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The removal performances of each technology, its energy costs and the possible lack of qualified personnel in small population centres to implement the most suitable technology needs to be assessed. Likewise, the amount of wastewater to be treated and its intended subsequent use are fundamental aspects in deciding on which technology to apply. In the event that the water is to be reused, the use of membrane technologies in conventional plants and intermittent filters in the case of non-conventional plants have proven their effectiveness in removing different types of emerging contaminants. This paper reports the results obtained in the implementation of the aforementioned technologies for the removal of caffeine, theobromine, theophylline, amoxicillin and penicillin G, making a comparison between the removal performance, the amount of wastewater treated per day and the energy costs involved. The technologies under study reduce pollutants by over 99%, and the water can be reused in almost all options. As for the energy used by each methodology, it can be seen that the maximum amount of water treated per day at maximum flow rate in intermittent sand filters is 70 L per day. While with the membranes, between 500 and 1000 L per day are obtained. However, the membranes need more energy consumption, as well as qualified personnel for their use and maintenance. This leads to higher production costs. Intermittent filters provide evidence that it can be of great applicability in small populations, while the membranes should be used in terms of cost and for large populations.

PURPOSE: To evaluate changes in the epidemiology of mechanical ventilation in Spain from 1998 to 2016. DESIGN: A post hoc analysis of four cohort studies was carried out. SETTING: A total of 138 Spanish ICUs. PATIENTS: A sample of 4293 patients requiring invasive mechanical ventilation for more than 12h or noninvasive ventilation for more than 1h. INTERVENTIONS: None. VARIABLES OF INTEREST: Demographic variables, reason for mechanical ventilation, variables related to ventilatory support (ventilation mode, tidal volume, PEEP, airway pressures), complications during mechanical ventilation, duration of mechanical ventilation, ICU stay and ICU mortality. RESULTS: There was an increase in severity (SAPSII: 43 points in 1998 vs. 47 points in 2016), changes in the reason for mechanical ventilation (decrease in chronic obstructive pulmonary disease and acute respiratory failure secondary to trauma, and increase in neurological disease and post-cardiac arrest). There was an increase in noninvasive mechanical ventilation as the first mode of ventilatory support (p

Pharmaceutical products, as well as insecticides and antimicrobials, have been extensively studied, but knowledge of their effects—especially those caused by their mixtures with microplastics— on aquatic organisms remains limited. However, it should be borne in mind that the state of knowledge on acute and chronic effects in aquatic organisms for pharmaceuticals and pesticides is not similar. In response, this investigation analyzed the presence of microplastics (polyvinyl chloride) and their impacts on the toxicity of chlorpyrifos (an insecticide) and triclosan (an antibacterial) when they coincide in the environment, alongside the two most consumed drugs of their type (hypolipemic and anticonvulsant, respectively), namely simvastatin and carbamazepine, in Artemia salina. LC50 and cholinesterase enzyme activity were calculated to determine the possible neurotoxicity associated with emergent contaminants in the treatments. The LC50 values obtained were 0.006 mg/dm3 for chlorpyrifos, 0.012 mg/dm3 for chlorpyrifos associated with microplastics, 4.979 mg/dm3 for triclosan, 4.957 mg/dm3 for triclosan associated with microplastics, 9.35 mg/dm3 for simvastatin, 10.29 mg/dm3 for simvastatin associated with microplastics, 43.25 mg/dm3 for carbamazepine and 46.50 mg/dm3 for carbamazepine associated with microplastics in acute exposure. These results indicate that the presence of microplastics in the medium reduces toxicity, considering the LC50 values. However, exposure to chlorpyrifos and carbamazepine, both alone and associated with microplastics, showed a decline in cholinesterase activity, confirming their neurotoxic effect. Nevertheless, no significant differences were observed with the biomarker cholinesterase between the toxicant and the toxicant with microplastics., This research was funded by the Ministerio de Ciencia, Investigacion y Universidades (REF.: RTI2018-096771-B-100).

Effluents from wastewater treatment plants (WWTPs) are widely recognized as the main source of emerging contaminants (stimulants and antibiotics). In this study, intermittent sand and/or coke filters were installed as a tertiary treatment at the outlet of a secondary settling tank at the WWTP in Medina Sidonia, Spain. Regular sampling followed by solid-phase extraction (SPE) and analysis by liquid chromatography-mass spectrometry (UPLC-MS) showed the complete removal of the concentrations of the emerging contaminants (caffeine, theobromine, theophylline, amoxicillin and penicillin G). Moreover, optimal filtration conditions for the reuse of treated water were presented.

