Naegleria. fowleri, a protozoa belonging to the free-living amoeba group, is the causative agent of a central nervous system affecting disease that is fatal in more than the 95% of the reported cases. This parasite can be found in warm water bodies such as lakes, rivers or inadequately disinfected swimming pools. On the other hand, chlorination and UV light treatment are two of the most extensively used disinfection methods in recreational water facilities. In this study the effect of chlorination and UV light on N. fowleri trophozoites was studied in a close water circuit with the aim to assess the efficacy of this disinfection methods in large pools. The obtained results showed that the chlorination was able to decrease the number of viable cells despite the elimination was not totally achieved. Nonetheless, the combination of the UV light with the chlorination allowed the complete removal of the N. fowleri trophozoites from the water in experimental testing conditions.

Microalgae biotechnology is of increasing importance and a central application concerns the treatment of wastewater. Here, its implementation in a recirculating aquaculture system (RAS) to lower the discharge of wastewater is studied. To better cope with external variations in culture conditions, a co-cultivation of two species of microalgae, Chlorella vulgaris and Tetradesmus obliquus, was used to obtain a more reliable and robust culture and was compared to monocultures. This approach was tested using RAS water both under sterile and non-sterile conditions at laboratory scale and then compared to a co-culture at pilot-scale in an open thin-layer photobioreactor. Performance of cultures was tested in terms of microalgae growth and nutrient removal efficiency. Furthermore, to better understand the interaction between environmental variables and each microalgae species, their relative frequencies in co-cultures as well as the presence of protozoa and bacteria were monitored. All growth experiments were carried out successfully and, unlike in a previous study, no crashes were observed. However, shifts in species frequency in co-cultures indicated that the two species were differentially affected by cultivation conditions. Despite nutrient limitation, the pilot-scale cultivation had a high productivity (13.3¿g¿m¿2 d¿1) and final dry weight (11.1¿g¿l¿1) after 29¿days and demonstrated its suitability for RAS water treatment.

The artisan production of canned tuna is characterized by generating effluents with high organic and saline loads, which complicates their suitable treatment. The main objective of the LIFE VERTALIM project is to demonstrate the efficiency of a holistic solution (including technical, legislative, social, and environmental aspects) for the controlled integration of food industry wastewater from small and medium enterprises (SMEs) in the urban sanitation system with the compliance of all stakeholders. This work shows the viability of the implementation of low-cost innovative solutions, through the clean and eco-efficient production and wastewater pretreatment for fish canneries. This solution allows on average a reduction of 30% of the wastewater discharges to the environment and a reduction of food losses of up to 0.1%. Moreover, there is a reduction of between 40% and 90% related to high organic load. These results allow the canneries to dispose their pretreated effluents to the urban sanitation system, avoiding the high costs of an industrial wastewater treatment plant (WWTP) to discharge to the river. A better physical-chemical quality in the river waters as a well as the marine water surrounding the urban WWTP have been achieved.

The ongoing and increasing worldwide demand for fish has caused a steady increase in aquaculture production during the last decades. This emphasizes the importance of farming systems with a low ecological footprint, like recirculating aquaculture systems (RAS), which are an alternative to traditional open systems. Furthermore, implementing microalgae treatments in RAS, sustainable water management and low discharge of concentrated wastewater could be achieved, allowing its reuse in the system. The influence of three factors on microalgae treatment efficiency in RAS water were studied: i) microalgae species (Chlorella vulgaris, Tetradesmus obliquus), ii) water pre-treatment (sterile filtration), and iii) sampling location within the RAS (e.g. from fish tank, after UV-disinfection, etc.). To this end, fully factorial, replicated cultivations were carried out in 100-ml flasks, and nutrient removal, microalgae growth, and density of bacteria and protozoa were measured for up to 18 days. Results show that both species are able to grow in RAS water and effectively remove nutrients in it, yet their performance depended greatly on water quality. In sterile RAS water, growth and nutrient removal efficiency of C. vulgaris surpassed that of T. obliquus. In non-sterile RAS water, the pattern reversed because of grazing protozoa. The location of sampling within the RAS had no discernible effect on microalgae growth or nutrient removal efficiency. The results confirm that a microalgae-based technology to treat and valorise RAS water is technically feasible, yet caution that inferences made can be reversed depending on the choice of the species and the pretreatment of the RAS water prior to cultivation.

The pilot-scale high-solids anaerobic digestion (HS-AD) of agro-industrial wastes and sewage sludge was analysed in terms of stability by monitoring the most common parameters used to check the performance of anaerobic digesters, i.e. Volatile Fatty Acids (VFA), ammonia nitrogen, pH, alkalinity and methane production. The results reflected similar evolution for the parameters analysed, except for an experiment that presented an unsuccessful start-up. The rest of the experiments ran successfully, although the threshold values proposed in the literature for the detection of an imbalance in wet processes were exceeded, proving the versatility of HS-AD to treat different wastes. The results evidence the need for understanding the dynamics of a high-solids system so as to detect periods of imbalance and to determine inhibitory levels for different compounds formed during anaerobic decomposition. Moreover, the findings presented here could be useful in developing an experimental basis to construct new control strategies for HS-AD. (C) 2013 Elsevier Ltd. All rights reserved.

