Wastewater systems are a structural part of public utilities and as such are vital to the general wellbeing, public health, economic activities and environment protection. These services, with the primary objective of protecting the interests of users, shall be governed by principles of universality of access, continuity and quality of service, efficiency, equity and sustainability of price.
The aim of this paper is to contribute for the improvement of the Portuguese performance assessment system, through the development and application of a complementary methodology to define sectoral and global indices of sanitation service performance in order to evaluate the sustainability of a given wastewater utility. This methodology allows a truly quantitative evaluation in which each performance indicator represents a criterion
to be considered and judiciously weighted. The sectoral indices are calculated as a weighted linear combination of the normalized scores of each performance indicator, which is one of the most common aggregation
procedures available in the context of multicriteria evaluation. The criteria normalization process essentially
based on fuzzy sets defined for each indicator. A sensitivity analysis of indices values to different weighting methods was also performed.; Fundação para a Ciência e a Tecnologia (FCT)
This paper is focused on the application of a biological Sequencing Batch Reactor for the treatment of a complex wastewater discharged by a chemical industry of synthetic glues and resins. The main source of wastewater is the washing and cleaning procedures used in the manufacturing process. The present study comprised the assessment of SBR feasibility as secondary treatment, both at lab and full scale. In the lab scale reactor, at an applied organic load of 0.15 kgCODlkgVSS.day, COD removal was around 65-75% and BOO elimination was higher, 85-90%., The full-scale reactor supported a similar COD and BOO removal efficiency. In both studies, the results confirmed that a fraction of the raw COD was biologically recalcitrant Problems of biomass deflocculation and foaming were observed.
Wastewater treatment is one of the most important
biotechnological processes which are used worldwide to
treat municipal and industrial sewage. Activated-sludge
processes aim to achieve a maximal reduction of the
Biological Oxygen Demand (BOD) of wastewater with
a minimal production of biological solids. Even though
many microbiological methods are available to study
the activated sludge communities, many recent
questions on the role of certain microorganisms are kept
unanswered. A crucial addressed by the present work is
to know if the presence of different groups of bacteria
and protozoa lead to significant consequences on the
process performance. Focusing on the importance of the
interactions between the prokaryotic and the eukaryotic
populations, the work will contribute to the knowledge
of how microbial communities are established in a
complex environment as the activated sludge processes.
Constructed wetlands (CWs) have been recognized as being able to effectively treat
wastewater from municipal and industrial sources. This study focused on the effect of
different substrates and long-term operation of horizontal subsurface flowCWstreating tannery wastewater on the bacterial communities. The CWs were planted with Typha latifolia in
three types of substrate: two units with different types of expanded clay aggregates and one unit with fine gravel. Another unit with expanded clay was left unvegetated. Changes in the bacterial community related to the type of substrate, different hydraulic loading rates and along CW operationwere examined using denaturating gradient gel electrophoresis (DGGE).
Bacterial enumerationwas also performed and several bacterial isolateswere retrieved from
the CWs. Phylogenetic affiliations of those isolates were obtained on the basis of 16S rRNA gene sequences and revealed that they were closely related to the genera Bacillus (TM1S1, TM1R3, TNR1 and TAR1), Paracoccus (TM1R2), Pseudomonas (TM1R1) and Halomonas (TM1S2).
The type of substrate and the presence of T. latifolia had a major effect on the species
richness and the structure of bacterial communities as inferred by numerical analysis of DGGE profiles.
The aim of this study was to investigate the performance of horizontal subsurface flow constructed wetlands planted with Typha latifolia treating tannery wastewater under long-term operation. Two expanded clay aggregates (Filtralite® MR3–8-FMR and Filtralite® NR3–8-FNR) and a fine gravel-FG were used as substrate for the constructed wetland units plus one unit with FMR was left as an unvegetated control. The systems were subject to three hydraulic loadings, 18,8 and 6cm d?¹, and to periods of interruption in the feed. The relationship between the substrate, plant development and removal efficiency, especially of organic matter, was investigated. Organic loadings up to 1800 kg BOD5 ha?¹ d?¹ and 3849 kg COD ha?¹ d?¹ were applied leading to mass removals of up to 652 kg BOD? ha?¹ d?¹ and 1869 kg COD ha?¹ d?¹, respectively. The three different substrates were adequate for the establishment of T. latifolia,
although the clay aggregates allowed for higher plant propagation levels. The units with FNR and FMR achieved significantly higher COD and BOD? removal when compared to the FG and to the unplanted units. The systems proved to be tolerant to high organic loadings and to interruptions in feed suggesting this technology as a viable option for the biological treatment of tannery wastewater.