The increase in microplastics (MPs) research has aroused awareness about their presence and polluting potential in aquatic environments. Wastewater treatment plants (WWTPs) have been identified as one of the main paths for these pollutants to reach the environment. The present study is focussed in the WWTPs emplaced within the Guadalete-Barbate river basin. This geographical area comprises a total of 60 WWTPs treatment plants with an inhabitant equivalent (IE) above 250. Within these 60 wastewater treatment plants, there are 38 plants with conventional treatments and an estimated population of over 800,000. The high percentage of population that lives in this basin leads us to think about the quantity of microplastics that are dumped into the environment daily. Therefore, the aim of this research is to study the occurrence and identify the type of microplastics in these facilities, this information is important in order to design treatments that improve microplastics removal and avoid their entrance in the aquatic environment.

Objetivo: Evaluar cambios en la epidemiología de la ventilación mecánica en España desde 1998 hasta 2016. Diseño: Análisis post-hoc de 4 estudios de cohortes. Ámbito: Un total de 138 UCI españolas. Pacientes: Un total de 4.293 enfermos con ventilación mecánica invasiva más de 12 h o no invasiva más de 1 h. Intervenciones: Ninguna. Variables de interés principales: Demográficas, motivo de ventilación mecánica, relacionadas con el soporte ventilatorio (modo de ventilación, volumen tidal, PEEP, presiones en vía aérea), complicaciones, duración de la ventilación mecánica, estancia y mortalidad en la UCI. Resultados: Se observa aumento en la gravedad (SAPS II: 43 puntos en 1998 frente a 47 puntos en 2016), cambios en el motivo de la ventilación mecánica (disminución de la enfermedad pulmonar obstructiva crónica e insuficiencia respiratoria secundaria a traumatismo y aumento de la patología neurológica y tras parada cardiaca). Aumento en la ventilación no invasiva como primer modo de soporte ventilatorio (p < 0,001). El modo más utilizado es la ventilación controlada por volumen con un aumento de la presión de soporte y de la ventilación controlada por volumen regulada por presión. Disminuyó el volumen tidal (9 ml/kg de peso estimado en 1998 y 6,6 ml/kg en 2016, p < 0,001) y aumentó la PEEP (3 cmH2O en 1998 y 6 cmH2O en 2016, p < 0,001). La mortalidad disminuye (34% en 1998 y 27% en 2016; p < 0,001) sin variabilidad geográfica (MOR 1,43; p = 0,258). Conclusiones: Se observa una disminución en la mortalidad de los enfermos ventilados en UCI españolas. Esta disminución podría estar relacionada con cambios para minimizar el daño inducido por el ventilador. pre-print 1473 KB

Studies were conducted to assess the biodegradability and toxicity of the cationic surfactant dodecyl trimethyl ammonium chloride (DTMAC) in sea water samples collected from the Gulf of Cadiz (Spain). Ultimate biodegradation was studied following the guideline proposed by the United States Environmental Protection Agency (USEPA). Growth inhibition tests on five marine microalgae species and mortality tests on a marine crustacean (Artemia franciscana) were carried out. Biodegradation process was modelled according to a logistic kinetic model. Lag time and half-life were 15.17 and 26.95 days, respectively. Depending on the microalgae, 96-h EC50 values ranged from 0.69 to 6.34 mg L−1 DTMAC, respectively. 48-h and 72-h LC50 to A. franciscana were 46.74 and 34.19 mg L−1 DTMAC, respectively. The results indicate that DTMAC can be mineralised in sea water. Marine crustacean was more resistant than the microalgae. Surfactant tolerance on microalgae followed this order: T. chuii > N. gaditana > C. gracilis ≈ I. galbana ≈ D. salina, being the Green microalgae T. chuii the most tolerant.

