Ultraviolet light emitting diodes and hydrogen peroxide in the photodegradation of aqueous phenol

The novel system of ultraviolet (UV) light emitting diodes (LED) and hydrogen peroxide (H(2)O(2)) was studied for the degradation of phenol as a model organic pollutant in water. The effect of different viewing angles (15 and 120 degrees ), wavelengths (255, 265 and 280 nm) and phenol and H(2)O(2) concentrations were investigated in four photolytic batch reactors. Phenol degradation was observed to be most efficient with UV LEDs emitting at wavelength 280 nm, presumably due to the highest optical power. However, quantum yield for 280 nm reactor was only 0.23 compared to 0.33 of 255 nm reactor. Quantum yields for the rest of the reactors were 0.24 (265 nm, 120 degrees ) and 0.22 (265 nm, 15 degrees ). UV LEDs in combination with hydrogen peroxide are promising in wastewater treatment in degrading organic compounds, though development of both LEDs and reactor design is needed.     

Effect of pre-treatments on hydrolysis and methane production potentials of by-products from meat-processing industry

Language issues are problems with communication via speech, signs, gestures or their written equivalents. They may result from poor reading and writing skills, a mix of foreign languages and other circumstances. Language issues are not picked up as a safety risk on the shop floor by current safety management systems. These safety risks need to be identified, acknowledged, quantified and prioritised in order to allow risk reducing measures to be taken. This study investigates the nature of language issues related danger in literature, by experiment and by a survey among the Seveso II companies in the Netherlands. Based on human error frequencies, and on the contents of accident investigation reports, the risks associated with language issues were ranked. Accident investigation method causal factor categories were found not to be sufficiently representative for the type and magnitude of these risks. Readability of safety related documents used by the companies was investigated and found to be poor in many cases. Interviews among regulators and a survey among Seveso II companies were used to identify the gap between the language issue related dangers found in literature and current best practices. This study demonstrates by means of triangulation with different investigative methods that language issue related risks are indeed underestimated. A recommended coarse of action in order to arrive at appropriate measures is presented.     

Nitrate Reduction of the Siilinjärvi/Finland Mine Water with Zero-valent Iron and Iron Waste as Alternative Iron Sources

Mine Water and the Environment - Nitrate reduction was optimized in water from the Siilinjärvi/Finland mine site with iron powder and iron nanoparticles. Iron waste from a mold machining...     

Experimental design of application of nanoscale iron-nickel under sonication and static magnetic field for mixed waste remediation

In this paper, the degradation of simulated mixed organics commonly found in nuclear waste streams was studied under a combined influence of sonication and magnetic field. Nanoscale bimetallic iron-nickel was used as source of Fenton reaction. The data were fitted to obey second order kinetics. The extent of degradation followed the trend: TBP-EDTA-citric acid greater than TBP-EDTA, greater than TBP alone. The influence of the three variables that govern degradation behaviour viz. sonication energy, magnetic field and time were evaluated with response surface methodology. The model could predict the ratio of total organic carbon content to a maximum error of only ～ 6%.     

Defluoridation from aqueous solutions by nano-alumina: characterization and sorption studies

The present study was conducted to evaluate the feasibility of nano-alumina (Al(2)O(3)) for fluoride adsorption from aqueous solutions. The nature and morphology of pure and fluoride-sorbed nano-alumina were characterized by SEM with EDX, XRD, and FTIR analysis. Batch adsorption studies were performed as a function of contact time, initial fluoride concentration, temperature, pH and influence of competing anions. Fluoride sorption kinetics was well fitted by pseudo-second-order model. The maximum sorption capacity of nano-alumina for fluoride removal was found to be 14.0 mg g(-1) at 25°C. Maximum fluoride removal occurred at pH 6.15. The fluoride sorption has been well explained using Langmuir isotherm model. Fluoride sorption was mainly influenced by the presence of PO(4)(3-), SO(4)(2-) and CO(3)(2-) ions.     

Antimicrobial activity of weak acids in liquid feed fermentations, and its effects on yeasts and lactic acid bacteria

BACKGROUND: The efficacy of weak organic acids in the control of yeasts in pig liquid feed was studied taking into account the effects on lactic acid bacteria (LAB) responsible for beneficial fermentation. RESULTS: The yeast population in pig liquid feed was taxonomically identified. Kazachstania exigua, Debaryomyces hansenii and Pichia deserticola dominated the fermentation in liquid feed and whey. Pichia deserticola was found in whey and foaming liquid feed and dominated the fermentation after incubation. The sensitivity of the isolates against weak acids was measured in culture medium as well as in fermented and non‐fermented liquid feed. Formic acid and potassium sorbate successfully reduced the growth of yeasts in all media without interfering with LAB development. Both of these organic acids showed an increased antifungal effect when used in liquid feed fermented by a Lactobacillus plantarum strain. CONCLUSION: The loss of energy, reduced palatability and other practical problems due to the high growth of yeasts in fermented liquid diets can be reduced by organic acids without affecting lactic acid fermentation. Copyright © 2011 Society of Chemical Industry     

Sewage Sludge Electro-Dewatering Treatment—A Review

Purification of municipal wastewater generates huge amounts of sewage sludge, which contains large quantities of water, biomass, and extracellular polymeric substances. It is widely known that sewage sludge usually has a poor dewaterability. A large amount of water in sludge directly translates into high transport and handling costs; therefore, sludge treatment and disposal usually requires over 50% of the operation budget for wastewater treatment plants. The application of a low electric field through the sludge segment, called electro-dewatering, is considered to improve the liquid–solid separation, resulting in low water content in the sludge cake. However, prediction of dewatering enhancement for sewage sludge, in particular, offers a challenge due to variations in sludge pretreatment practices and the lack of harmonized testing methodologies. In this review article, the aspects that have an effect on sewage sludge electro-dewatering and its feasibility are discussed in the light of recent technological developments. It was found that electro-dewatering has several potential benefits, such as removal of pathogens, reduction in energy and transportation costs, and prevention of filter fouling.     

Fractionation of Macro and Trace Metals Due to Off-Time Interrupted Electrodewatering

Electrodewatering with interrupted voltage was set up to investigate the effects of long off-time interruption on solid content in the final sludge cake and the fractionation of macro and trace elements in the sludge matrix. In comparison to continuous direct current (DC) electrodewatering, long off-time interruption had a negative effect on water removal, resulting in a high water content in sludge at anode and the final sludge cake. However, long off-time interrupted electrodewatering significantly increased dry solid (DS) content in the final sludge cake in comparison to control experiments. Removal of Na⁺ and K⁺ from sludge was affected by long off-time interruption. The long off-time interruption also negatively influenced the dissolution and migration of macro (Ca, Mg, and Fe) and trace (Ni, Mn, and Zn) metals in sludge cake matrix. The long off-time interrupted voltage application did not have any effect on the chromium concentrations in sludge at the anode; however, the chromium concentrations in the removed water at the anode significantly depended on off-time interruption.