Energy efficiency in membrane bioreactors.

Energy consumption remains the key factor for the optimisation of the performance of membrane bioreactors (MBRs). This paper presents the results of the detailed energy audits of six full-scale MBRs operated by Suez Environnement in France, Spain and the USA based on on-site energy measurement and analysis of plant operation parameters and treatment performance. Specific energy consumption is compared for two different MBR configurations (flat sheet and hollow fibre membranes) and for plants with different design, loads and operation parameters. The aim of this project was to understand how the energy is consumed in MBR facilities and under which operating conditions, in order to finally provide guidelines and recommended practices for optimisation of MBR operation and design to reduce energy consumption and environmental impacts.

The role of MBR technology for the improvement of environmental footprint of wastewater treatment.

This paper aims to demonstrate the relevance of membrane bioreactor (MBR) technology for the reduction of the environmental footprint of wastewater treatment in terms of removal of microbial and organic trace pollutants with increased reliability of operation. The application of a holistic approach using failure mode analysis, life cycle analysis (LCA), water quality fingerprints and environmental impacts underlines the lower environmental footprint of MBRs compared with conventional activated sludge. Several elements of this empirical approach can be included to upgrade the existing LCA tools in order to include the reduction of eco-toxicity, better human health protection and water reuse.

On-site evaluation of the removal of 100 micro-pollutants through advanced wastewater treatment processes for reuse applications.

The next challenge of wastewater treatment is to reliably remove micro-pollutants at the microgram per litre range in order to meet reuse applications and contribute to reach the good status of the water bodies. A hundred priority and relevant emerging substances were measured to evaluate at full-scale the removal efficiencies of seven advanced treatment lines (one membrane bioreactor process and six tertiary treatment lines) that were designed for reuse applications. To reliably compare the processes, specific procedures for micro-pollutants were applied for sampling, analysis and calculation of removal efficiencies. The membrane bioreactor process allowed to upgrade the removal efficiencies of about 20% of the substances measured, especially those that were partially degraded during conventional processes. Conventional tertiary processes like high rate clarification, sand filtration and polishing pond achieved significant removal for some micro-pollutants, especially for adsorbable substances. Advanced tertiary processes, like ozonation, activated carbon and reverse osmosis were all very efficient to complete the removal of polar pesticides and pharmaceuticals; metals and less polar substances were better retained by reverse osmosis.

Impaired microvascular reactivity and endothelial function in patients with Cushing's syndrome: influence of arterial hypertension.

The aim of the study was to evaluate skin microvascular reactivity (MVR) and possible influencing factors (fibrinolysis, oxidative stress, and endothelial function) in patients with Cushing's syndrome. Twenty-nine patients with active Cushing's syndrome (ten of them also examined after a successful operation) and 16 control subjects were studied. Skin MVR was measured by laser Doppler flowmetry during post-occlusive (PORH) and thermal hyperemia (TH). Malondialdehyde and Cu,Zn-superoxide dismutase were used as markers of oxidative stress. Fibrinolysis was estimated by tissue plasminogen activator (tPA) and its inhibitor (PAI-1). N-acetyl-beta-glucosaminidase, E-selectin, P-selectin, and ICAM-1 were used as markers of endothelial function. Oxidative stress and endothelial dysfunction was present in patients with hypercortisolism, however, increased concentration of ICAM-1 was also found in patients after the operation as compared to controls (290.8+/-74.2 vs. 210.9+/-56.3 ng.ml(-1), p<0.05). Maximal perfusion was significantly lower in patients with arterial hypertension during PORH and TH (36.3+/-13.0 vs. 63.3+/-32.4 PU, p<0.01, and 90.4+/-36.6 vs. 159.2+/-95.3 PU, p<0.05, respectively) and similarly the velocity of perfusion increase during PORH and TH was lower (3.2+/-1.5 vs. 5.2+/-3.4 PU.s(-1), p<0.05, and 0.95+/-0.6 vs. 1.8+/-1.1 PU.s(-1), p<0.05, respectively). The most pronounced impairment of microvascular reactivity was present in patients with combination of arterial hypertension and diabetes mellitus.

Technical and sanitary aspects of wastewater disinfection by UV irradiation for landscape irrigation.