Pollution from plastics and their slow degradation are current problems that require urgent solutions. The natural degradation of plastics leads to its fragmentation, resulting not only in microplastics (MPs) but also in nanoplastics (NPs). In recent years, research and monitoring of MPs and NPs concentrations has increased. The monitoring of their concentrations in the environment, sampling sites, detection and quantification methods are not standardised due to the inherent properties of the materials and the origin of the samples, which tends to make the comparison of data between different studies difficult. In this study, we developed an H2O2-enzyme protocol for the extraction of MPs from sludge based on existing analytical methods in the literature, from sampling to quantification and detection. Our laboratory study consists of four protocols used to verify MPs recovery from doped sludge samples containing three polymers (polypropylene, polyethylene terephthalate and nylon). To emphasise the relevance of the optimal protocol, a triplicate test was performed for each of these protocols, all of them using sieve fractions between 100 and 500 μm, while isoporous polycarbonate membranes were used for the filtration of the samples. The percentage polymer distribution of H2O2-enzyme protocol was similar to the control (42% ± 8.49; 38% ± 2.83; 16% ± 11.31), with some limitations for the larger fraction. Data collection was carried out by optical visualisation and chemical identification using Fourier-transform infrared spectroscopy to record polymer spectra obtained for potential interpretation. Finally, a test was conducted to try all protocols on a real sludge from a local plant to confirm their efficiency.

Wastewater treatment plants (WWTPs) have been appointed as one of the main sources of microplastics (MP) into marine ecosystems. The aim of this research work has been to study the influent and effluent of two WWTPs, both located in Cadiz, with different wastewater source (industrial and urban), as well as the receiving water bodies where the facilities discharge their sewage. MP were collected, extracted from wastewater matrixes and analysed according to the abundance, shape, size, and type of polymer, along with the removal rates of MPs in the plants. Subsequently, the data obtained on both WWTPs were compared, the main difference among the WWTPs was the amount of microplastics found in the wastewater, as well as the presence of polymers with resins from industrial activities. The results from this study established that the most representative form was fibers; about the size, 100–355 μm fraction was the most abundant, followed by 355–1000 μm and finally the size among 1000–5000 μm. Regarding to the type of polymers, 17 were identified using attenuated total refraction Fourier-transformed infrared spectroscopy (ATR-FTIR). Further, PVC, PE, EAA and HDPE were the largest found polymers. The presence of MPs in the influent varied from 645.03 ± 182.24 MPs/L to 1567.49 ± 413.18 MPs/L in the urban and industrial WWTP respectively; in the effluent, it varied from 16.40 ± 7.85 MPs/L to 131.35 ± 95.36 MPs/L. The removal rate overcome the 90% in all the samples. Receiving water bodies presented heterogeneous abundance of microplastics 6.64 ± 2.71 MPs/L and 0.83 ± 0.26 MPs/L in the zones close to IWWTP and UWWTP discharge point. The results obtained shows that despite the elimination efficiency in the WWTPs studied, these facilities act as a significant source of MPs into aquatic ecosystem due to large flow of water discharged.

Sludge production is an undesirable by-product of biological wastewater treatment. The oxic-settling-anaerobic (OSA) process constitutes one of the most promising techniques for reducing the sludge produced at the treatment plant without negative consequences for its overall performance. In the present study, the OSA process is applied in combination with ultrasound treatment, a lysis technique, in a lab-scale wastewater treatment plant to assess whether sludge reduction is enhanced as a result of mechanical treatment. Reported sludge reductions of 45.72% and 78.56% were obtained for the two regimes of combined treatment tested in this study during two respective stages: UO1 and UO2. During the UO1 stage, the general performance and nutrient removal improved, obtaining 47.28% TN removal versus 21.95% in the conventional stage. However, the performance of the system was seriously damaged during the UO2 stage. Increases in dehydrogenase and protease activities were observed during both stages. The advantages of the combined process are not necessarily economic, but operational, as US treatment acts as contributing factor in the OSA process, inducing mechanisms that lead to sludge reduction in the OSA process and improving performance parameters.

Wastewater treatment plants that are close to the coast and sea level often have problems with seawater intrusion. Because of this, three saline intrusions of 2%, 5% and 10% in volume (socks 1, 2 and 3 respectively) were carried out using actual wastewater. As a technology, a sequential biofilm batch reactor operating an enhanced biological phosphorus removal process was studied. The main focus of the study lies in the impact on the plant's nutrient removal performance during these seawater intrusion events until achieving system recovery. During the study a constant salinity profile was observed without large variations in the reactor after reproducing the seawater intrusions. The COD removal rate decreased below 80% and 65.4% for shock 2 and 3 respectively. In a seawater intrusion of 2% and 5% in volume, corresponding to shocks 1 and 2, TN removal decreased to 66.4% and 71.5%, respectively, and was subsequently restored to previous removal rate values (> 80%) 4 days after the shocks, in both cases. TP removal was negative after every shock due to increased concentrations in the effluent resulting from deficient PAO activity. This situation lasted for 9, 10 and 14 days for shocks 1, 2 and 3, respectively, until recovery of performance to the same levels as prior to the shocks.

