maximum value of BOD5/COD obtained after 12 hours of ozonation was 0.41, indicating that ozone treatment improved the biodegradability of the kraft pulp wastewater. The dynamic behaviours of microbial growth and substrate consumption were investigated in the biodegradation of organic acids using activated sludge. Maleic acid and oxalic acid in the ozonized wastewater were degraded completely by the activated sludge in shake-flasks and bench-scale aerated bioreactor experiments. The immobilized activated sludge culture using polyurethane foam (PUF) was most effective in degrading organic acids in continuous culture condition at an optimum hydraulic retention time (HRT) of 14 hours. The study confirmed that consecutive treatments by ozone and activated sludge are effective methods to treat industrial effluents containing recalcitrant environmental pollutants such as kraft pulp wastewater. Tanzania Journal of Science Volume 27A (Special Issue) 2001, pp. 79-9