Water Quality (Engineering)

This study explores the river-flow-induced impacts on the performance of machine learning models applied for forecasting of water quality parameters in the coastal waters in Hilo Bay, Pacific Ocean. For this purpose, hourly recorded water quality parameters of salinity, temperature and turbidity as well as the flow data of the Wailuku River were used. Several machine learning models including artificial neural network, extreme learning machine and support vector regression have been employed to investigate the river-flow-induced impact on the water quality parameters from the current time up to 2 h ahead. Following the input structure of the machine learning models, two separate models based on including and excluding the river flow were developed for each variable to quantify the importance of the flow discharge on the accuracy of the forecasting models. The performance of different machine learning models was found to be close to each other and showing similar pattern considering accuracy and uncertainty of the forecasts. The results revealed that flow discharge influenced the water salinity and turbidity of the bay in which the models including the river flow as input variables had better performance compared with those excluding the flow time series. Among the water quality parameters investigated in this research, river flow made the most and least improvement on the efficiency of the models applied for forecasting of turbidity and water temperature, respectively. Overall, it was observed that water quality parameters can be properly forecasted up to several hours ahead providing a potentially valuable tool for environmental management and monitoring in coastal areas.

The main aim of the study was to explore the applicability of the one-dimensional (1D) steady state model (QUAL2K) for simulating the water quality in large river. Danube River at lower Danube course was chosen as a case study. The model was calibrated using data on April, 2008 (spring season). Validation of the model was performed using data on September, 2008 (autumn season). Moreover, four different scenarios were examined to control the level of CBOD and DO in the river. The model output revealed that the calibration and validation results were in agreement with the observed values, with some exceptions. Although QUAL2K is one-dimensional steady state model, the simulated results were compatible with previous technical reports. Thus, it can be used as a suitable tool for simulating the water quality in large rivers.

Reclaimed water from small wastewater treatment facilities in the rural areas of the Beira Interior region (Portugal) may constitute an alternative water source for aquifer recharge. A 21-month monitoring period in a constructed wetland treatment system has shown that 21,500 m3 year−1 of treated wastewater
(reclaimed water) could be used for aquifer recharge. A GIS-based multi-criteria analysis was performed, combining ten thematic maps and economic, environmental and technical criteria, in order to produce a suitability map for the location of sites for reclaimed water infiltration. The areas chosen for aquifer
recharge with infiltration basins are mainly composed of anthrosol with more than 1 m deep and fine sand texture, which allows an average infiltration velocity of up to 1 m d−1. These characteristics will provide a final polishing treatment of the reclaimed water after infiltration (soil aquifer treatment (SAT)),
suitable for the removal of the residual load (trace organics, nutrients, heavy metals and pathogens).
The risk of groundwater contamination is low since the water table in the anthrosol areas ranges from 10 m to 50 m. On the other hand, these depths allow a guaranteed unsaturated area suitable for SAT. An area of 13,944 ha was selected for study, but only 1607 ha are suitable for reclaimed water infiltration.
Approximately 1280 m2 were considered enough to set up 4 infiltration basins to work in flooding and
drying cycles.

Solar water disinfection (SODIS) has proven to be effective at reducing diarrheal incidence in epidemiological intervention studies. However, the SODIS method is limited to waters of low turbidity (<30 NTU). This study investigates the use of common table salt (NaCl) to reduce the turbidity of water containing suspended colloidal clay particles for use in the SODIS method. Three representative clays found in tropical soils (kaolinite, illite and bentonite) were tested at three levels of turbidity (50, 100 and 200 NTU) for their flocculating behavior with multiple NaCl concentrations to find the optimum. Supernatants were tested for sodium concentration for comparison against health and taste thresholds. Results show that unlike kaolinite and illite, pure bentonite solutions were shown to be very responsive to NaCl and produced supernatants with as low as 4 NTU (98% particle removal efficiency). This study has shown that NaCl, in combination with high-activity clay particles in solution, may effectively reduce turbidity to levels suitable for SODIS treatment, thereby expanding the number of people who can utilize the technology effectively.