Water reuse for landscape irrigation requires the production of high quality virus-free effluents to minimize risk for human health. In order to establish the relevance of MS2 phages as an appropriate biodosimeter for UV design, a pilot plant study has been carried out with different types of wastewater effluents. The two pilot systems tested (low-pressure high output and medium-pressure UV units) were able to achieve 4 and 5 log MS2 reduction in tertiary filtered effluent at high calculated UV doses of 170 _ 10 and 300 mJ/cm2, respectively. UV disinfection was extremely efficient for MS2 inactivation in high quality effluents after reverse osmosis: detention times as low as one second and UV dose of 40 mJ/cm2 were sufficient to reach 5 log inactivation of MS2. UV irradiation also produced rapid inactivation of human pathogens such as poliovirus type 1 and indigenous enteroviruses at UV doses up to 3 times lower that those for MS2 disinfection. It was concluded that accurate UV unit design for a given type of wastewater could be ensured by pilot tests using laboratory-propagated MS2 as biodosimeter and collimated-beam tests as the calibration-check.

Mixing and its impact on faecal coliform removal in a stabilisation pond.

Faecal coliform removal in stabilisation ponds is highly dependent on shortest water retention times. Tracer tests have been performed in a 3,300 m2 and 1.0 m deep pond, located in Southern France, to measure the retention times and bring light on the main influencing factors and mechanisms. Tracer concentrations were monitored at the outlet and 60 locations within the pond--at the surface, mid depth and the bottom of the water column. Pond water temperatures were measured at different depths and locations, together with pH, DO and redox potential. Wind velocity and rainfall were recorded. Water quality was monitored at the inlet, outlet and within the pond. Water retention times were shown to be strongly affected by weather conditions. Windy periods appeared to favour mixing regardless of the season. In sunny periods of spring and summer, a clear stratification was observed during daytime and vanished gradually during the night, suggesting alternation of mixed and stratified hydrodynamic patterns. This alternation was shown to influence microorganism contents within and at the outlet of the pond. Accurate prediction of shortest water retention times and disinfection performance requires 3D unsteady state fluid dynamic models that are able to take the influence of wind and water temperature distribution into account.

Design of a climate-dependent water reuse project.

Reclaimed water storage is imperative in water reuse management. Climate is a primary factor controlling reclaimed water storage design by its significant influence on irrigation water needs as well as on stored water quality. This study presents a modelling approach that has been applied to assist the design of a climate-dependent water reuse project on an Atlantic island. Models for predicting irrigation water needs and water quality in tertiary lagoons were coupled with a technical-economic model to design reclaimed water storage facilities. Three scenarios corresponding to different augmentation of current reclaimed water reuse were investigated. According to the modelling, the storage sizes to meet the water quantity required for irrigation increased with water deficit--the difference between evapotranspiration and precipitation. The size of tertiary lagoons to meet required water quality was found to be larger than the size to meet required water quantity. To meet both quantitative irrigation needs and <1,000 FC/100 ml irrigation and disposal regulation, extending the tertiary lagoon system would be more cost-effective than storage calculated to meet only quantitative irrigation needs supplemented with UV disinfection. The reliability of reclaimed water storage design was estimated with 40 years historic climatic records.

Wastewater disinfection by low-pressure UV and ozone: a design approach based on water quality.

Disinfection processes are known to be very sensitive to wastewater quality. This paper discusses the parameters that impact the UV light (UV) and ozone disinfection processes and the related mechanisms based on literature review. Low-pressure UV and ozone technologies were investigated on effluents that covered a wide range of water quality. The results are given in terms of design doses required to meet three major disinfection standards. Both processes were found eligible for the majority of effluents tested. Although cost-effectiveness is usually considered more favourable to UV, the ozone alternative should be examined in cases such as the disinfection of low-quality effluents or large treatment plants. Ozonation was also found capable of meeting the stringent Title 22 standard with no coagulation at a dose of 10 mg/l.

Water quality assessment for indirect potable reuse: a new methodology for controlling trace organic compounds at the West Basin Water Recycling Plant (California, USA).

The West Basin Water Recycling plant (California; USA) was built to increase the region's water resource availability. The plant influent is produced at Los Angeles Hyperion wastewater treatment plant and is treated through two parallel treatment processes depending on the end use: (1) Title 22 water for industrial and urban use, and (2) barrier treatment for groundwater recharge. A new methodology was applied to monitor the fate of base neutral compounds in the water barrier treatment train. The methodology included large sample volumes coupled with integrated chromatographic analysis (ICA). Data indicated a 25% increase in concentration of base neutral compounds after RO pretreatment, followed by a 70% removal efficiency after RO. The increase in concentration after RO pretreatment appears to be linked to the use of lime clarification.

Role of water reuse for enhancing integrated water management in Europe and Mediterranean countries.

Recycling water is an important aspect of water resource and environment management policies, ensuring reliable alternative water resources, reducing environmental pollution and achieving a more sustainable form of development. This paper focuses on wastewater reuse as a strategy for integrated water management. Key economic, financial, regulatory, social and technical factors that help to make water reuse projects successful are reviewed. Selected examples from Northern and Western Europe and arid and semi-arid Mediterranean regions illustrate the contribution of wastewater reuse to integrated management of water resources.