The combination of simulation studies and expert knowledge allows the development of a decision tree for the integrated operation of nutrient removal as well as filtration processes in membrane bioreactors (MBRs). In order to do it, a model-based methodology, including model development and use of system analysis tools, was followed to identify the best operational strategies for good filtration performance and efficient biological nutrient removal at lower costs in a University Cape Town (UCT)-MBR pilot plant. Activated sludge no. 2 and a series resistance model were used to simulate the biological and filtration processes, respectively. A sensitivity analysis was carried out for the identification of the most sensitive operational parameters, and then, their best setpoint ranges/values were identified through a scenario analysis. Simulation results were supplemented with expert process knowledge to overcome the current limitations of biological and filtration models. The results were organized in the form of a decision tree. The most sensitive parameters, and thus the first branch to explore, were operational parameters related to the filtration processes (i.e. flux and relaxation time). Based on expert knowledge, membrane-air scour was the following control action to check. Then, the decision tree evaluates the biological nutrient removal processes and modifies the necessary operational parameters, ranked according to their sensitivity. The most sensitive were aerobic and membrane aeration, aerobic and anoxic recirculations and carbon dosage. The last branch takes into account the operational cost, directly related to aeration and carbon addition. (C) 2012 Elsevier B.V. All rights reserved.

The viability of the anaerobic membrane bioreactor (AnMBR) technology for the treatment of sewage sludge has been studied under mesophilic and thermophilic conditions. Coupling membrane filtration with the digestion process allows the digestion to be operated with longer solids retention time (SRT), and the volumetric load can be increased considerably compared to the conventional completely stirred reactor process. Maximum SRT is conditioned by the total solids concentration and the viscosity of the digested sludge. Values of 50 and 30 days for 55 and 35 degrees C were obtained in the experimental platforms. Organic loads of 64 and 4.6 gCOD/(L-d) were successfully treated at 55 and 35 degrees C, respectively, representing a significant digester volume reduction compared to conventional systems. The performance of thermophilic and mesophilic AnMBRs were compared, and the same sludge biodegradability was measured. The difference was the distribution of the inert COD among the soluble and particulate fractions. Better filtration performance was observed in the thermophilic system, where a larger flow could be attained and the lower viscosity enabled operation with higher SRT. However, increased irreversible fouling at higher temperature was shown to require optimised chemical cleaning strategies to extend membrane lifetime. In conclusion, AnMBR offers an extensive opportunity for the treatment of waste streams with high solids content waste streams, where membrane filtration is one of the most promising technologies for decoupling solids and hydraulic retention times. (C) 2013 Elsevier B.V. All rights reserved

The increasing costs associated with water supply and the disposal of wastewater has stimulated industries to seek more efficient water management systems. Mathematical modelling and simulation can be a very valuable tool for the study of the multiple alternatives available whilst assessing optimum solutions for water management in industry. This study introduces a new steady state model library able to reproduce industrial water circuits. It has been implemented in a novel software framework for the representation, simulation and optimization of industrial water networks. A water circuit representing a paper mill has been modelled and simulated showing the capability to reproduce real case studies. Alternative scenarios for the water network have also been tested to assess the capability of the models to optimize water circuits minimizing total cost.

Although membrane bioreactors (MBRs) technology is still a growing sector, its progressive implementation all over the world, together with great technical achievements, has allowed it to reach a mature degree, just comparable to other more conventional wastewater treatment technologies. With current energy requirements around 0.6-1.1 kWh/m(3) of treated wastewater and investment costs similar to conventional treatment plants, main market niche for MBRs can be areas with very high restrictive discharge limits, where treatment plants have to be compact or where water reuse is necessary. Operational costs are higher than for conventional treatments; consequently there is still a need and possibilities for energy saving and optimisation. This paper presents the development of a knowledge-based decision support system (DSS) for the integrated operation and remote control of the biological and physical (filtration and backwashing or relaxation) processes in MBRs. The core of the DSS is a knowledge-based control module for air-scour consumption automation and energy consumption minimisation.

MBR technology is currently challenging traditional wastewater treatment systems and is increasingly selected for WWTP upgrading. MBR systems typically are constructed on a smaller footprint, and provide superior treated water quality. However, the main drawback of MBR technology is that the permeability of membranes declines during filtration due to membrane fouling, which for a large part causes the high aeration requirements of an MBR to counteract this fouling phenomenon. Due to the complex and still unknown mechanisms of membrane fouling it is neither possible to describe clearly its development by means of a deterministic model, nor to control it with a purely mathematical law. Consequently the majority of MBR applications are controlled in an "open-loop" way i.e. with predefined and fixed air scour and filtration/relaxation or backwashing cycles, and scheduled inline or offline chemical cleaning as a preventive measure, without taking into account the real needs of membrane cleaning based on its filtration performance. However, existing theoretical and empirical knowledge about potential cause-effect relations between a number of factors (influent characteristics, biomass characteristics and operational conditions) and MBR operation can be used to build a knowledge-based decision support system (KB-DSS) for the automatic control of MBRs. This KB-DSS contains a knowledge-based control module, which, based on real time comparison of the current permeability trend with "reference trends", aims at optimizing the operation and energy costs and decreasing fouling rates. In practice the automatic control system proposed regulates the set points of the key operational variables controlled in MBR systems (permeate flux, relaxation and backwash times, backwash flows and times, aeration flow rates, chemical cleaning frequency, waste sludge flow rate and recycle flow rates) and identifies its optimal value. This paper describes the concepts and the 3-level architecture of the knowledge-based DSS and details the knowledge-based control module. Preliminary results of the application of the control module to regulate the air flow rate of an MBR working with variable flux demonstrates the usefulness of this approach.

his work presents a global model of sanitation system that integrates different simulation tools. The main objective of this work is to manage, in a controlled way, high salinity industrial discharges to ensure the stability of the sewer network and the municipally wastewater treatment plant.