Mounding often occurs beneath engineering structures designed to infiltrate reuse water. AQTESOLV software and a spreadsheet solution for Hantush, together with soil moisture water balance (SWAGMAN farm model), were used for quantitatively predicting the height and extent of groundwater mounding underground to assess the groundwater-flow simulations of infiltration from a hypothetical irrigation site. Horizontal and vertical permeability, aquifer thickness, specific yield, and basin geometry are among the aquifer and recharge properties inputs. For 2.2 ha sites, the maximum heights of the simulated groundwater mound ranges up to 0.29 m. The maximum areal extent of groundwater mounding measured from the edge of the infiltration basins of 0.24 m ranges from 0 to 75 m. Additionally, the simulated height and extent of the groundwater mounding associated with a hypothetical irrigation infiltration basin for 2.2 ha development may be applicable to sites of different sizes, using the recharge rate estimated from the SWAGMAN farm model. For example, for a 2.2 ha site with a 0.0002 m/day recharge rate, the irrigation infiltration basin design capacity (and associated groundwater mound) would be the same as for a 1.1 ha site with a 0.0004 m/day recharge rate if the physical characteristics of the aquifer are unchanged. The study claimed that the present modelling approach overcomes the complications of solving the Hantush equation for transient flow. The approach utilised in this study can be applied for other purposes such as measuring the feasibility of infiltrating water, attenuation zone, risk mitigation essential for decision-makers and planning regulators in terms of environmental effects and water use efficiency.

A strategy for adaptive control and energetic optimization of aerobic fermentors was implemented, with both air flow and agitation speed as manipulated variables. This strategy is separable in its components: control, optimization, estimation. We optimized parameter’s estimation (from the usual KLa correlation) using sinusoidal excitation of air flow and agitation speed. We have implemented parameter’s estimation trough recursive least squares algorithm with forgetting factor. We carried separate essays on control, optimization and estimation algorithms. We carried our essays using an original computational simulation environment, with noise and delay generating facilities for data sampling and filtering.

Our results show the convergence and robustness of the estimation algorithm used, improved with use of both forgetting factor and KLa dead-band facilities. Control algorithm used in our work compares favorably with PID using the integrated area criteria for deviation between oxygen molarity and critical molarity (set point). Optimization algorithm clearly reduces energetic consumption, respecting critical molarity. Integration of control, optimization and adaptive algorithms was implemented, but future work is needed for stability. Methods were defined and implemented for stability improvement. We have implemented data acquisition and computer manipulation of air flow and agitation speed for actual fermentors.

Two bed media were tested (gravel and Filtralite) in shallow horizontal subsurface flow (HSSF) constructed wetlands in order to evaluate the removal of ammonia and nitrate for different types of wastewater (acetate-based and domestic wastewater) and different COD/N ratios. The use of Filtralite allowed both higher mass removal rates (1.1 g NH 4 -N m À2 d À1 and 3 g NO 3 -N m À2 d À1 ) and removal efficiencies (>62% for ammonia, 90-100% for nitrate), in less than 2 weeks, when compared to the ones observed with gravel. The COD/N ratio seems to have no significant influence on nitrate removal and the removal of both ammonia and nitrate seems to have involved not only the conventional pathways of nitrification-denitrification. The nitrogen loading rate of both ammonia (0.8-2.4 g NH 4 -N m À2 d À1 ) and nitrate (0.6-3.2 g NO 3 -N m À2 d À1 ) seem to have influenced the respective removal rates.

In this paper an information management system used in Attica Greece that combines modeling with the integrated management of water, sewerage and storm water infrastructure is presented. From this information management system there are proposed certain public works that are grouped in two categories, i.e. works that are needed for the entire Attica district and have a general character for the whole region (1 st category works) and then, works that are specifically needed for every particular and individual municipality (2 nd category works).

