Ricardo Bello-Mendoza

Use of spent substrate after Pleurotus pulmonarius cultivation for the treatment of chlorothalonil containing wastewater.

Lignocellulosic materials are used as substrate for the cultivation of the edible mushroom Pleurotus pulmonarius. After two or three flushes of mushrooms, the spent substrate is discarded although it still has an important enzymatic activity that can be used for several purposes. In this study, we sought to determine the technical feasibility of using spent substrate from P. pulmonarius to degrade chlorothalonil. Reaction mixture was prepared with 6 ml of pesticide aqueous solution (2 mg active ingredient/l) and 3 ml of enzymatic extract obtained from spent P. pulmonarius substrate. The enzymatic reaction (27 °C, pH 7.4) was conducted for 1 h with sampling at 15 min intervals. The effect of storage time and temperature (freezing or refrigerating) of spent substrate and enzymatic extract, respectively, on the activity over chlorothalonil was determined. Freshly obtained spent substrate extract was able to reduce 100% of the initial concentration of chlorothalonil (2 mg/l) after 45 min of reaction. Storage time had a negative effect on the stability of the enzymatic activity: with spent substrate stored for a week, chlorothalonil concentration was reduced in 49.5% after 1 h reaction and with substrate stored for two and three weeks, the degradation efficiency decreased to 9.15% and 0%, respectively. Cooling and freezing the spent substrate extract also had a negative effect on chlorothalonil degradation.

Shearing of biofilms enables selective layer based microbial sampling and analysis

Granules are large, self‐supporting biofilms that form naturally in high‐rate anaerobic treatment systems and are extremely important to reactor functionality. Granules exhibit functional and phylogenetic layering, interesting to both scientists and technologists. Until now, it has only been possible to analyze layering through sectioning and microscopic analysis with fluorescent in situ hybridization, or to analyze the whole granule through DNA extraction and microbial community profiling methods. This means different functional and spatial layers cannot be analyzed separately, including next generation sequencing techniques, such as pyrotag sequencing. In this work, we describe a method to remove microbes selectively from successive spatial layers through hydraulic shearing and demonstrate its application on anaerobic granules of three different types (VFA‐, carbohydrate‐, protein‐fed) in size ranges 0.6–2 mm. Outer layers in particular could be selectively sheared as confirmed by FISH. TRFLP was used as an example bulk DNA method on selectively sheared fractions. A shift in dominant population was found from presumptive acidogens (such as Bacteroidetes and Anaerolinea) in outer layers to syntrophs (such as Syntrophomonas and Geobacter) in inner layers, with progressive changes through the depth. The strength of the shear‐bulk molecular method over FISH was that a deeper phylogenetic profile could be obtained, even with TRFLP, and that prior knowledge of the community is not required. Biotechnol. Bioeng. 2013;110: 2600–2605.

Removal of Chlorothalonil, Methyl Parathion and Methamidophos from Water by the Fenton Reaction

The efficiency of a dark Fenton system (H2O2/Fe2+) to remove chlorothalonil from water, alone and in the presence of the organophosphorous pesticides methyl parathion and methamidophos, was evaluated. Here we show that the process is rapid and efficient. Nearly complete degradation of chlorothalonil and methyl parathion (98%) was observed in less than 10 min whereas methamidophos showed similar levels of efficiency only after 40 to 90 min. Formulating agents did not appear to impair the degradation of active ingredients. Interactions during the degradation of mixtures of the three pesticides only appeared to affect methamidophos degradation.

TRATAMIENTO DE AGUA RESIDUAL DOMÉSTICA MEDIANTE UN REACTOR RAFA Y UNA CELDA MICROBIANA DE COMBUSTIBLE

The performance of a system consisting of an up-flow anaerobic sludge blanket (UASB) reactor and a microbial fuel cell (MFC) for the treatment of low-strength wastewater and the recovery of energy was evaluated. The UASB reactor (1 L) was continuously fed with raw domestic wastewater under hydraulic retention times (HRT) of 12 and 6 h. The MFC (250 mL) was operated in batch mode and fed with either raw wastewater (HRT = 12 h) or the effluent from the UASB reactor (HRT = 6 h). It was found that the removal of organic matter by the coupled UASB–MFC system (88 % chemical