In this paper, the pyrolysis and combustion of sediment have been compared using thermogravimetric analysis (TG) coupled with Fourier transform infrared spectrometry (TG-FTIR) analysis. The TG results showed that both the pyrolysis and combustion of sediment presented four weight loss stages, each. The evolving gaseous products during pyrolysis were H 2 O, CO 2 and hydrocarbons, while combustion yielded considerable amounts of CO 2 , in addition to H 2 O, CO, C C, C O and NH 3 . Comparing the pyrolysis and combustion TG-FTIR curves, it is possible to evaluate the effect of oxygen presence in the temperature range of 200–600 °C, which increases the volatilisation rate of organic matter in sediment. For the better detection of organic and inorganic matter in sediment by TG-FTIR analysis it is recommended to work in combustion mode of sediment.

The production of excess sludge in the conventional activated sludge (CAS) process is an important aspect of the operation of wastewater treatment plants. The oxic-settling-anaerobic (OSA) process is one of the most promising strategies among those to achieve a reduction in the excess sludge produced. Cell decay occurs at a low oxidation–reduction potential and subsequent degradation reactions seem to be the major causes of sludge reduction in the OSA process. As a consequence of previous exposure of the sludge to anaerobic conditions in the sludge holding tank, an increase of enzymatic and microbiological activity in the aeration reactor could enhance the degradation of the released material. In this study, the results of a pilot plant running sequentially as a CAS and a CAS-OSA system are shown not only in the terms of the crucial aspect of excess sludge reduction, but also in terms of enzymatic and microbiological activities in the sludge from the aeration tank. Specifically, the application of...

This paper presents the results obtained in the degradation of ibuprofen by ozonation. This study aims to evaluate the degradation of ibuprofen by ozonation once the operating variables have been optimized, investigating the degradation and degradation efficiency of the compound and assessing the toxic effect of ibuprofen and of the intermediate compounds generated during oxidative treatment. Work was carried out to optimize the four operating variables: pH, conductivity, hydraulic retention time and the use of a maze of pipes to enhance contact between the ozone and the drug. All the trials were conducted in a purpose-built pilot-scale reactor. Analyses of the compound were carried out after solid–liquid phase extraction on high resolution liquid chromatography (HPLC). Working under optimal operating conditions (pH = 9, HRT = 20 min and 12 ± 2 gN/m 3 ), a degradation value of 99% was obtained, although degradation efficiency or mineralization of the compound was not achieved. The toxicity of ibuprofen and its intermediate compounds formed during the oxidative process was likewise studied. This toxicity was found to increase with increasing initial concentrations of the compound, with the intermediate compounds thus formed being more toxic than the starting compound.

Sewage sludge production is currently considered as one of the most important problems in wastewater treatment due to the high costs of management and treatment, as well as limitations in its final use. In accordance with the order of priority in waste management options, based on the 3Rs’ (reduce, reuse and recycle), numerous studies are addressing this need to minimize the sewage sludge production. This paper presents a review of recent studies in the field of sewage sludge minimisation, focusing on the techniques based on the cell lysis and cryptic growth mechanism. In addition to reducing sludge, the cell lysis-cryptic growth technologies applied in the sludge return line provide, biodegradable carbonaceous matter that aids denitrification. The promising results obtained in the full-scale application of some of the cell lysis-cryptic growth technologies constitute yet another advantage of this strategy.

The biodegradation of a non‐ionic surfactant was evaluated by the evolution of the microbial activity and the determination of the soluble surfactant present in the effluent. Two lab‐activated sludge reactors/systems were fed with synthetic sewage, one of which received in addition different concentrations – 5 and 10 mg/L – of nonylphenol ethoxylates (NPEO). The parameters employed in this assay were: control parameters (COD and SS) and activity microbial parameters (specific oxygen uptake rate and dehydrogenase activity). The removal of NPEO and the production of secondary metabolites were monitored. Solid‐phase extraction and HPLC with fluorescence detection were employed for sample preparation and analysis. The results suggest that the microbial activity was not inhibited when 5 mg/L of NPEO was added. Nevertheless, an important inhibition of the general metabolism was observed for 10 mg/L of NPEO.