Technical-economic modelling of integrated water management: wastewater reuse in a French island.

An integrated technical-economic model is used to address water management issues in the French island of Noirmoutier. The model simulates potable water production and supply, potable and non potable water demand and consumption, wastewater collection, treatment and disposal, water storage, transportation and reuse. A variety of water management scenarios is assessed through technical, economic and environmental evaluation. The scenarios include wastewater reclamation and reuse for agricultural and landscape irrigation as well as domestic non potable application, desalination of seawater and brackish groundwater for potable water supply. The study shows that, in Noirmoutier, wastewater reclamation and reuse for crop irrigation is the most cost-effective solution to the lack of water resources and the protection of sensitive environment. Some water management projects which are regarded as having less economic benefit in the short-term may become competitive in the future, as a result of tightened environmental policy, changed public attitudes and advanced water treatment technologies. The model provides an appropriate tool for water resources planning and management.

Disinfection of urban wastewaters by ozone: a new efficient alternative solution

El trabajo presenta los resultados de estudios pilotos para la desinfeccion de aguas residuales en la Argentina, Inglaterra y Francia. Se demuestra que la ozonozacion pueden implementarse en diferentes pasos del tratamiento de acuerdo con las regulaciones vigentes: en caso de requerimientos menos exigentes se recomienda la desinfeccion de los efluentes primarios y secundarios, mientras que para la desinfeccion total es necesario el tratamiento terciario avanzado

Human hybridomas secreting monoclonal antitreponemal antibodies raised after in vitro stimulation of human lymphocytes.

Peripheral blood lymphocytes from patients with syphilis were stimulated in vitro against Treponema pallidum extract and consequently were fused with mouse myeloma cells to raise heterohybridomas secreting specific human antibodies. In these experiments, 5 heterohybridomas were selected which were shown to secrete monoclonal antibodies which recognized treponemal antigens. Some of the monoclonal (Mab 1C12, Mab 1D11) react with antigens specific to T. pallidum while others (Mab 2A2, Mab 2C8, Mab 2C11) bind to treponemal components which demonstrated group specificity.

[Leukocyte alkaline phosphatase in acute, chronic and exacerbated cholecystitis complicated and uncomplicated by cholelithiasis]. / Levkotsitna alkalna fosfataza pri ostri, khronichni izostreni kholetsistiti, uslozhnena i neuslozhnena kholelitiaza.

The leukocyte alkaline phosphatase was determined in 101 patients with acute and chronic exacerbated cholecystitis, complicated and non-complicated cholelithiasis. Enhanced enzyme activity was established in the inflammatory diseases of the gallbladder and biliary ducts, that was normalized with the effective treatment. No essential alterations were established in case of non-complicated cholelithiasis.

[Cytochemical study of glycogen in the leukocytes in viral hepatitis]. / Tsitokhimichno izsledvane na glikogen v levkotsiti pri virusen khepatit.

Glycogen in 70 patients with viral hepatitis was cytochemically established. Its content proved to be increased, not directly associated with the severity of the disease. The corticoid treatment applied had no essential effect on glycogen content.

[Cytochemical study of glycogen and peroxidase in acute and chronic exacerbated cholecystitis uncomplicated and complicated by cholelithiasis]. / Tsitokhimichno izsledvane na glikogen i peroksidaza pri ostri, khronichni izostreni kholetsistiti, uslozhnena i neuslozhnena kholelitiaza.

Glycogen content and peroxidase activity in 101 patients with acute, chronic exacerbated cholecystitis and noncomplicated cholelithiasis were investigated. An increase of the indices was established in case of inflammatory diseases of gallbladder and biliary ducts, being parallel to the severity of the pathological process. The values were normalized with the successful treatment. No essential deviations from the normal values were found in the non-complicated cholelithiasis.

[Leukocyte alkaline phosphatase in epidemic hepatitis]. / Levkotsitna alkalna fosfataza pri epidemichen khepatit.

The carried out investigations on 70 patients with epidemic hepatitis, 52 of them treated with prednisolon and 18-symptomatically revealed the following: the normal alkaline phosphatase, established prior to the treatment, was elevated with the applied prednisolon treatment and showed no significant alteration in the patients without cortico-therapy. No correlation was found between leukocyte alkaline phosphatase and serum alkaline phosphatase transaminase, serum bilirubin and thymol test. No relationship was found between the severity of the ailment course and the leukocyte alkaline phosphatase.