The temporal changes in water quality parameters can be evaluated using multi criteria decision support, which utilizes water quality parameters as different criteria for representing a scenario of water quality parameter variation with time at different zones of the study area of Alandi, Dehu and Chikali near Pune city of Maharashtra state, India. The areas are affected by waterborne diseases including enteric diseases. The temporal variations of water quality parameters in different zones of the study area can act as an indicator regarding the water quality parameter variation related to anthropogenic and other factors. The multi-criteria study quantifies these temporal variations of water quality parameters and can help develop priorities including suggestion for alternative anthropogenic associated activities The multi-criteria evaluation uses pair wise comparison of the water quality parameters to obtain a rating based on the pair wise comparison scale used for numerical rating. The elements of the matrix will present a numerical rating ranging from 1 to 9 depending upon the value of the water quality parameter at a given time. The multi criteria analysis can be carried out using the water quality parameters affecting the health of the people for assessment through multi criteria composite quality index (CQI) covering the different temporal periods.These issues having a bearing on the environmental and ecological changes is brought out in the paper.
Keywords: Water quality; temporal variation; composite quality index (CQI); water pollution.

Nitrogen (N) cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms. Elementary mass balances for COD, DO, NH4-N and alkalinity were conducted and stoichiometric relationships were investigated to explain possible pathways of the nitrogen removal mechanisms in a lab-scale submerged down flow biological packed bed (BPB) reactor. Four sets of experiments were performed by modifying the organic loading and C/N ratio in comparison with steady-state conditions. Approximately 90% of COD and NH4-N removal occurred in two upper sections occupying 1/5 of the reactor height. The elementary
mass balances could not explain all the experimental results with respect to nitrogen removal and oxygen consumption by known mechanisms. The mass balance calculations, excluding the possibility of nitrification, were in general in accordance with the observations indicating no or minimal NO3-N production. The theoretical stoichiometric requirements for nitrification reaction
were satisfied in 6 experiments and in another 8 experiments nitrification may have occurred, but stoichiometry was not satisfied. Using C/N ratio as the variable, only at C/N ratio = 10, the predictions confirmed the possibility of nitrification in the same 3 (out of 4) assays as observed in practice. The results of this study reveal that the nitrogen transformations occurring in the studied reactor are complex and cannot be explained by simple mechanisms of microbial assimilation and nitrification.

Ecosystem services become essential in policy and decision-making since they are part of millennium ecosystem assessment agenda. Catchment area is one of important ecosystems which provide several ecosystem services. Kielstau catchment area is located in northern lowland of Schleswig Holstein, Germany. The scope of study area was delineated based on defining basin area method. It is done by hydrology spatial analyst tools in ArcGis 9.3. Evaluation of ecosystem services in Kielstau mainly adopted from Corine Land Cover classification. Agriculture land (55.76%) and pasture (26.45%) are the dominant land use. Meanwhile, deciduous and evergreen forest occupied small area of total land use. Deciduous forest
provides the largest capacity for ecosystem services and urban area is the lowest. Further analysis on regulating services shows that deciduous forest is considered to have very high capacity to maintain local climate regulation. Agriculture has no
capacity for water quality regulation and contrary with evergreen forest and grassland which provide very high capacity. Evergreen forest also has high relevant capacity to maintain groundwater recharge.

Keyword: ecosystem services, catchment area, Kielstau, local climate, water quality, groundwater recharge, GIS approach.

Solar water disinfection (SODIS) has proven to be effective at reducing diarrheal incidence in epidemiological intervention studies. However, the SODIS method is limited to waters of low turbidity (<30NTU). This study investigates the use of common table salt (NaCl) to reduce the turbidity of water containing suspended colloidal clay particles for use in the SODIS method. Three representative clays found in tropical soils (kaolinite, illite, and bentonite) were tested at three levels of turbidity (50, 100, and 200 NTU) for their flocculating behaviour with multiple NaCl concentrations to find the optimum. Supernatants were tested for sodium concentration for comparison against health and taste thresholds. Results show that unlike kaolinite and illite, pure bentonite solutions were shown to be very responsive to NaCl and produced supernatants with as low as 4 NTU (98% particle removal efficiency). This study has shown that NaCl, in combination with high-activity clay particles in solution, may effectively reduce turbidity to levels suitable for SODIS treatment, thereby expanding the number of people who can utilize the technology effectively.