Fixed biomass technologies, such as rotating biological contactors or biodiscs, have been applied for wastewater depuration both in large and medium-small-sized agglomerations. Biofilm's composition and microorganism activity are essential parameters for the successful operation and control of these systems. Biofilm's thickness and total dry weight have been widely used for biofilm's characterization but, actually, are not sufficient to describe biofilm activity. In fact, biofilm's activity is not proportional to the quantity of fixed biomass, but increases with the thickness of biofilm up to a determined level called the "active thickness". Above this level, the diffusion of nutrients through the film becomes a limiting factor. A stable, thin, and active biofilm thus offers numerous advantages in water and wastewater treatment. Different parameters have been used to evaluate biofilm's activity. The specific oxygen uptake rate, INT-dehydrogenase activity, and the ratio active/total cells have been applied for that purpose. These methods are not only simple and rapid but also sensitive, precise, and representative. The results obtained confirm the potential of the microbial activity measurements studied for an accurate biofilm's characterization and biomass activity estimation in fundamental research and for the practical operation and control of fixed biomass depuration systems.

Thermogravimetry (TG) was used to investigate the pollution on marine sediments close to urban and industrial sites. Sediment weight loss when heated (TG) was performed under oxidizing conditions from 250°C to 900°C. The first derivative of TG curves was used to generate a Cartesian diagram for sediments cataloging, in a quick way, according to their organic matter and grain size contents. Thus, sediment placed at the right of the diagram were characterized by a prevalence of the thin fraction and high organic matter content, while on the left side, samples were characterized by large sandy fractions, and, in general, low organic matter contents. Two references materials and metal pollution index were used to validate the Cartesian diagram obtained.

This paper reports the results of the direct treatment of PCBs sorbed to solid particles (glass beads and sand) employing the Fenton process. The results obtained with contaminated sandy soils show 98% removal of the original PCB structure and 82% dechlorination, all within a reaction time of 72 hours. The degree of removal was observed to be dependent on the level of congener chlorination. The optimized conditions were: 5% H(2)O(2); 100 ppm Fe(3+); sandy soil mass/volume of oxidizing solution ratio (m/V) of 1/3 g/mL, vigorous agitation and dispensed with the need for heat. Results obtained by applying an integrated desorption treatment followed by photo-Fenton oxidation to sandy soils contaminated with PCBs are also present in this paper. Desorption of PCBs with surfactant solutions took place to an extent of around 90% (92.2% with K-perfluoroalkyl sulfonate, FT800, and 87% with Lineal Alkyl benzene Sulfonate, LAS), while photo-Fenton oxidation at 254 nm achieved degradation percentages close to 100% in 30 minutes for PCBs in solution, both with FT800 (98%) and LAS (97%) surfactants.

The Fenton and photo-Fenton mediated degradation process of Orange II was investigated in a flow photo-reactor. The degradation was monitored as a function of the wavelength of the applied light, recirculation flow rate, amount of H2O2 and the initial concentration of Orange II. Optimization of the photo-Fenton degradation mediated by Fe-Nafion membranes indicated that an Orange II (0.25 M) solution discolored above 95% within 2.5 hours at an H2O2/Orange II ratio of 20. A concomitant mineralization of 40% of Orange II was observed after 5 h reaction. Homogeneous photo-Fenton processes were able to fully discolore Orange II within 1 hour and concomitantly fully mineralize the dye in the presence of Fe(III) (2 ppm) and an H2O2/Orange II ratio of 20. Surfactants such as linear alkylbenzene sulphonates (LAS) and K-perfluoroalkyl sulphonate (FT 800) slowed down the Orange II abatement in photo-Fenton processes.

This article proposes a method for the thermogravimetric analysis (TGA) of marine sediment suspected of pollution by heavy metals, which may be appropriate for a selected region where the regression equations relating W2 weight loss as the independent variable and estimated metal abundance as the dependent variable have already been derived. Automated TGA may then be employed as a reconnaissance tool, to give a rapid and inexpensive predictive index of quality. The method has been applied to actual samples of known heavy metal content and the results have been compared with the quality criteria for dredged sediment proposed by the USEPA and other standards. These criteria have been translated into the corresponding classification categories provided by the TGA method. The sediment samples, on which thermal analysis from 50 to 900°C was performed, are from the southwest of Spain and several showed high levels of pollution. The first derivative of TG curves (DTG) and the chemical parameters analyzed were co...

Existen dos modalidades: 1. La VMD que se realiza fundamentalmente durante la noche y que consigue una mejoria de la gasometria arterial durante el dia. En la mayoria de los casos se realiza conectando el ventilador al paciente a traves de una mascarilla nasal (no invasiva). 2. La VMD como continuacion del tratamiento en una unidad de vigilancia intensiva. En este caso la ventilacion debe mantenerse de forma continua o casi continua, por lo que es recomendable una traqueostomia.

