Manuel A. Manzano

The effect of temperature on the biodegradation of a nonylphenol polyethoxylate in river water

Abstract In this paper a study is made of the biodegradability of a non-ionic surfactant, a nonylphenol polyethoxylate, in river water by means of monitoring the residual surfactant matter and the metabolites that may be generated. The influence of temperature on the extent of primary and ultimate biodegradation, and the kinetics of degradation are also determined. The method used was the river die-away test, and the biodegradation process was monitored by normal and reversed phase high-performance liquid chromatography (HPLC). These results are supported by other indirect measurements and indicators of the existence of microbial degradation process, as well as the parameters for the control of the process. The results obtained indicate that temperature has a strong influence on the period of acclimation of the microorganisms and on the rate of biodegradation. The percentages of primary biodegradation vary from 68% at 7°C to 96% at 25°C, and at all the temperatures studied, metabolites are generated during the biodegradation process which do not totally disappear at the end of the assay. The percentages of mineralization reached in the various assays, ranging from 30% at 7°C to 70% at 25°C, also show the great influence of temperature. Finally, a kinetic study of the biodegradation process has been carried out, with excellent fit of the experimental data to the kinetic model of Quiroga and Sales.

Solar photocatalytic water disinfection of Escherichia coli, Enterococcus spp. and Clostridium Perfringens using different low-cost devices

BACKGROUND The purpose of this work was to evaluate the disinfection capacity of two handmade low-cost devices based on solar photocatalytic disinfection (SPC-DIS): a plastic bottle (2 L) with a cylinder inside coated with TiO2 doped with zinc and a glass reactor (9 L) with an inner cylinder coated with pure TiO2. Disinfection experiments of wastewater-derived Escherichia coli, Enterococcus spp. and Clostridium perfringens (104–105 CFU per 100 mL) were carried out under natural sunlight during winter. RESULTS Clostridium perfringens was the most resistant microorganism and E. coli the least in all cases. The SPC-DIS bottle achieved 100% disinfection for E. coli, but only 98.97% for Enterococcus spp. and 96.28% for C. perfringens. The SPC-DIS reactor achieved, under optimum operating conditions, 100% disinfection for E. coli, 100% for Enterococcus spp. and 99.44% for C. perfringens. Maximum sustainable flow rate (22 L min−1) and maximum illumination ratio (1:2) were the best operating conditions. Operating with recirculation (interrupted illumination) favored C. perfringens spore formation. Best kinetic models were biphasic for E. coli and log-linear for Enterococcus spp. and C. perfringens. CONCLUSION The two new devices showed higher disinfection capacity than common PET bottles (increase in disinfection rates up to 1.5 and 4.6 times), proving to be promising alternatives to the traditional method SODIS.

Disinfection of Natural Water by Solar Photocatalysis Using Immobilized TiO2 Devices: Efficiency in Eliminating Indicator Bacteria and Operating Life of the System

Natural water has been disinfected using TiO2 as the fixed catalyst incorporated in a homemade photoreactor, in which the dimensions and the design parameters are representative of devices that are currently employed at larger scale. The catalyst was immobilized on the external surface of a cylinder of frosted glass situated in the longitudinal axis of a tubular glass reactor. Two alternative methods of immobilizing the catalyst on glass were studied: in the first, a commercial titanium oxide powder (Aeroxide R TiO2 P25) was mounted on a polymeric support; and in the second, it was applied by sol-gel deposition. Illumination was effected by installing the glass reactor in the irradiation chamber of a solar simulator. Under laboratory conditions, groundwater contaminated with cultured and wild bacteria was treated photocatalytically, and the influence of the photolysis, the pumping, and the catalysts was studied. The results obtained have demonstrated that the catalyst immobilized in the interior of the photoreactor presents similar results, in the disinfection of E. coli, as 0.5 g/l of TiO2 P25; and that, in 1.5 h approximately of simulated solar illumination (167 kWUVA s/m ) on the sol-gel deposit of TiO2, it is possible to eliminate 100% of the bacteria covered by international regulations in respect of water for human consumption. With regard to the aging assay of the system, it was observed at 250 h of operation a reduction in the effectiveness of the disinfection process. At 0 and 250 h of operation, the percentages of elimination of E. coli after 50 min of illumination were 100% and 99.5%, respectively. This reduction in the effectiveness of the process was due to the formation of a film of calcium carbonate adhering to the internal glass wall of the photoreactor, which is in contact with the liquid being treated, and to the presence of calcium carbonate precipitates on catalyst surface. [DOI: 10.1115/1.4005338]

Biodisposition of linear alkylbenzene sulphonates and their associated sulphophenyl carboxilic acid metabolites in sea water

Abstract The present paper describes the results of the application of the biodegradation assay proposed by the United States Environmental Protection Agency “Biodegradability in sea water” Office of Prevention, Pesticides, and Toxic Substances 835.3160, in shaked flask, to linear alkylbenzene sulphonate (LAS), the synthetic surfactant with the highest consumption volume on a world-wide basis. The concentration of sulphophenyl carboxylic acids (SPCs) which are the main metabolites of LAS have also been monitored by high performance liquid chromatography. The experiment were conducted using water originating from the Bay of Cadiz (in the South West of the Iberian peninsula). The results indicate that LAS was rapidly biodegraded. SPCs were transiently produced during the process and they were biodegraded to levels below the limits of detection (136 μg / l ) after 42 days of assay. The kinetic of biodegradation of the surfactant and its biointermediates have been modeled; half-life times of 6.2 days for the primary biodegradation of LAS and of 9.6 days for the mineralization of the biointermediates were obtained.

