Development of a novel fungal consortium for the treatment of molasses distillery wastewater

Treatment of NSAPs-rich petrochemical wastewaters using a two-stage combined process of fungi and activated sludge

A two-stage biological process using fungi and bacteria was set-up and tested for treating a petrochemical wastewater containing naphthalene sulphonic acid polymers. The fungal treatment was carried out through a trickling filter inoculated with Pleurotus ostreatus attached on Luffa cylindrica acting as both physical support and carbon source. The fungal reactor was operated in non-sterile conditions setting two pH values (5 and 6) and two hydraulic retention times (2 d and 3 d). The effluent was then sent to an activated sludge reactor operating the second stage of the treatment. Using an HPLC-based technique, it was observed that the fungal reactor was capable of reducing the polymerization grade of naphthalene sulphonic acid polymers up to 35%, thus increasing significantly the biodegradability of the petrochemical wastewater, from the initial 9% to 46%. The two-stage process allowed to remove about 50% of the total COD much higher than 9% that can be achieved with activated sludge alone. The use of Luffa cylindrica as support for fungi allowed to limit bacterial contamination of the trickling filter and enhanced enzymatic production (on average 20 U/L of Laccase) without any release of non-biodegradable by-products in the effluent. Extraction and PCR-amplification of fungal DNA was carried out along with over 70 d running process in order to monitor the changes of the fungal community inside the reactors. Results showed that Meyerozyma, Fusarium and Thricoderma, spp. developed inside the reactor with Thricoderma, spp. representing the main constituent of fungal biomass at the end of the experiment.

The role of cosubstrate and mixing on fungal biofilm efficiency in the removal of tannins

Tannins are polyphenolic compounds produced by plants and they are used in industrial vegetable tanning of leather. Tannins represent one of the low biodegradability substances in tannery wastewaters with high recalcitrant soluble chemical oxygen demand, furthermore high concentration of tannins can inhibit biological treatment. In the present study, four novel rotating submerged packed bed reactors were inoculated with a selected fungal strain to reach a biological degradation of tannins in non-sterile conditions. The selected fungal strain, Aspergillus tubingensis MUT 990, was immobilised in polyurethane foam cubes carriers and inserted inside a submerged rotating cage reactors. The reactors were feed with a solution composed of four tannins: Quebracho (Schinopsis spp.), Wattle (Mimosa spp.), Chestnut (Castanea spp.) and Tara (Caesalpinia spp.). Four reactors with a volume of 4 L each were used, the co-substrate was pure malt extract, the hydraulic retention time was 24 h and the pH setpoint was 5.5. The reactors configuration was chosen to allow the study of the effect of rotation and the co-substrate addition on tannins removal. The experiment lasted two months and it was achieved 80% of chemical oxygen demand and up to 90% dissolved organic carbon removal, furthermore it was detected an important tannase activity.

A preliminary report of indigenous fungal isolates from contaminated municipal solid waste site in India

Municipal solid waste (MSW) containing harmful substances is a major concern in waste management and can cause adverse effects on diversity of fungi in soil. The main objective was to evaluate the fungal diversity inhabiting in the soil nearby MSW disposal site. The fungal strains were isolated in potato dextrose agar (PDA), media at temperatures 28 ± 1 °C by using standard serial dilution pour plate method, and appeared fungal colonies identified based on morphological characteristics. The overall most fungal diversity was found in soil sample collected from S5, followed by S4, S3, S1, and least in S2 site. A total of 24 fungal isolates recovered from the different MSW sites and Aspergillus sp., Fusarium sp., and Curvularia sp. genus has isolated from all the samples. In addition, the metal tolerance index performed because it needs to classify the fungus for their best use as potential agent for environmental protection. The metal tolerance outcomes revealed that both metals (cadmium and chromium) has appeared as the highest growth inhibitor for most strains and even fungal colonies did not propagate very well on the surface of media. Therefore, these findings suggest that the pre-adapted indigenous fungal isolates have proven remarkable tolerance ability to both metals. Furthermore, these highly metal-tolerant fungal strains are recommended for detail research or can use in pilot-scale bioremediation application to treat contaminated site.

Comparison of ITS and 18S rDNA for estimating fungal diversity using PCR-DGGE

Both the internal transcribed spacer (ITS) region and 18S rRNA genes are broadly applied in molecular fingerprinting studies of fungi. However, the differences in those two ribosomal RNA regions are still largely unknown. In the current study, three sets of most suitable subunit ribosomes in ITS and 18S rRNA were compared using denaturing gradient gel electrophoresis (DGGE) under the optimum experimental conditions. Ten samples from both aquatic and soil environments were tested. The results revealed that the ITS region produced range-weighted richness in the range 36-361, which was significantly higher than that produced by 18S rDNA. There was a similar tendency in terms of the Shannon-Weaver diversity index and community dynamics in both water and soil samples. Samples from water and soil were better separated using ITS than 18S rDNA in principal component analysis of DGGE bands. Our study suggests that the ITS region is more precise and has more potential than 18S rRNA genes in fungal community analysis.