Low pH soils with insufficient organic matter can benefit from the application of reclaimed water (RW) and biosolids. The presence of nutrients also aids plant growth. This paper presents the results of two integrated research studies, both carried out in the Beira Interior Region (Covilhã, Portugal); one used RW for irrigation, the other applied paper mill sludge to agricultural land. In both cases, multiple criteria based on GIS tools were used for site selection. In the first study, the characteristics of RW analyzed over 2 years were found suitable for crop irrigation. The RW had moderate organic content, low electrical conductivity (CE), high nutrient content (N, P), and low concentrations of nitrate, metals and phytotoxic elements (Al, B, Cl and Na). The multi-criteria analysis was carried out taking into account environmental, technical and economic criteria and a suitable area of 30.5 ha was found for RW irrigation. In the second work, the paper mill sludge was considered suitable for application to agricultural land. Its concentrations of N, P and heavy metals did not a present risk for soil contamination and were suitable for soil improvement and crop production. A multi-criteria analysis based on similar criteria was conducted and a suitable area of 253 ha was found for sludge application.

Most of the wastewater treatment systems in small rural communities of the Cova da Beira region (Portugal) consist of constructed wetlands (CW) with horizontal subsurface flow (HSSF). It is believed that those systems allow the compliance of discharge standards as well as the production of final effluents with suitability for reuse. Results obtained in a nine-month campaign in an HSSF bed pointed out that COD and TSS removal were lower than expected. A discrete sampling also showed that removal of TC, FC and HE was not enough to fulfill international irrigation goals. However, the bed had a very good response to variation of incoming nitrogen loads presenting high removal of nitrogen forms. A good correlation between mass load and mass removal rate was observed for BOD5, COD, TN, NH4-N, TP and TSS, which shows a satisfactory response of the bed to the variable incoming loads. The entrance of excessive loads of organic matter and solids contributed for the decrease of the effective volume for pollutant uptake and therefore, may have negatively influenced the treatment capability. Primary treatment should be improved in order to decrease the variation of incoming organic and solid loads and to improve the removal of COD, solids and pathogenic. The final effluent presented good physical–chemical quality to be reused for irrigation, which is the most likely application in the area.

Ouro Preto county is southeast of Qua-drilatero Ferrifero in the state of Minas Gerais, one of the most known Brazilian mining regions, producing gold, topaz gems and several kinds of iron and manganese ores. However, these activities are the main forms of environmental degradation, affecting the surface and groundwater which is used for public supply and are the source of heavy metal contamination, including mercury and arsenic. The mining and predatory prospecting activity (garim-pos) has been carried out in Minas Gerais since the seventeenth century. At that time, hundreds of placer gold deposits were discovered on the streams in the region of Ouro Preto and Mariana, causing the first big gold rush in Brazilian history. This work presents public supply water quality data from a seasonal cycle, from September 1999 (winter) to February 2000 (summer). Chemical and physical-chemical parameters were assessed with the content of heavy metals. Leaching tests with rock samples to assess contribution to the metal content of water were carried out. Elements in the rocks have been determined and water analysis allowed the hydrog-eochemical classification of water. Leaching tests demonstrate the oxidizing conditions under which the As (and the other elements) is being mobilised to the hydrological system. As and Fe are elements dispersed in the drainage of the regions. This is due to the high amounts of sulfide and to the iron formations of the region.

