A film-stacking technique was used to estimate diffusion coefficients of polybrominated diphenyl ethers (PBDEs) in low density polyethylene (LDPE) and silicone rubber. Substantially higher PBDE diffusion coefficients were observed for silicone rubber (AlteSil™) than for LDPE. A much steeper decrease in LDPE diffusion coefficients was found with increasing PBDE molecular weight than that for silicone rubber. From a passive sampling point-of-view, this means that for equivalent polymer-water partition coefficients for these two materials, the mass transfer resistance for these substances in the LDPE will be significantly higher than that for silicone rubber. Boundary layer control of the uptake process for silicone rubber can be expected for PBDEs. With a microplastic perspective, the low diffusion coefficients of PBDEs and in particular of decabromo diphenyl ether (BDE 209) in LDPE imply that the polymer diffusion coefficients for these plastic additives used as flame retardants need to be taken into account when considering the risk posed by microplastic particle ingestion by marine organisms.

Hepatitis E virus (HEV) is one of the main causes of acute viral hepatitis of enteric transmission. HEV has been detected in environmental samples in several countries from Europe and Asia, constituting a risk factor for waterborne infection. In Colombia, HEV has been identified in samples obtained from patients as well as from swine, but no environmental studies have been carried out. To determine if HEV is present in environmental waters, samples from the main source of drinking water plant and of wastewater system of eight municipalities and two villages of Antioquia state (North West Colombia), were collected between December 2012 and April 2014. The HEV genome was detected by RT-PCR in 23.3% (7/30) of the samples from the main source of drinking water plants and in 16.7% (5/30) from sewage. Viral concentrates obtained from three positive sewage samples were used to inoculate HepG2 cell cultures that were followed for one month; however, the viral genome was not detected in any cell culture. This study demonstrates the circulation of HEV in both source of drinking water plants and wastewater in Antioquia state, Colombia. The presence of HEV in environmental waters could be a risk for waterborne transmission in this population. The findings of the present study, together with the evidence of HEV circulation in human and swine in Colombia, should be consider by public health authorities for the development of surveillance programs and the inclusion of HEV infection diagnosis in the guidelines of viral hepatitis in the country. This is the first report of HEV in environmental samples in Colombia and the second one in Latin America.

A 1.1 m3 hybrid USBF fully instrumented pilot plant has been used for the treatment of diluted wine for four years. In this work, the performance of the wastewater treatment plant (WWTP) during start up and operation (normal operation and overload experiments) is shown. A complete description of the treatment process behaviour (gas and liquid phase composition and anaerobic sludge characteristics) is given by on-line and off-line monitoring of 28 process variables. The results presented here demonstrate the reliability of this technology for the treatment of wastewater from seasonal processes, such as winery wastewaters, during a long period of time (four years). Furthermore, the USBF reactor presented very short start up periods after short and long shut down of the WWTP and rapidly turned back to normal operation after suffering a complete destabilization due to organic overload. Both effluent and biogas were of good quality. Dissolved organic carbon concentration in the effluent was always lower than 100 mg DOC l(-1) under normal operation, while methane concentration in the biogas was in the range 70-74%, making it suitable for energy recovering.

In this work, a fuzzy logic-based system for diagnosis and control of an anaerobic wastewater treatment plant was developed. Three variables (methane production, hydrogen concentration in the gas phase, and intermediate alkalinity/total alkalinity ratio) were selected, according to previous works, as the more adequate for organic overload identification. The diagnosis and control system was developed using expert's knowledge related with normal or overload process states for establishing a set of rules considering the selected variables. The control system computes the feed flow rate for adjusting the organic load applied to the reactor. The control law is based on a response surface obtained according to fuzzy inference Mamdani methodology. The diagnosis and control system was validated at three different levels: (a) simulation with ADM1 (wastewater containing ethanol); (b) open-loop methodology using experimental data from a hybrid upflow sludge bed-filter (USBF) anaerobic pilot plant treating a wastewater containing ethanol; and (c) closed-loop control of a USBF pilot plant treating wastewater containing carbohydrates. The proposed system diagnoses correctly the different episodes, and it demonstrated a high reliability, supplying an adequate control action to achieve the desired set point as well as to manage a sudden change in influent COD. Moreover, the performance of the developed system can depend slightly of the noise in the measured variables used for determining the process state.

An easy-to-implement controller based on gas phase measurements for anaerobic digestion processes was developed. The controller is based on the indirect control of COD in the effluent by means of controlling the hydrogen concentration in the biogas. The fast response of hydrogen under destabilizations, such as those caused by overloads, guarantees an early actuation on the system before it destabilizes. The controller is designed such that it brings the anaerobic digestion process to maximum capacity by pushing it to maximum methane production as long as hydrogen remains low. Experiments have been conducted to test the controller under organic over- and underload situations and promising performance was achieved. Further experiments must be carried out to validate the controller under a wider spectrum of situations to enable its robust industrial application.

No abstract

This paper describes a validation procedure applied for an on-line titrimetric analyzer (AnaSense ® -Anaerobic Control Analyzer) prototype designed to detect of volatile fatty acids (VFA) and alkalinity (bicarbonate). The AnaSense ® analyzer was recently developed under the framework of the TELEMAC European Project. A pilot-scale evaluation of the analyzer was carried out in an anaerobic wastewater treatment plant, in a hybrid Upflow Sludge Bed Filter (USBF) reactor with an overall volume of 1.15 m 3 . The sensor uses two methods, both based on two-point titrimetric analyses, for determining VFA and alkalinity concentration. AnaSense ® performed on-line monitoring of VFA (13-4,900 mg и L Ϫ1 ) and bicarbonate (2.5-49.5 mEq и L Ϫ1 ), and demonstrated sufficient accuracy for both VFA and bicarbonate detection. Intermediate Alkalinity/Total Alkalinity (IA/TA) and Intermediate Alkalinity/Partial Alkalinity (IA/PA) ratios were also evaluated to test the suitability of the sensor for anaerobic digestion process control.

This work aims to systematize the study of indicators for two types of wastewaters: carbohydrate-based and protein-based synthetic wastewaters. Characterization of steady states and dynamic response analysis against disturbances were carried out using both a factorial discriminant analysis (FDA) and a phenomenological analysis, respectively. This research seeks reconciling both sets of indicators in order to optimize resources and provide a minimal cost in instrumentation for its implementation at industrial scale. According to the results of this research, the best indicators for the two types of wastewaters, considering both process steady states and organic load perturbations are: Biogas flow rate or Methane flow rate, and Hydrogen concentration in the biogas; Volatile fatty acids and Partial alkalinity in the liquid phase.