A substantial part of the operating costs of wastewater treatment plants (WWTP) is associated with the management and treatment of the excess sludge generated during the treatment process. Different strategies have been applied for excess sludge reduction, such as the oxic-settling-anaerobic process, the high dissolved oxygen process, the uncoupler-containing activated sludge process, the ozonation-combined activated sludge process, control of sludge retention time and biodegradation of sludge in a membrane-assisted reactor. Chemical uncouplers have been shown to reduce excess sludge production, disassociating the energy coupling between catabolism and anabolism. These metabolic uncouplers may be organic compounds, such as 2,4-dinitrophenol (2,4-DNP) or 3,3',4',5-tetrachlorosalicylanilide (TCS), or heavy metals. In this paper, four different chemicals (2,4-DNP, TCS, copper (Cu) and zinc (Zn)) were chosen for short-term tests for studying their ability to reduce sludge yield (Y(x/s)) and, consequently, their potential for reducing excess sludge production. According to the results obtained, only TCS seems to be very effective in reducing sludge production from the activated sludge process. Compared with the control test, Y(x/s) can be reduced by over 30% at 0.8 mg/l TCS. It was also found that the substrate removal capability was not adversely affected by the presence of TCS. Furthermore, an increase in the microbial activity of the system was observed.

Alkyl ethoxysulphates (AES) are anionic surfactants widely used in numerous commercial and industrial applications. In spite of the high AES volume consumption a few data concerning the occurrence, fate and effects of AES in marine environments are reported in literature. The objective of this study is to evaluate the biodegradability and toxicity of AES in pristine sea water. Ultimate biodegradation was studied according to the guideline 835.3160 "Biodegradability in sea water" proposed by the United States Environmental Protection Agency (USEPA). Acute toxicity of AES was studied to the microalgae Nannochloropsis gaditana, Isochrysis galbana, Chaetoceros gracilis, Dunaliella salina and Tetraselmis chuii and the invertebrate Artemia franciscana, using culture growth inhibition and death, respectively, as effect criteria. During the degradative process two different stages were observed, which were better described with the first order and logistic kinetic models, respectively. Lag times were 3.3 (stage A) and 26.5 (stage B) days whereas half-lives were 18.6 (stage A) and 49.8 (stage B) days. AES inhibited the microalgae growth, with 96-h EC50 values ranging from 4.68 g L(-1) for D. salina to 24.02 mg L(-1) for I. galbana. Mean 48- and 72-h LC50 values for A. franciscana were 38.30 and 23.92 mg L(-1), respectively. The results indicate an extensive biodegradability of AES in sea water, although at a very slow rate. Acute toxicity was highly dependent on the species tested, being the green alga D. salina the most affected organism. The present study provides relevant data concerning the biodegradability and adverse effects of an AES surfactant on marine organisms, which are useful to establish water quality criteria in a regulatory framework.

Characterization of organic matter in four sediments in the infuence area of wastewater discharges was carried out by both chemical and thermal analysis in order to assess their pollution level. Oxidisable organic carbon and organic matter were calculated by the standard methodology in laboratory. Thermogravimetry (TG), between 50 and 900 degrees C, was simultaneously performed in oxidizing conditions on ground sediments samples after three different pretreatments. Linear regression adjust of thermal analysis results versus chemical parameters provides the better Pearson's coefficients, leading to the best coefficients for weight loss in 250-400 degree C temperature range versus oxidisable organic carbon and organic matter at 360 degrees C, respectively. These results demonstrated the utility of thermoanalysis technique for the evaluation of the organic matter content of fresh sediments.

The present study describes the effect of the operating variables in the sensitized solar photolysis of sandy sediments contaminated by polychlorinated biphenyls (PCBs) in alkaline isopropanol. PCBs were almost completely removed in two weeks with stoichiometric release of chloride and biphenyl (BP) by a mechanism of reductive dechlorination. The concentration of the sensitizer (acetone) was the variable found to have most influence on the process. Under the same conditions, only partial dechlorination of the PCBs (34%) was observed in dielectric fluids without generating biphenyl to any appreciable extent. Direct photolysis (ultraviolet light at 254nm) of dielectric oils dissolved in alkaline isopropanol lead to 92% removal of PCBs in 60min. The observed mechanism was again that of reductive dechlorination, with stoichiometric release of chloride, and the accumulation of biphenyl, quaterphenyl and condensation products of biphenyl with isopropanol.