Wastewaters from leather processing are very complex and lead to water pollution if
discharged untreated, especially due to its high organic loading. In this study the survival of different plant species in subsurface horizontal flow constructed wetlands receiving tannery wastewater was investigated. Five pilot units were vegetated with Canna indica, Typha latifolia, Phragmites australis, Stenotaphrum secundatum and Iris pseudacorus, and a sixth unit was left as an unvegetated control. The treatment performance of the systems under
two different hydraulic loading rates, 3 and 6 cmd1, was assessed. COD was reduced by
41–73% for an inlet organic loading varying between 332 and 1602 kg ha1 d1 and BOD5 was
reduced by 41–58% for an inlet organic loading varying between 218 and 780 kg ha 1 d1. Nutrient removal occurred to lower extents. Phragmites australis and Typha latifolia were the only plants that were able to establish successfully. Despite the high removal of organic content from the influent wastewater, during 17 months of operation, no significant differences in performance were observed between units.
The potential of domestic wastewater treatment plants to contribute for the dissemination of ciprofloxacin-resistant bacteria was assessed. Differences on bacterial counts and percentage of resistance in the raw wastewater could not be explained on basis of the size of the plant or demographic characteristics of population served. In contrast, the treated effluent of the larger plants had significantly more heterotrophs and enterobacteria, including ciprofloxacin-resistant organisms, than the smaller (p
Aerated lagoons are commonly used for domestic and industrial wastewater treatment due to their low cost and minimal need of operational requirements. However, little information is known regarding microbial communities that inhabit these ecosystems. In this study, a 16S-DGGE approach was used to estimate bacterial diversity and to monitor community changes in two aerated lagoons from a wastewater treatment plant receiving urban and industrial effluents. Pronounced shifts between bacterial communities collected in winter–spring and summer–autumn months were detected. Temperature, dissolved oxygen (DO) and pH were the variables that most influenced the bacterial communities. Phylogenetic affiliation of predominant members was assessed by the determination of the 16S rDNA sequence of correspondent bands. Affiliations to Cytophaga–Flexibacter–Bacteroides (CFB) group, Firmicutes, and ?- and ?-proteobacteria were found.
Cork is the outer bark of the cork-tree (Quercus suber L.) and it is a very important industrial sector in western Mediterranean region, being Portugal the
world-leading producer and exporter (1). The anaerobic digestion has never been applied to the treatment and valorization of the industrial cork effluents (cork boiling wastewater, CBW). The goal of the present work is evaluate the role of this biological process in providing valuable biomolecules, i.e. enzymes, during the conversion of CBW. Anaerobic experiments were conducted under mesophilic conditions of temperature and the obtained results suggest that CBW is an interesting substrate to be treated and valorised through the anaerobic digestion. Besides the energy recovery through biogas production by anaerobic digestion of CBW, the increase in the reactor effluent of valuable biomolecules is an aspect of great industrial interest. The identification and characterization of such products of high added value creates a supplementary prospect of effluent valorisation, contributing to the cork sector profits. During the CBW anaerobic digestion process several important alterations on the enzymatic capacity of the digested flow were observed. For instance, the laccase activity contained in the CBW was implemented by anaerobiosis and the xilanase was formed during the process. Laccases exhibit low substrate specificity and can be used in different industrial sectors (i.e. paper manufacturing...
The aim of the present work was the simultaneous treatment of urban wastewater using microalgae and the energetic valorization of the obtained biomass. Chlorella vulgaris (Cv), Scenedesmus obliquus (Sc) and a naturally occurring algal Consortium C (ConsC) were grown in an urban wastewater. The nutrient removals were quite high and the treated water fits the legislation (PT Dec-Lei 236/98) in what concerns the parameters analysed (N, P, COD). After nutrient depletion the microalgae remained two more weeks in the photobioreactor (PBR) under nutritional stress conditions, to induce sugar accumulation (22–43%). The stressed biomass was converted into biohydrogen (bioH2), a clean energy carrier, through dark fermentation by a strain of the bacteria Enterobacter aerogenes. The fermentation kinetics were monitored and fitted to a modified Gompertz model. The highest bioH2 production yield was obtained for S. obliquus (56.8 mL H2/gVS) which was very similar when using the same algae grown in synthetic media.