This research evaluates the effect of both organic and ammonia loading rates and the presence of plants on the removal of chemical oxygen demand and ammonia nitrogen in horizontal subsurface flow constructed wetlands, 2 years after the start-up. Two sets of experiments were carried out in two mesocosms at different organic and ammonia loading rates (the loads were doubled); one without plants (control bed), the other colonized with Phragmites australis. Regardless of the organic loading rate, the organic mass removal rate was improved in the presence of plants (93.4 % higher for the lower loading rate, and 56 % higher for the higher loading rate). Similar results were observed for the ammonia mass removal rate (117 % higher for the lower loading rate, and 61.3 % higher for the higher loading rate). A significant linear relationship was observed between the organic loading rate and the respective removal rates in both beds for loads between 10 and 13 g m -2 day -1 . The presence of plants markedly increase removal of organic matter and ammonia, as a result of the role of roots and rhizomes in providing oxygen for aerobic removal pathways, a higher surface area for the adhesion and development of biofilm and nitrogen uptake by roots.

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1–8 to weeks 9–14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

This research evaluates the effect of both organic and ammonia loading rates and the presence of plants on the removal of chemical oxygen demand and ammonia nitrogen in horizontal subsurface flow constructed wetlands, 2 years after the start-up. Two sets of experiments were carried out in two mesocosms at different organic and ammonia loading rates (the loads were doubled); one without plants (control bed), the other colonized with Phragmites australis. Regardless of the organic loading rate, the organic mass removal rate was improved in the presence of plants (93.4 % higher for the lower loading rate, and 56 % higher for the higher loading rate). Similar results were observed for the ammonia mass removal rate (117 % higher for the lower loading rate, and 61.3 % higher for the higher loading rate). A significant linear relationship was observed between the organic loading rate and the respective removal rates in both beds for loads between 10 and 13 g m -2 day -1 . The presence of plants markedly increase removal of organic matter and ammonia, as a result of the role of roots and rhizomes in providing oxygen for aerobic removal pathways, a higher surface area for the adhesion and development of biofilm and nitrogen uptake by roots.

Similarly to most of Mediterranean EU member states, Portugal regularly experience severe water supply and demand imbalances, particularly in the summer months.
Tourism is a very important economic activity in Portugal and is pushing water demand particularly in regions suffering occasional water deficit, like the southern half part of Portugal mainland. Golf courses are an important tourist factor contributing to water demand rising. A number of golf courses are installed in tourist areas and need high amount of water for irrigation.
Water reuse is a very important management strategy in situations of water scarcity. Portugal badly needs to include treated wastewater as a dependable resource in the nation water resources management. Sustainable water reuse requires technical guidelines to ensure the public health and environmental protection but the economic sustainability is crucial for the success of water reuse projects as a strategy of water conservation. This paper briefly presents Portuguese guidelines on water reuse focusing mainly on the aspects to be taken into account in the assessment of the economic viability of water reuse projects, such as the model of tariff structure, the costs to internalise, share of costs among users and recovery of investment costs.

A new approach on bathing water quality management was given by the New Bathing Water Directive (NBWD), enforcing the implementation of alert and prediction systems in order to avoid bathers exposure to short-term pollution events. This paper focus the study of Portuguese bathing waters located in Estoril Coast, that can be exposed to short term pollution events due to local stream discharges mainly after raining events. An operational model was implemented, using automatic hydrometric stations on streams, monitoring results (streams and coastal waters), and modelling tools (MOHIDWater), to forecast bathing water quality. This model uses a Lagrangian approach to forecast bathing water quality following two criteria: (i) the presence of contamination patches in the bathing water area and (ii) the probability of a bather to be in contact with the contaminated water. This methodology was tested during the 2011 bathing season (May to September), and showed the ability to to predict in time the contamination events identified those bathing waters. The methodology proposed, using a Lagrangian monitor box approach, is able to: i) forecast the risk of having faecal contamination on bathing waters; ii) forecast faecal contamination values, and iii) identify the main pollution sources.
This integrated forecast model is a tool that can be used by local management authorities to answer to NBWD requirements, namely to forecast the bad water quality events and avoid bathers exposure to faecal contaminated waters.