Use of solid phosphorus fractionation data to evaluate phosphorus release from waste activated sludge

Waste activated sludge (WAS) can become an important source of phosphorus (P). P speciation was examined under anaerobic conditions, with different pH (4, 6 and 8) and temperatures (10, 20 and 35 °C). Aqueous P was measured and an extraction protocol was used to find three solid phosphorus fractions. A pH of 4 and a temperature of 35 °C gave a maximum of 51% of total P solubilized in 22 days with 50% of total P solubilized in 7 days. Batch tests indicate that little pH depression is needed to release non-apatite inorganic P (including microbial polyphosphate), while a pH of 4 rather than 6 will release more apatite inorganic P, and that organic P is relatively more difficult to release from WAS. Fractionation analysis of P in WAS can aid in design of more efficient methods for P recovery from WAS.

Degradation of anti-inflammatory drugs in municipal wastewater by heterogeneous photocatalysis and electro-Fenton process

ABSTRACT Non-steroidal anti-inflammatory drugs (NSAID) are compounds frequently found in municipal wastewater and their degradation by conventional wastewater treatment plants (WWTP) is generally incomplete. This study compared the efficiency of two advanced oxidation processes (AOP), namely heterogeneous photocatalysis (HP) and electro-Fenton (EF), in the degradation of a mixture of common NSAID (diclofenac, ibuprofen and naproxen) dissolved in either deionized water or effluent from a WWTP. Both processes were effective in degrading the NSAID mixture and the trend of degradation was as follows, diclofenac > naproxen > ibuprofen. EF with a current density of 40 mA cm−2 and 0.3 mmol Fe2+ L−1 was the most efficient process to mineralize the organic compounds, achieving up to 92% TOC removal in deionized water and 90% in the WWTP effluent after 3 h of reaction. HP with 1.4 g TiO2 L−1 at pH 7 under sunlight, produced 85% TOC removal in deionized water and 39% in WWTP effluent also after 3 h treatment. The lower TOC removal efficiency shown by HP with the WWTP effluent was attributed mainly to the scavenging of reactive species by background organic matter in the wastewater. On the contrary, inorganic ions in the wastewater may produce oxidazing species during the EF process, which contributes to a higher degradation efficiency. EF is a promising option for the treatment of anti-inflammatory pharmaceuticals in municipal WWTP at competitive electrical energy efficiencies.

Photo-assisted electrochemical degradation of polychlorinated biphenyls with boron-doped diamond electrodes

ABSTRACT The capacity of the photo electro-Fenton (PEF) process to degrade a mixture of seven polychlorinated biphenyl (PCB) congeners was studied. Boron-doped diamond (BDD) sheets were used as anode and cathode in the experimental electrolytic cell that contained Na2SO4 0.05 M at pH 3 as supporting electrolyte for the electro generation of H2O2 at the cathode. The effects of UV light intensity (254 and 365 nm), current density (8, 16 and 24 mA cm−2) and ferrous ion dosage (0.1, 0.2 and 0.3 mM) on PCB (C0 = 50 μg L−1) degradation were evaluated. The highest level of PCB degradation (97%) was achieved with 16 mA cm−2 of current density, 0.1 mM of ferrous ion and UV light at 365 nm as irradiation source after 6 h of reaction. PCB28, PCB52 and PCB101 were not detected after 0.5, 1.5 and 3 h of reaction, respectively. The degradation of PCB138, PCB153, PCB180 and PCB209 was also high (>95%). The PEF system outperformed other oxidation processes (electro-Fenton, anodic oxidation, Fenton, photo-Fenton and UV photolysis) in terms of reaction rate and degradation efficiency. These results demonstrate for the first time the degradation of PCB209, the most highly chlorinated PCB congener, by an advanced electrochemical oxidation process.

Water quality of the Grijalva river in the Chiapas and Tabasco border

El objetivo fue caracterizar la calidad de agua en una seccion del rio Grijalva y en algunos de sus afluentes en la frontera entre los estados de Chiapas y Tabasco, en la epoca de lluvias y secas