Laboratories consume great amounts of hazardous chemicals substances and consequently generate wastewater containing them, for example formaldehyde. This substance is widely utilized to preserve biological samples generating many liters of this residue every year. The present work proposes the use of the photo-Fenton process to treat formaldehyde wastewater using sunlight irradiation. Some aspects were investigated such as the iron source, sample and hydrogen peroxide concentration and also the use of stirred systems. The use of ferrioxalate (0.5 mmol L-1) improved the efficiency of the process in relation to the use of iron nitrate, while at least 1.0 mol L-1 H2O2 is necessary to treat the sample of the 500 mg C L-1. Under these conditions, every formaldehyde detectable was degradeted and 89% of the dissolved organic carbon was removed in two hours of exposure to sunlight. These results are satisfaction considerate for São Paulo State Environmental Agency.
The high load of nitrogen present in swine wastewater is one of the biggest management challenges of the activity. The Anammox process emerges as a good alternative for biological removal of nitrogen. This study aims to acclimate sludge collected from swine effluent treatment systems to establish the Anammox process. Two sludge samples were collected at Embrapa Swine and Poultry, Concordia - SC, Brazil, one from the bottom of an inactive anaerobic pond (inoculum A) and another from an aeration tank (inoculum B). Both were acclimated until the depletion of NO3-N, being subsequently inoculated in two reactors (Reactor A - Inoculum A and Reactor B - Inoculum B). The Reactor A showed activity after 110 days of operation, while the Reactor B needed 170 days. The difference in the start-up time could be explained by the different environmental conditions to which each sludge was submitted. FISH and PCR analyses confirmed the presence of microorganisms with Anammox activity, demonstrating that the sludge of swine wastewater treatment systems is a good source of inoculum for the development of the Anammox process.
Metal finishing wastewater containing ions of Zn, Ni, Cu, Fe and Al, as well as of Na and CN- in alkaline pH was treated by electrodialysis. The treatment was conducted in a laboratory cell and in a pilot plant unity. The experiments were carried out using Nafion and Selemion membranes. Results showed most of the metallic ions to have an anionic nature, due to the formation of coordination complexes. Each metallic ion showed a different rate of extraction from the treated solution, depending on the galvanostatic or potentiostatic operation mode. Zn, Ni and Cu have shown higher extraction under galvanostatic control. For Al, higher extraction was observed when the experiment was conducted in a potentiostatic mode. Fe ions exhibited an unexpected behavior, not being removed in the same way as the other ions. The best extraction results were obtained within 2-3 h of treatment.
In 2007, surface waters were collected from 21 sampling points in Barcarena City in Northern Region of Brazil: one sampling point located in a stream that receives discharge of wastewater from a kaolin processing industry and flows into the Curuperê River, three sampling points located near sources that emerge on the left bank and flow into the Curuperê River, nine sampling points in Curuperê River, which flows into the Dendê River, and eight in Dendê River, a tributary on the right bank of the Pará River. For all water samples were quantified 14 physicochemical variables and levels of 12 metals. The results in the points near the sources of the Curuperê River presented physicochemical profile and metal levels which are typical of surface waters being used as reference to compare and identify possible changes in the chemical characteristics of the other sampling points. The comparison between the results obtained for the sources of the Curuperê River and the ones for the point near the discharge of industrial wastewater revealed strong changes in the values of 6 physicochemical variables (pH, electrical conductivity (EC), total dissolved solids (TDS), sulfate (SO4), ammoniacal nitrogen (NH4-N) and salinity) and an increase in magnitude of the levels of four metals (Al...