This study explores the river-flow-induced impacts on the performance of machine learning models applied for forecasting of water quality parameters in the coastal waters in Hilo Bay, Pacific Ocean. For this purpose, hourly recorded water quality parameters of salinity, temperature and turbidity as well as the flow data of the Wailuku River were used. Several machine learning models including artificial neural network, extreme learning machine and support vector regression have been employed to investigate the river-flow-induced impact on the water quality parameters from the current time up to 2 h ahead. Following the input structure of the machine learning models, two separate models based on including and excluding the river flow were developed for each variable to quantify the importance of the flow discharge on the accuracy of the forecasting models. The performance of different machine learning models was found to be close to each other and showing similar pattern considering accuracy and uncertainty of the forecasts. The results revealed that flow discharge influenced the water salinity and turbidity of the bay in which the models including the river flow as input variables had better performance compared with those excluding the flow time series. Among the water quality parameters investigated in this research, river flow made the most and least improvement on the efficiency of the models applied for forecasting of turbidity and water temperature, respectively. Overall, it was observed that water quality parameters can be properly forecasted up to several hours ahead providing a potentially valuable tool for environmental management and monitoring in coastal areas.

A new approach on bathing water quality management was given by the New Bathing Water Directive (NBWD), enforcing the implementation of alert and prediction systems in order to avoid bathers exposure to short-term pollution events. This paper focus the study of Portuguese bathing waters located in Estoril Coast, that can be exposed to short term pollution events due to local stream discharges mainly after raining events. An operational model was implemented, using automatic hydrometric stations on streams, monitoring results (streams and coastal waters), and modelling tools (MOHIDWater), to forecast bathing water quality. This model uses a Lagrangian approach to forecast bathing water quality following two criteria: (i) the presence of contamination patches in the bathing water area and (ii) the probability of a bather to be in contact with the contaminated water. This methodology was tested during the 2011 bathing season (May to September), and showed the ability to to predict in time the contamination events identified those bathing waters. The methodology proposed, using a Lagrangian monitor box approach, is able to: i) forecast the risk of having faecal contamination on bathing waters; ii) forecast faecal contamination values, and iii) identify the main pollution sources. This integrated forecast model is a tool that can be used by local management authorities to answer to NBWD requirements, namely to forecast the bad water quality events and avoid bathers exposure to faecal contaminated waters.

Ouro Preto county is southeast of Quadrilatero Ferrifero in the state of Minas Gerais, one of the most known Brazilian mining regions, producing gold, topaz gems and several kinds of iron and manganese ores. However, these activities are the main forms of environmental degradation, affecting the surface and groundwater which is used for public supply and are the source of heavy metal contamination, including mercury and arsenic. The mining and predatory prospecting activity (garimpos) has been carried out in Minas Gerais since the seventeenth century. At that time, hundreds of placer gold deposits were discovered on the streams in the region of Ouro Preto and Mariana, causing the first big gold rush in Brazilian history. This work presents public supply water quality data from a seasonal cycle, from September 1999 (winter) to February 2000 (summer). Chemical and physicalchemical parameters were assessed with the content of heavy metals. Leaching tests with rock samples to assess contribution to the metal content of water were carried out. Elements in the rocks have been determined and water analysis allowed the hydrogeochemical classification of water. Leaching tests demonstrate the oxidizing conditions under which the As (and the other elements) is being mobilised to the hydrological system. As and Fe are elements dispersed in the drainage of the regions. This is due to the high amounts of sulfide and to the iron formations of the region. Keywords Water quality AE Arsenic contamination AE Heavy metals AE Brazil Geology, hydrogeology and climate Ouro Preto Hill (Fig. 1) is in the Quadrilátero Ferrífero region (Almeida 1977). Geological units are (Dorr 1969; Chemale and others 1991): (1) Rio das Velhas greenstone belt, represented by vulcano-sedimentary archean sequence (Nova Lima group schists); (2) Minas supergroup represented by paleoproterozoic metasedimentary units (Moeda formation quartzites, Batatal formation phylites, Cauê formation itabirites and Gandarela formation dolomitic marbles). The region of Ouro Preto is drained by two great basins: the São Francisco basin and the Doce river basin. Ouro Preto Hill is the water dividing chain. According to the Koeppen classification, the climate in Ouro Preto corresponds to the Cwb type. The pluviometry is typical of the tropical regime presenting an average of 1.723.6 mm/ year. The rainy season is from October to March with 89.6% of the annual precipitation. The dry season (from April to September) represents 10.4% of the annual precipitation. The average temperature in Ouro Preto is 18.5°C (Coelho 1994). Methodology Topographical and geological maps of Ouro Preto (SF.23-X-A-III-4) and Mariana (SF.23-X-B-I-3; scale of 1/50,000) were used. The geological maps of São Bartolomeu, Antonio Pereira, Ouro Preto, Santa Rita de Ouro Preto and Mariana (scale of 1/25,000) have also been used and stations for sampling were assigned on these maps (Fig. 2). The sampling of water was carried out in September 1999 (dry season) and in February 2000 (rainy season), according to the climate of the region. Samples were collected at 22 stations (43 samples). The chosen stations

