Performance of constructed evaporation ponds for disposal of smelter waste water: a case study at Portland Aluminum, Victoria, Australia

The construction of evaporative ponds and wetlands for the disposal of waste water high in ionic concentrations is a waste disposal strategy currently considered by many industries. However, the design, construction and management of these ponds and wetlands are not straightforward as complex chemical interactions result in both spatial and temporal changes in water quality. The effects of evaporation and drainage on the water quality in two constructed ponds, an adjacent man-made wetland and local groundwater at Portland Aluminium were investigated. The minimum volume of water entering the ponds during the study period was 0.96 +/- 0.16 ML per month. The predicted theoretical evaporative capacity of the two ponds was calculated to be 0.30 +/- 0.07 ML per month. More water enters the ponds than it is theoretically possible to evaporate under the ambient weather conditions at Portland, yet the ponds do not overflow, suggesting percolation through the pond lining. No spatial differences in solute concentrations (fluoride, sulphate, bicarbonate, carbonate, sodium, potassium, calcium, and magnesium ions) were found within the waters of either pond, although temporal differences were apparent. The results support the conclusion that the ponds are not impermeable, and that much of the waste water entering the ponds is being lost through seepage. The impacts on local groundwater chemistry of this seepage are addressed. Significant correlations exist between solute presence within and between the ponds. wetland and groundwater. Fluoride and sulphate concentrations were significantly higher in pond waters throughout the duration of the experiment. Pond sediments revealed a high degree of spatial and temporal heterogeneity in the concentration of all monitored ions resulting from the chemical heterogeneity of the material making up the pond linings. Adsorption isotherms for fluoride indicate that the adsorption capacity of the pond linings remains high for this ion. Implications for the management of waste water by this strategy are discussed.     

Analysis of microbiota in rhizosphere,water and gut of grass carp (Ctenopharyngodon idella) in ponds treated with artificial floating beds

With the increasing demand for environment friendly aquaculture, artificial floating beds have been now widely applied. However, there are few data available on the effect on microbiota in ponds. This study assessed the rhizobacteria community of artificial floating beds with three different kinds of aquatic plants [water spinach (Ipomoea aquatic), water hyacinth (Eichhornia crassipes) and alligator weed (Alternanthera philoxeroides)]. We used Polymerase Chain Reaction‐Denaturing Gradient Gel Electrophoresis to assess whether artificial floating beds would result in changes in microbiota of pond water and gut of grass carp (Ctenopharyngodon idella). The results showed that there existed no significant differences in rhizobacterial composition, and artificial floating beds would not greatly affect the microbiota of pond water. The dominant microbiota in the guts of grass carp changed from Aeromonas jandaei to Paenibacillus sp. Our results indicated that artificial floating beds may serve as a candidate of modulating fish gut microbiota.     

稳定塘用于石化废水尾水处理的中试研究

分别构建了自然型和人工型2种稳定塘的中试系统,探索稳定塘用于石化废水尾水处理的效果以及人工强化措施对稳定塘功能的影响.结果表明,在地广人稀的西部地区选择适宜的场地建设稳定塘作为石化废水达标排放(或回用)前的防护性终端处理单元,具有兼顾进一步净化水质和调节性存贮的双重功效.自然型和人工型稳定塘具有各自不同的功能优势.自然型稳定塘对氮、磷的去除效果略优,对氨氮和TP的质量去除率分别为44%和75%;自然型稳定塘中叶绿素a浓度较高,有助于氨氮和TP的去除.人工型稳定塘则对有机污染物具有更优的去除效果,对COD的质量去除率为32%;增加曝气装置、设置导流墙、加入载体等人工强化措施有利于对有机污染物的去除.     