The anaerobic treatment processes are considered to be well-established methods for the elimination of easily biodegradable organic matter from wastewaters. Some difficulties concerning certain wastewaters are related to the possible presence of dissolved oxygen. The common belief is that anaerobes are oxygen intolerant. Therefore, the common practice is to use sequencing anaerobic and aerobic steps in separate tanks. Enhanced treatment by polishing off the residual biodegradable oxygen demand from effluents of anaerobic reactors, or the biodegradation of recalcitrant wastewater pollutants, usually requires sequenced anaerobic and aerobic bacteria activities. However, the combined activity of both bacteria can also be obtained in a single reactor. Previous experiments with either pure or mixed cultures showed that anaerobes can tolerate oxygen to a certain extent. The oxygen toxicity to methanogens in anaerobic sludges was quantified in batch experiments, as well as in anaerobic reactors. The results showed that methanogens have a high tolerance to oxygen. In practice, it was confirmed that dissolved oxygen does not constitute any detrimental effect on reactor treatment performance. This means that the coexistence of anaerobic and aerobic bacteria in one single reactor is feasible and increases the potentials of new applications in wastewater treatment
Wastewater treatment plants (WWTP) are complex systems that incorporate a large number of biological, physicochemical and biochemical processes. They are large and nonlinear systems subject to great disturbances in incoming loads. The primary goal of a WWTP is to reduce pollutants and the second goal is disturbance rejection, in order to obtain good effluent quality. Modeling and computer simulations are key tools in the achievement of these two goals. They are essential to describe, predict and control the complicated interactions of the processes. Numerous control techniques (algorithms) and control strategies (structures) have been suggested to regulate WWTP; however, it is difficult to make a discerning performance evaluation due to the nonuniformity of the simulated plants used. The main objective of this paper is to present a benchmark of an entire biological wastewater treatment plant in order to evaluate, through simulations, different control techniques. This benchmark plays the role of an activated sludge process used for removal of organic matter and nitrogen from domestic effluents. The development of this simulator is based on models widely accepted by the international community and is implemented in Matlab/Simulink (The MathWorks...
Oxidation processes can be used to treat industrial wastewater containing non-biodegradable organic compounds. However, the presence of dissolved salts may inhibit or retard the treatment process. In this study, wastewater desalination by electrodialysis (ED) associated with an advanced oxidation process (photo-Fenton) was applied to an aqueous NaCl solution containing phenol. The influence of process variables on the demineralization factor was investigated for ED in pilot scale and a correlation was obtained between the phenol, salt and water fluxes with the driving force. The oxidation process was investigated in a laboratory batch reactor and a model based on artificial neural networks was developed by fitting the experimental data describing the reaction rate as a function of the input variables. With the experimental parameters of both processes, a dynamic model was developed for ED and a continuous model, using a plug flow reactor approach, for the oxidation process. Finally, the hybrid model simulation could validate different scenarios of the integrated system and can be used for process optimization.
High water consumption and water scarcity make industrial wastewater reuse necessary, especially in those industries characterized by polluted effluents such as welding electrode manufacturing industries. The present paper investigates the coupling of coagulation-flocculation with nanofiltration (NF) to recycle water and reuse it in the process. First, the effect of different concentrations of a mixture of alum (Al2(SO4)3.18H2O) and ferric chloride (FeCl3) on the pretreatment process was closely studied. Then the NF process was applied for complementary treatment. The NF results show that, by increasing both flow rate and transmembrane pressure (TMP), permeate flux is increased. The NF results also show that the COD value decreases below 2 mg/l, TDS rejection approaches 82%, turbidity decreases below 1 NTU and the hardness is lower than the factory constraint (100 mg/l as CaCO3), allowing the reuse of the treated wastewater in the process.
Among the food industries, the dairy industry is considered to be the most polluting one because of the large volume of wastewater generated and its high organic load. In this study, an aerobic membrane bioreactor (MBR) was used for the treatment of wastewater from a large dairy industry and two hydraulic retention times (HRT), 6 and 8 hours, were evaluated. For both HRTs removal efficiencies of organic matter of 99% were obtained. Despite high permeate flux (27.5 L/h.m²), the system operated fairly stablely. The molecular weight distribution of feed, permeate and mixed liquor showed that only the low molecular weight fraction is efficiently degraded by biomass and that the membrane has an essential role in producing a permeate of excellent quality.
In this work, the performance of a sequencing batch reactor (SBR) on aerobic granular sludge was studied for urban wastewater treatment. The system was inoculated with aerobic activated sludge collected from a wastewater treatment plant and, after 30 days of operation, the first granules observed had an average diameter of 0.1 mm. The biomass concentration reached a maximum value around 4 g VSS L-1, and COD removal and nitrification efficiency achieved stable values of 90%. The predominant oxidizing ammonium bacteria in the granules were identified as Nitrosomonas spp.