Solar Photocatalytic Water Disinfection of Escherichia coli, Enterococcus spp. and Clostridium Perfringens using different low-cost devices

BACKGROUND The purpose of this work was to evaluate the disinfection capacity of two handmade low-cost devices based on solar photocatalytic disinfection (SPC-DIS): a plastic bottle (2 L) with a cylinder inside coated with TiO2 doped with zinc and a glass reactor (9 L) with an inner cylinder coated with pure TiO2. Disinfection experiments of wastewater-derived Escherichia coli, Enterococcus spp. and Clostridium perfringens (104–105 CFU per 100 mL) were carried out under natural sunlight during winter. RESULTS Clostridium perfringens was the most resistant microorganism and E. coli the least in all cases. The SPC-DIS bottle achieved 100% disinfection for E. coli, but only 98.97% for Enterococcus spp. and 96.28% for C. perfringens. The SPC-DIS reactor achieved, under optimum operating conditions, 100% disinfection for E. coli, 100% for Enterococcus spp. and 99.44% for C. perfringens. Maximum sustainable flow rate (22 L min−1) and maximum illumination ratio (1:2) were the best operating conditions. Operating with recirculation (interrupted illumination) favored C. perfringens spore formation. Best kinetic models were biphasic for E. coli and log-linear for Enterococcus spp. and C. perfringens. CONCLUSION The two new devices showed higher disinfection capacity than common PET bottles (increase in disinfection rates up to 1.5 and 4.6 times), proving to be promising alternatives to the traditional method SODIS.

Molecular structure and biodegradation kinetics of linear alkylbenzene sulphonates in sea water

The present paper describes the results of the application of the biodegradation test proposed by the United States Environmental Protection Agency (USEPA) “Biodegradability in sea water” Office of Prevention, Pesticides, and Toxic Substances (OPPTS) 835.3160, to Linear Alkylbenzene Sulphonate (LAS), the synthetic surfactant with the highest consumption volume on a world-wide basis. High performance liquid chromatography (HPLC) has been employed for the separation and quantification of the different homologues and isomers of the surfactant. Water from the Bay of Cádiz (South–West of the Iberian peninsula) has been used as test medium. The results indicate how both lag and t50 time shows a significant linear relationship with the length of the alkyl chain of the homologue; the effect of this is that the homologues of longer chain length not only begin to degrade first but also degrade at a faster rate. Regarding the isomeric composition, it is observed that as the percentage of biodegradation increases, there is an increase in the proportion of internal isomers, in comparison with the isomeric relationships of the original test substance

Microbial Degradation and Chemical Oxidation of Sandy Sediment Contaminated with Polychlorinated Biphenyl

This paper reports the results of various biodegradation experiments on polychlorinated biphenyl (PCB)-contaminated sandy sediment employing a mixed culture of acclimatized bacteria. Following the optimization of different variables, the elimination rate achieved of Aroclor 1242 in slurry phase reactors was 61% after 4 months of treatment. The presence of biphenyl as a cosubstrate was the most important factor affecting PCB biodegradation. The biodegradation occurred as a first-order process, and proved most effective with respect to dichlorinated (100% removal), followed by trichlorinated (92%) and tetrachlorinated biphenyls (24%). The results of the treatment of polychlorinated biphenyl (PCB) contaminated sandy sediment with the Fenton advanced oxidation process (AOP) confirm that the oxidation process occurs on the PCBs adsorbed to particles, producing 98% elimination of the original PCB structure after 72 h. The degree of elimination was found to be dependent on the level of congener chlorination, and...

Combining sun-based technologies (microalgae and solar disinfection) for urban wastewater regeneration

Solar disinfection (SODIS) of urban wastewater can be a suitable technology for improving the microbiological quality of reclaimed water as a complement to other extensive and environmentally friendly technologies such as microalgae biotreatment. The objective of this work is to evaluate the feasibility of incorporating the SODIS technology at the end of a pilot scale urban wastewater treatment plant (WWTP) where the processes are based on microalgae biotechnology and comprising three Upflow Anaerobic Sludge Blanket (UASB, 20m3 each one) reactor, six High Rate Algal Ponds (HRAP, 32m2 each one), and a Dissolved Air Flotation (DAF, 1m3) unit. E. coli concentration was monitored at the effluent of the different units (UASB, HRAP, DAF) of the pilot WWTP. The efficiency of the SODIS process was studied for the inactivation of three of the commonly employed indicator microorganisms (Escherichia coli, Enterococcus spp. and Clostridium perfringens) using a compound parabolic collector (CPC) for five months under various conditions of irradiance and temperature. E. coli and Enterococcus spp. were more effectively disinfected by the SODIS unit (2.9 and 2.5 logarithms of reduction on average, respectively) than by the HRAP (2 and 1.1) or the DAF (0.9 and 0.1). On the contrary, the DAF technology achieved better reduction rates of C. perfringens (1.7) than the SODIS (0.9) and the HRAP (0.1). No regrowth of any microorganisms was detected during dark storage after the SODIS treatment. Incorporating a SODIS unit after the non-conventional WWTP processes substantially increases the possibilities for reuse of the treated water after receiving a cumulative UV radiation dose of 25W·h/m2 (50min of normalized time of solar illumination). The surface requirement of the SODIS equipment would be 3.5 times smaller than the HRAPs surface.