Advanced oxidation process H2O2/UV combined with anaerobic digestion to remove chlorinated organics from bleached kraft pulp mill wastewater

This study investigated the application of an advanced oxidation process combining hydrogen peroxide with ultraviolet radiation (H2O2/UV) to remove recalcitrant compounds from Kraft bleaching effluent. Anaerobic pre-treatment was performed to remove easily degraded organics using a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. Bleaching plant effluent was treated in the HAIB reactor processed over 19 h of hydraulic retention time (HRT), reaching the expected removal efficiencies for COD (61 +/- 3%), TOC (69 +/- 9%), BOD5 (90 +/- 5%) and AOX (55 +/- 14%). However, the anaerobic treatment did not achieve acceptable removal of UV254 compounds. Furthermore, there was an increase of lignin, measured as total phenols. The H2O2/UV post-treatment provided a wide range of removal efficiencies depending on the dosage of hydrogen peroxide and UV irradiation: COD ranged from 0 to 11%, UV254 from 16 to 35%, lignin from 0 to 29% and AOX from 23 to 54%. All peroxide dosages applied in this work promoted an increase in the BOD5/COD ratio of the wastewater. The experiments demonstrate the technical feasibility of using H2O2/UV for post-treatment of bleaching effluents submitted to anaerobic pre-treatment.

Prey digestion in the midgut of the predatory bug Podisus nigrispinus (Hemiptera: Pentatomidae)

Pre-oral digestion is described as the liquefaction of the solid tissues of the prey by secretions of the predator. It is uncertain if pre-oral digestion means pre-oral dispersion of food or true digestion in the sense of the stepwise bond breaking of food polymers to release monomers to be absorbed. Collagenase is the only salivary proteinase, which activity is significant (10%) in relation to Podisus nigrispinus midgut activities. This suggests that pre-oral digestion in P. nigrispinus consists in prey tissue dispersion. This was confirmed by the finding of prey muscles fibers inside P. nigrispinus midguts. Soluble midgut hydrolases from P. nigrispinus were partially purified by ion-exchange chromatography, followed by gel filtration. Two cathepsin L-like proteinases (CAL1 and CAL2) were isolated with the properties: CAL1 (14.7 kDa, pH optimum (pHo) 5.5, km with carbobenzoxy-Phe-Arg-methylcoumarin, Z-FR-MCA, 32 mu M); CAL2 (17 kDa, pHo 5.5, km 11 mu M Z-FR-MCA). Only a single molecular species was found for the other enzymes with the following properties are: amylase (43 kDa, pHo 5.5, km 0.1% starch), aminopeptidase (125 kDa, pHo 5.5, km 0.11 mM L-Leucine-p-nitroanilide), alpha-glucosidase (90 kDa, pHo 5.0, km 5 mM with p-nitrophenyl alpha-D-glucoside). CAL molecular masses are probably underestimated due to interaction with the column. Taking into account the distribution of hydrolases along P. nigrispinus midguts, carbohydrate digestion takes place mainly at the anterior midgut, whereas protein digestion occurs mostly in middle and posterior midgut, as previously described in seed- sucker and blood-feeder hemipterans. (C) 2012 Elsevier Ltd. All rights reserved.

Digestion of feed fractions and intake of heifers fed hydrolyzed sugarcane stored for different periods

The objective of this study was to evaluate, in Nellore heifers, intake and digestibility of hydrolyzed sugarcane stored for different periods. The experimental design used was a 4 × 4 Latin square, four diets, four Nellore heifers with ruminal cannulas (initial body weight 285.4±23.08 kg and average initial age 14 months) and four periods of 21 days. The diets were composed by fresh sugarcane (time zero) or hydrolyzed sugarcane with addition of 0.5% of hydrated lime, stored for 24, 48 or 72 hours, as the unique forage. Intake and digestibility of feed fractions, nitrogen balance, microbial synthesis efficiency, total number of ruminal protozoans and ammoniacal nitrogen did not significantly change by storing sugarcane with addition of 0.5% of hydrated lime. Sugarcane pH varied quadratically for storage time, with maximum pH of 7.02 after 24 hours from lime addition. Ruminal liquid pH values were higher for heifers fed fresh sugarcane, in comparison with those fed hydrolyzed sugarcane. Sugarcane treated with 0.5% of hydrated lime stored for up to 72 hours does not change ruminal digestion to alter the amount of feed consumed by pubescent Nellore heifers. Thus, lime is a viable technology, once it allows long-duration storage and bee control on treated forage, which contributes to animal feeding logistics.