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1-8 to weeks 9 -14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

Content of labile organic matter in surface waters of basin r. Western Bug have been evaluated for biological oxygen demand (BOD5 ). The largest excess of the norm this index for fishery ponds (in 19.0 times) was recorded in 3-t quarter 2015 in the water r. Poltva (v.Kam’yanopil). The reason – an inefficient operation of wastewater treatment facilities in Lviv. On the output from the Lviv region (v. Stargorod) have been observed a slight excess of regulatory indicators of BOD5 level.

Nitrogen (N) cycle involves a complex set of potential biochemical pathways with reactions catalyzed by different microorganisms. Elementary mass balances for COD, DO, NH 4 -N and alkalinity were conducted and stoichiometric relationships were investigated to explain possible pathways of the nitrogen removal mechanisms in a lab-scale submerged down flow biological packed bed (BPB) reactor. Four sets of experiments were performed by modifying the organic loading and C/N ratio in comparison with steady-state conditions. Approximately 90% of COD and NH 4 -N removal occurred in two upper sections occupying 1/5 of the reactor height. The elementary mass balances could not explain all the experimental results with respect to nitrogen removal and oxygen consumption by known mechanisms. The mass balance calculations, excluding the possibility of nitrification, were in general in accordance with the observations indicating no or minimal NO 3 -N production. The theoretical stoichiometric requirements for nitrification reaction were satisfied in 6 experiments and in another 8 experiments nitrification may have occurred, but stoichiometry was not satisfied. Using C/N ratio as the variable, only at C/N ratio = 10, the predictions confirmed the possibility of nitrification in the same 3 (out of 4) assays as observed in practice. The results of this study reveal that the nitrogen transformations occurring in the studied reactor are complex and cannot be explained by simple mechanisms of microbial assimilation and nitrification.

A monitoring campaign in a horizontal subsurface flow constructed wetland under the influence of transient loads of flow-rate, organic matter, nitrogen and suspended solids showed an irregular removal of COD and TSS and lower both removal efficiencies and mass removal rates than the ones observed in other studies for similar operating conditions. This circumstance is associated to the presence of large amount of particulate organic matter from non-point sources. The mass removal rate of ammonia increased 39% as both the water and soil temperatures increased from weeks 1-8 to weeks 9 -14. A good correlation between mass load and mass removal rate was observed for all measured parameters, which attests a satisfactory response of the bed under to transient loads.

