Fernando Esparza-García

Toxicity assessment of soil amended with tannery sludge, trivalent chromium and hexavalent chromium, using wheat, oat and sorghum plants

This work assessed the effect of soil amended with tannery sludge (0, 500, 1000, 2000, 4000 and 8000 mg Cr kg(-1)soil), Cr(3+) as CrCl(3).6H(2)O (0, 100, 250, 500, 1000 and 2000 mg Cr kg(-1)soil), and Cr(6+) as K(2)Cr(2)O(7) (0, 25, 50, 100, 200 and 500 mg Cr kg(-1)soil) on wheat, oat and sorghum plants. Seed germination, seedling growth (root and shoot) and Cr accumulation in dry tissue were measured. Toxicological parameters; medium effective concentration, no observed adverse effect concentration and low observed adverse effect concentration were determined. Root growth was the most sensitive assessment of Cr toxicity (P<0.05). There was a significant correlation (P<0.0001) between Cr accumulation in dry tissue and toxic effects on seedling growth. The three Cr sources had different accumulation and mobility patterns; tannery sludge was less toxic for all three plant species, followed by CrCl(3).6H(2)O and K(2)Cr(2)O(7).

Biostimulation of micro-organisms from sugarcane bagasse pith for the removal of weathered hydrocarbon from soil

Aims:  In this study we studied the biostimulation of micro‐organisms associated with sugarcane bagasse pith for the removal of total petroleum hydrocarbon from a soil contaminated with weathered hydrocarbon.

Effect of combined nutrients on biosurfactant produced by Pseudomonas putida

Abstract This work investigated biosurfactant production by Pseudomonas putida in combined C/P, C/Ninorganic, C/Fe, C/Mg nutrient ratios and peptone concentration. Analysis of the 25−1 fractional factorial experimental design showed that only the C/Fe ratio had a significant (p < 0.02) effect on biosurfactant production. The highest amount of biosurfactant was obtained at low C/Fe ratios, but net surface tension did not show significant differences. In addition, low amounts of peptone and the C/P-C/Mg nutrient ratios interaction significantly (p < 0.05) enhanced the biomass produced by P. putida. Analysis of biosurfactant by gas chromatography (GC) showed that the hydrophilic fraction was composed by rhamnose and the hydrophobic fraction, mainly by palmitic (C16), stearic (C18:0), oleic (C18:1) and linoleic (C18:2) fatty acids.

Strictosidine-related enzymes involved in the alkaloid biosynthesis of Uncaria tomentosa root cultures grown under oxidative stress.

The activity and gene expression of strictosidine‐related enzymes in Uncaria tomentosa root cultures exposed to oxidative stress were studied. Elicitation with 0.2 mM hydrogen peroxide (H2O2) or a combination of 0.8 mM buthionine sulfoximine and 0.2 mM jasmonic acid (BSO‐JA) increased peroxidase activities by twofold at Day 8 and glutathione reductase by 1.4‐fold at Day 5 in H2O2 elicited cultures respect to the control. Production of monoterpenoid oxindole alkaloids (MOA), 3α‐dihydrocadambine, and dolichantoside was stimulated after H2O2 elicitation, reaching levels of 886.4 ± 23.6, 847.7 ± 25.4, and 87.5 ± 7.2 µg/g DW, at Day 8 which were 1.7‐, 2.1‐, and 2.3‐fold higher relative to control. BSO‐JA elicited cultures produced about twice alkaloids than H2O2‐treated cultures, following a biphasic pattern with maxima at 0.5 and 8 days. Alkaloid production was preceded by increase in strictosidine synthase (STR) and strictosidine glucosidase (SGD) activities. After elicitation with H2O2 or BSO‐JA, the STR activity (pKat/mg protein) increased by 1.9‐fold (93.8 ± 17.8 at 24 h) or 2.5‐fold (102.4 ± 2.2 at 6 h) and the SGD activity (pKat/mg protein) by 2.8‐fold (245.2 ± 14.4 at 6 h) or 4.2‐fold (421.2 ± 1.8 at 18 h) relative to control. STR and SGD transcripts were upregulated after elicitation. H2O2‐treated roots showed higher levels of STR at 48–192 h and SGD at 24–48 h, while BSO‐JA treatments showed STR increased at 12 h and SGD at 24 h. Also, LC/ESI‐MS confirmed the biosynthesis of dolichantoside from N‐ω‐methyltryptamine and secologanin by U. tomentosa protein extracts.

Upgrading of facultative waste stabilisation ponds under high organic load

Wastewater treatment using laboratory scale waste stabilisation ponds enriched with activated sludge was studied. After enrichment, the efficiency of these ponds under high organic loading rates (i.e., up to 2800kg CODha−1day−1) reached a maximum COD removal rate of 970kg CODha−1day−1, which is from 2 to 10 times more than commonly reported values, and suggests that enrichment is an effective method to improve stabilisation ponds.