A novel tracer technique for the assessment of fine sediment dynamics in urban water management systems

Urban storm water run off can reduce the quality of receiving waters due to high sediment load and associated sediment-bound contaminants. Consequently, urban water management systems, such as detention ponds, that both modify water quantity through storage and improve water quality through sediment retention are frequently-used best management practices. To manage such systems effectively and to improve their efficiency, there is a need to understand the dynamics (transport and settling) of sediment, and in particular the fine sediment fraction (<63 μm) and its associated contaminants within urban storm water management systems. This can be difficult to achieve, as modelling the transport behaviour of fine-grained and cohesive sediment is problematic and field-based measurements can be costly, time-consuming and unrepresentative.The aim of this study was to test the application of a novel cohesive sediment tracer and to determine fine sediment transport dynamics within a storm water detention pond. The cohesive sediment tracer used was a holmium labelled montmorillonite clay which flocculated and had similar size and settling velocity to the natural pond sediment it was intended to mimic. The tracer demonstrated that fine sediment was deposited across the entire pond, with the presence of reed beds and water depth being important factors for maximising sediment retention. The results of the sediment tracer experiment were in good agreement with those of a mathematical sediment transport model. Here, the deposited sediment tracer was sampled by collecting and analysing surface pond sediments for holmium. However, analysis and sampling of the three dimensional suspended tracer ‘cloud’ may provide more accurate information regarding internal pond sediment dynamics.     

Temperature influence on bacterial populations in three aquatic systems

Effects of temperature changes on bacterial populations in three aquatic systems were studied in the Thermal Effects Laboratory of the USAEC's Savannah River Laboratory. At monthly intervals for 12 months, total plate counts and diversity of heterotrophic, mesophilic bacteria were determined from a natural stream, two artificial streams, and two outdoor ponds. Water for artificial systems was drawn from the natural stream.Effects of changes in ambient temperature were analyzed in natural and artificial streams and in an unheated pond. A second pond was heated above natural stream temperature. Temperature elevation resulted in increased total plate counts in each system. Bacterial diversity increased in all systems during the initial 3–4°C increase in temperature. However, a reduction in diversity occurred when temperature was maintained 4–10°C above the initial ambient temperature. Changes were observed in both nutritional types and genera.     

Impact of oil and oil-dispersant mixtures on the fauna of freshwater ponds

In a series of 5 artificial ponds, one was treated with a nominal concentration of 100 ppm of crude oil, two others were treated with a nominal 100 ppm of oil and 20 ppm of dispersant. Mesozooplankton populations were reduced in the oil-treated pond relative to the control pond, and eliminated in the oil-dispersant ponds. This condition persisted until the following year when the mesozooplankton was similar in all ponds. The protozooplankton experienced species shifts with Halteria and Strobilidium being eliminated initially in all treated ponds, but Halteria was collected in samples the following spring. Other protozoans such as thecamoebae increased in the treated ponds, while others, like zooflagellates, did not appear to be affected by the chemicals. Zoobenthos was affected by treatment, with the number of different types being reduced. The zoobenthos had recovered in one of the treated ponds the following spring, and that in the other treated ponds were recovering. Surface insects were eliminated after treatment, but recolonized during the next spring. Nekton were initially reduced by treatment. The population changes are discussed with respect to the fate of oil.     

Measuring the trophic status of ponds: Relationships between summer rate of periphytic net primary productivity and water physico-chemistry

The monitoring of the water quality is a major environmental concern and specific method of assessment needs to be addressed for ponds. Among threats on freshwater, eutrophication remains an important and widespread problem. To assess if the trophic state of ponds can be significantly predicted by physico-chemical surrogates, parallel measurements of water physico-chemistry and of summer rates of periphytic net primary productivity (NPP) were performed on a set of nine lowland Swiss ponds representing the whole spectrum of trophic states.The developed methods to measure periphytic NPP on artificial substrates give similar values between the pseudo-replicates and are functional for ponds. The winter concentration of total nitrogen (TN) in the water is a significant predictor of the average summer rates of NPP while in submerged macrophyte beds total phosphorus (TP) is a better predictor. Rates of NPP measured in open water were most often higher and water transparency lower than in macrophyte beds, highlighting the positive influence of macrophytes on water quality and a possible co-occurrence in a pond of contrasting conditions when submerged species are present. This emphasizes the importance of maintaining or restoring submerged macrophyte stands in ponds to improve the water quality.     