The increasing of poisons discharged in water body causes more and more serious harm to the environment. In order to evaluate the whole toxicity of poisonous pollutants in water, it is necessary to use rapid and sensitive analytical methods. Bioassay based on bioluminescent bacteria test is a good and promising method to evaluate toxicity. Comparing to natural bioluminescent bacteria, recombinant bioluminescent bacteria test reveals its advantages in more convenient test condition and higher sensitivity. Constructing different kinds of recombinant bioluminescent bacteria, we can also perform diverse evaluations for various purposes, including specifically identifying type of pollutants and toxicity. The RecA protein of E. coli is involved in important cellular functions such as cell division, recombination-repair, mutagenesis, and phage induction, and recA promoter is among the "strongest" E. coli promoters. In this study, a recombinant plasmid pUCD-recA for genetic toxicity evaluation of environmental pollutants was constructed by fusing the DNA damage-inducible promoter recA to the Vibrio fischeri luxCDABE operon. The PCR analysis and DNA sequencing indicated that the recA promoter had been fused into the multiple cloning site of the promoterless luxCDABE plasmid, pUCD615 and the recombinant for genetic toxicity evaluation of environmental pollutants was constructed successfully. The recombinant bioluminescent strain was named THZH07.

Stream metabolism can be used as a measure of freshwater ecosystem health because of its responsiveness to natural and anthropogenic changes. In this study, we used stream metabolic rates to test for the effects of a timber harvest with Louisiana's current best management practices (BMPs). The study was conducted from 2006 to 2010 in a loblolly pine (Pinus taeda) stand in north-central Louisiana, USA, 45 ha of which was clear cut harvested in the summer of 2007. Dissolved oxygen (DO), water temperature, and stream depth were recorded at a site upstream (serving as a reference) and a site downstream of the harvested area. Using diurnal DO change and an open-system, single-station method at each site, we quantified rates of net ecosystem productivity (NEP), gross primary productivity (GPP), community respiration (CR), and the GPP/CR ratio. The system was predominately heterotrophic, with a GPP/CR ratio of less than one for 82% of the time at the upstream site. No calculated metabolic rate was significantly changed by the

This study was on the technical and biological characteristics of a partial-SHARON submerged-filter bioreactor of 3 L. The main focus was the influence of the hydraulic retention time (HRT) on biofilms. For this purpose, we used molecular tools based on the partial 16S rRNA genes. The results showed that the HRT may affect the nitrification processes of a bioreactor using synthetic
wastewater containing 600 mg/L of ammonia. It was found
that an HRT of 0.5 day transformed 100 % of the ammonium
into nitrite. However, when the HRT was decreased to 0.4 day, there was a significant reduction (35 %) in the quantity of ammonia transformed, which confirmed the complexity of the system operation. Moreover, a PCRTGGE approach highlighted the differences observed. The results obtained showed that an HRT of 0.5 day reduced bacterial biodiversity in the biofilms, which were mainly formed by Nitrosomonas and Diaphorobacter. In contrast, an HRT of 0.4 day facilitated the formation of heterogeneous biofilms formed by nitrifying bacteria, such as Nitrosomonas sp., Nitrosospira sp., and Nitrosovibrio sp.).

Abstract
The paper describes a modelling study of near-shore coastal waters, undertaken to assess the impact of various bacterial input loads on the receiving waters in a coastal basin in the UK. Total and faecal coliforms, used as the indicators for bathing water quality under the European Union (EU) Bathing Water Directive, were numerically modelled using a 2D depth integrated hydro-environmental model. Details are given of the governing equations and solution methods used in the numerical model, together with a discussion of the recent development in faecal bacterial indicator modelling. Details are also given of a field data collection exercise, which involved initially collecting existing information on effluent input loads and followed by an intensive field survey. Using the water quality model, the mortality rate of the pathogen bacteria was investigated. Three methods were used to represent the relationship between the decay rate and the level of solar radiation including: a constant decay rate, day- and night-time decay rates and a solar radiation related time varying decay rate. Relatively close agreement between model predicted and measured total and faecal coliform concentration distributions were obtained for different day- and night-time decay rates and time varying decay rates. No significant differences were found in the optimum decay rates for total and faecal coliform levels. Finally, the impact of the individual inputs on the bathing water quality of the basin was also statistically and numerically investigated. Results showed that the River Irvine was the most significant input during high river flows, and that under these conditions the bathing waters were likely to fail to comply with the European Union Bathing Water Directive. For base river flow conditions the Meadowhead effluent input was found to be critical for both total and faecal coliform level predictions.