Effects of Mixing Low Amounts of Orange Peel (Citrus reticulata) with Hydrocarbon-Contaminated Soil in Solid Culture to Promote Remediation

The effect of mixing low amounts of orange peel (Citrus reticulata) with a soil contaminated with hydrocarbons (58,000 mg kg−1 soil) for promoting the soil remediation in solid culture was studied. The experimental design was established in solid culture at soil/orange (Citrus reticulata) peel ratios of 100:0, 98:2, 96:4, 94:6 and 92:8, at 30% humidity and a C:N:P ratio of 100:10:1, for 15, 60 and 90 days, respectively. The total petroleum hydrocarbons (TPHs) decreased significantly (69%) after 15 days in the treatment with a soil to orange peel ratio of 92:8. Furthermore, in this treatment bacterial counts increased from 17 to 20 ln CFU (2.6 × 106 to 5 × 108), while the fungal count was 11 ln CFU (6.5 × 104) at initial and final time of treatment. An increase in microbial respiration activity and TPH removal (69%) was observed at other soil/orange peel ratios after 60 days when moisture content and nutrients were adjusted; however, N and P were not consumed at a great extent.

Phenol removal in upgraded facultative waste stabilisation ponds

Abstract Treatment of wastewater containing phenol, using laboratory scale waste stabilisation ponds enriched with activated sludge was studied. After enrichment, the efficiency of these ponds under high phenol loading rates (i.e. up to 408 kg phenol ha−1 day−1) was studied. At phenol loading rates of 6, 52, 312, 636 and 972 kg COD ha−1 day−1, the phenol removal efficiencies were 77, 69, 76, 59 and 52%, respectively. The results suggest that enrichment is an effective potential method to increase the removal capability of facultative ponds, not only for easily biodegradable compounds but also for xenobiotics

Fenton (H2O2/Fe) reaction involved in Penicillium sp. culture for DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane)] degradation

The purpose of this work was to demonstrate that a Fenton (H2O2/Fe) reaction was involved in DDT [1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane)] degradation in a culture of Penicillium sp. spiked with FeSO4. A commercial DDT mixture (10% DDE [1,1-dichloro-2,2-bis(p-chlorophenyl)ethylene], 30% o,p-DDT and 60% of p,p′ -DDT) of 10 mg L− 1 was used. Hydrogen peroxide (H2O2), tartaric acid and oxalic acid were identified at 18 h in culture media, with and without added DDT; this correlated positively with lowering of pH from 5.8 to 2.7. Lower concentrations of oxalic acid and H2O2 (7.9 and 52.6 mg L− 1, respectively) occurred in media with DDT at 30 h, in comparison to that one without DDT mixture (27.9 and 65.3 mg L− 1, respectively), at this time there was maximum degradation (87.7, 91.7 and 94.2%) for DDE, o,p-DDT and p,p′-DDT, respectively. We propose that the degradation of the DDT mixture by Penicillium sp. was through a Fenton reaction (H2O2/Fe) under acidic conditions produced in situ during the fungal culture amended with FeSO4.

Removal of phenanthrene in aqueous solution containing photon competitors by TiO2–C–Ag film supported on fiberglass

ABSTRACT Surface interactions with pollutants and photons are key factors that affect the applications of TiO2 in environmental remediation. In this study, the solubilizing agents dimethylsulfoxide and polyoxyethylene sorbitan monooleate, which act as photon competitors, had no effect on the photocatalytic activity of TiO2–C–Ag film in phenanthrene (PHE) removal. Fiberglass with TiO2–C–Ag coating removed 91.1 ± 5.2 and 99.7 ± 0.4% of PHE in treatments using UVA (365–465 nm) and UVC (254 nm) irradiation, respectively. The use of fiberglass as a support increased the superficial area, thus allowing PHE sorption. C and Ag, which are electrically active impurities in TiO2, enhanced its photocatalytic activity and thus the attraction of the pollutant to its surface. The use of high-frequency UV light (UVC) decreased the amount of carbon species deposited on the TiO2CAg film surface. X-ray photoelectron spectroscopy of the TiO2–C–Ag film revealed extensive oxidation of the carbon deposited on the film under UVC light and loss of electrons from Ag clusters by conversion of Ag0 to Ag3+.

Production of a halotolerant biofilm from green coffee beans immobilized on loofah fiber (Luffa cylindrica) and its effect on phenanthrene degradation in seawater

ABSTRACT A biofilm developed from low quality green coffee beans was tested for its capacity to degrade the polynuclear aromatic hydrocarbon (PAH), phenanthrene (Phe), in seawater. Microorganisms were immobilized on two types of Luffa cylindrica (with three and four placental cavities), and the effects of moisture content (20, 30 and 40% of water holding capacity) and particle size (<0.42 mm, 0.42–0.86 mm and 0.86–2.0 mm) of green coffee beans on microbial activity were considered. Biofilm growth determined by respirometry showed a highest microbial activity at a moisture content of 40% and particle size of 0.42–0.86 mm. The loofah fiber with three placental cavities showed the highest adherence of microorganisms. The kinetics of microbial growth in both seawater and distilled water and the scanning electron microscopies indicated that the microorganisms associated with green coffee beans are halotolerant. In fact, I-GCB-SW-G biofilm degraded 67.56% of Phe (50 mg L−1) in seawater, at a significantly higher rate than in distilled water (I-GCB-DW-W).