Environmental factors and management practices controlling oxygen dynamics in agricultural irrigation ponds in a semiarid Mediterranean region: implications for pond agricultural functions

A water quality study was carried out on 40 irrigation ponds located within the main greenhouse areas on the Almería coast, placing special emphasis on the factors controlling the oxygen dynamics, a relevant aspect with agricultural and environmental implications. Considering chemical, physical and biological water characteristics, agricultural irrigation ponds were satisfactorily classified by cluster analysis in four groups. These were congruently arranged by principal components analysis along four main environmental gradients: trophic status, photosynthetic activity, water mineralisation and presence of submerged aquatic vegetation (SAV). Dissolved oxygen (DO) values differed highly among and within each of the four pond groups. DO dynamics was mainly depended on photosynthetic activity, and the environmental factors and management practices controlling it: seasonal and daily climatic changes, pond management (open vs. covered ponds and presence/absence of aquatic vegetation) and trophic status. Overall, different diurnal DO patterns were found between open and covered ponds. The former usually presented DO values above saturation and increasingly higher from early morning to mid-afternoon due to the photosynthetic activity of algae and macrophytic vegetation. In contrast, covered ponds showed relatively stable DO values during the diurnal period regardless of climatic conditions, with absolute values around or below saturation level. Globally, our results suggest that open ponds, with macrophytes concentrated in the deeper layer, can be an effective and sustainable management method of water oxygen enrichment.     

The impact of oil and oil-dispersant mixtures on fungi in freshwater ponds

The impact of oil and oil-dispersant mixtures on the mycoflora of a freshwater ecosystem was assessed using man made ponds. Data indicated that the ponds were well stabilized before pond treatment. Sufficient Norman Wells crude oil to give 100 ppm was added to each treated pond. The dispersant, Corexit 9527, was initially one-fifth of the oil concentration in the oil-dispersant-treated ponds.After pond treatment, an immediate increase occurred in the number of geoaquatic fungi in the oil-treated pond whereas an increase, followed by a sharp decrease, which was in turn followed by a recovery occurred in the oil-dispersant-treated ponds. The fungal enhancement effects, which were slight, were largely short term in duration (7–83 days).No clear cut medium or long term geoaquatic fungal enhancement effects were observed. The pond treatments had no detectable effect on the vertical distribution of fungi in the ponds. No significant treatment effects were observed on the water mould levels in the treated ponds. No obvious treatment effect was observed on the percentage of viable fungi capable of growth on non-degraded or biodegraded oil as a sole carbon source. Fifteen of 39 selected pond water fungi were able to grow on non-degraded Norman Wells oil. Corexit 9527 incorporated into agar plates inhibited the radial growth of the oil utilizing fungal isolates; EC₅₀ values were determined.     

Grundwasserfauna als Indikator für komplexe hydrogeologische Verhältnisse am westlichen Kaiserstuhl

Shallow groundwater is exposed to influence from surface waters to various degrees. These can be streams as well as natural and artificial lakes, such as quarry ponds. The degree of influence can be evaluated by hydrological or hydrochemical methods. It remains unclear to date, whether around the periphery of quarry ponds – where the aquifer is exposed unprotected to the atmosphere – an impact to groundwater can be demonstrated by the composition and abundance of metazoan communities below ground. Fourteen groundwater wells around the periphery of the Burkheimer quarry pond in the Upper Rhine Valley were sampled three to four times in 2009. Samples were analyzed hydrochemically and also for their fauna. The complex hydrogeological patterns in the investigated area were best reflected by four fauna groups. However, hydrological exchange processes overlay possible effects downstream of the quarry ponds. The marked fauna groups are “stressed sites”, characterized by a depleted groundwater fauna, “alluvial sites” with a species-rich fauna, showing the influence of surface water, “upwelling groundwater” that are characterized by a species-rich and abundant groundwater fauna, and “Rhine”, a well situated directly beside the Rhine River, with a stable and low variance of groundwater fauna that also showed low species numbers. Results show that hydrological exchange processes can be indicated by the composition of groundwater metazoan communities. Nonetheless, this survey did not reveal any direct effects on the groundwater fauna by the quarry pond.     