Optimization of three-stage Anammox system removing nitrogen from landfill leachate

Advanced nitrogen removal had been realized from mature landfill leachate via three-stage anaerobic ammonium oxidation (Anammox) system during the previous study. However, the Anammox system was influenced by factors such as influent nitrite and organic concentrations and needed to be optimized. To optimize the Anammox system, this study investigated Anammox Sequence Batch Reactor (ASBR) with different feeding modes and influent organic concentrations. The results showed that with influent ammonia and nitrite concentrations of 250±20 and 320±20mg/L, respectively, a continuous feeding mode reduced the adverse effect of high influent nitrite concentration on Anammox. A small amount of organics improved rather than inhibited nitrogen removal. However, as influent COD increased (from 600±50 to 800±50mg/L), Anammox was gradually inhibited. Influent organics concentration should be kept below 800mg/L, which facilitated Anammox.

Characterization and application of bioflocculant prepared by Rhodococcus erythropolis using sludge and livestock wastewater as cheap culture media

A new bioflocculant was produced by culturing Rhodococcus erythropolis in a cheap medium. When culture pH was 7.0, inoculum size was 2 % (v/v), Na2HPO4 concentration was 0.5 g L(-1), and the ratio of sludge/livestock wastewater was 7:1 (v/v), a maximum flocculating rate of 87.6 % could be achieved. Among 13 different kinds of pretreatments for sludge, the optimal one was the thermal-alkaline pretreatment. Different from a bioflocculant produced in a standard medium, this bioflocculant was effective over a wide pH range from 2 to 12 with flocculating rates higher than 98 %. Approximately, 1.6 g L(-1) of crude bioflocculant could be harvested using cold ethanol for extraction. This bioflocculant showed color removal rates up to 80 % when applied to direct and disperse dye solutions, but only 23.0 % for reactive dye solutions. Infrared spectrum showed that the bioflocculant contained functional groups such as -OH, -NH2, and -CONH2. Components in the bioflocculant consisted of 91.2 % of polysaccharides, 7.6 % of proteins, and 1.2 % of DNA. When the bioflocculant and copper sulfate (CuSO4) were used together for decolorization in actual dye wastewater, the optimum decolorization conditions were specified by the response surface methodology as pH 11, bioflocculant dosage of 40 mg/L, and CuSO4 80 mg/L, under which a decolorization rate of 93.9 % could be reached.

Lindane degradation by Candida VITJzN04, a newly isolated yeast strain from contaminated soil: kinetic study, enzyme analysis and biodegradation pathway

A new yeast strain was isolated from sugarcane cultivation field which was able to utilize lindane as sole carbon source for growth in mineral medium. The yeast was identified and named as Candida sp. VITJzN04 based on a polyphasic approach using morphological, biochemical and 18S rDNA, D1/D2 and ITS sequence analysis. The isolated yeast strain efficiently degraded 600 mg L⁻¹ of lindane within 6 days in mineral medium under the optimal conditions (pH 7; temperature 30 °C and inoculum dosage 0.06 g L⁻¹) with the least half-life of 1.17 days and degradation constant of 0.588 per day. Lindane degradation was tested with various kinetic models and results revealed that the reaction could be described best by first-order and pseudo first-order models. In addition, involvement of the enzymes viz. dechlorinase, dehalogenase, dichlorohydroquinone reductive dechlorinase, lignin peroxidase and manganese peroxidase was noted during lindane degradation. Addition of H2O2 in the mineral medium showed 32 % enhancement of lindane degradation within 3 days. Based on the metabolites identified by GC-MS and FTIR analysis, sequential process of lindane degradation by Candida VITJzN04 was proposed. To the best of our knowledge, this is the first report of isolation and characterization of lindane-degrading Candida sp. and elucidation of enzyme systems during the degradation process.

Purification and biochemical characterization of a new alkali-stable laccase from Trametes sp. isolated in Tunisia: role of the enzyme in olive mill waste water treatment

A white-rot basidiomycete, isolated from decayed acacia wood (from Northwest of Tunisia) and identified as Trametes sp, was selected in a broad plate screening because of its ability to decolorize and dephenolize olive oil mill wastewater (OMW) efficiently. The major laccase was purified and characterized as a monomeric protein with apparent molecular mass of 61 kDa (SDS-PAGE). It exhibits high enzyme activity over broad pH and temperature ranges with optimum activity at pH 4.0 and a temperature of 60 °C. The purified laccase is stable at alkaline pH values. The enzyme retained 50 % of its activity after 90 min of incubation at 55 °C. Using ABTS, this laccase presented K m and V max values of 0.05 mM and 212.73 μmoL min(-1) mg(-1), respectively. It has shown a degrading activity towards a variety of phenolic compounds. The purified laccase was partially inhibited by Fe(2+), Zn(2+), Cd(2+) and Mn(2+), while Cu(2+) acted as inducer. EDTA (10 mM) and NaN3 (10 mM) were found to completely inhibit its activity. 73 % OMW was dephenolized after 315 min incubation at 30 °C with 2 U mL(-1) of laccase and 2 mM HBT.