A compartmental model to describe hydraulics in a full-scale waste stabilization pond

The advancement of experimental and computational resources has facilitated the use of computational fluid dynamics (CFD) models as a predictive tool for mixing behaviour in full-scale waste stabilization pond systems. However, in view of combining hydraulic behaviour with a biokinetic process model, the computational load is still too high for practical use. This contribution presents a method that uses a validated CFD model with tracer experiments as a platform for the development of a simpler compartmental model (CM) to describe the hydraulics in a full-scale maturation pond (7 ha) of a waste stabilization ponds complex in Cuenca (Ecuador). 3D CFD models were validated with experimental data from pulse tracer experiments, showing a sufficient agreement. Based on the CFD model results, a number of compartments were selected considering the turbulence characteristics of the flow, the residence time distribution (RTD) curves and the dominant velocity component at different pond locations. The arrangement of compartments based on the introduction of recirculation flow rate between adjacent compartments, which in turn is dependent on the turbulence diffusion coefficient, is illustrated. Simulated RTD’s from a systemic tanks-in-series (TIS) model and the developed CM were compared. The TIS was unable to capture the measured RTD, whereas the CM predicted convincingly the peaks and lags of the tracer experiment using only a minimal fraction of the computational demand of the CFD model. Finally, a biokinetic model was coupled to both approaches demonstrating the impact an insufficient hydraulic model can have on the outcome of a modelling exercise. TIS and CM showed drastic differences in the output loads implying that the CM approach is to be used when modelling the biological performance of the full-scale system.     

Impact of oil and oil-dispersant mixtures on flora and water chemistry parameters in freshwater ponds

Oil and oil-dispersant mixtures at nominal concentrations of 100 and 20 ppm, respectively, were added to a series of ponds constructed for the study. In the pond treated with oil, there were no discernible short or long term effects on the phytoplankton. Both oil-dispersant treated ponds exhibited fluctuations in the dominant class of algae while the concentration of oil was greater than in the water column. Once the oil concentrations were below this value, there was no apparent effect. Periphytic material on the sides and bottoms of the oiled and control ponds were similar in mass and composed of a large number of species. Periphyton biomass was at least three times greater in both oil-dispersant-treated ponds with one genus dominating the growth. These conditions persisted in one of the oil-dispersant-treated ponds one year after treatment but those in the other pond had decreased to levels in the control pond at this time. Dissolved oxygen (DO) values decreased to about 4.6 ppm in both oil-dispersant-treated ponds shortly after treatment, but remained at approximately the saturation level in the other ponds for 6 weeks after treatment. Then these lower values gradually increased until they were slightly greater than in the controls. During the late winter months, both oil-dispersant ponds had anoxic zones above the sediment, the extent depending on the contours of the bottom. The DO values in the other ponds were at the saturation level. In the early spring, the nitrate ion-concentrations in control and oil-treated ponds were twice those measured for the oil-dispersant ponds. No discernible differences dependent on treatment were observed for nutrients or other ions monitored on a regular basis.     

Bioaccumulation of heavy metals in two wet retention ponds

Metal accumulation in stormwater ponds may contaminate the inhabiting fauna, thus jeopardizing their ecosystem servicing function. We evaluated bioaccumulation of metals in natural fauna and caged mussel indicator organisms in two wet retention ponds. Mussel cages were distributed throughout the ponds to detect bioaccumulation gradients and obtain a time-integrated measure of metal bioavailability. We further investigated if sediment metal concentrations correlate with those in the fauna and mussels. Metal concentrations in the fauna tended to be higher in the ponds than in a reference lake, but statistical significance was only shown for Cu. Positive correlations were found for some metals in fauna and sediment. Sediment metal concentrations in one pond decreased from inlet to outlet while no gradients were observed in the mussels in either pond. These findings indicate that metal accumulation in the examined ponds currently does not pose a threat to their habitat function.     

Characterization of roadway stormwater system residuals for reuse and disposal options

The chemical characterization of sediments accumulated in catch basins and stormwater ponds provides important information for assessing risks associated with management of these residuals upon removal of accumulated deposits in stormwater systems. In this study, over a period of 15 months, more than 150 residual samples were collected from 77 catch basin units and 22 stormwater ponds from 16 municipalities throughout the state of Florida. Concentrations (mg/kg) of metals and metalloids (arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, selenium, silver, and zinc) and trace organics (volatile organics, semi-volatile organics, herbicides, and pesticides) in the sediments were measured. In addition, the synthetic precipitation leaching procedure (SPLP) was utilized to evaluate pollutant leachability risk for a subset of the samples collected. Measured pollutant concentrations were compared to corresponding risk-based guidelines in Florida (i.e., Florida soil cleanup target levels) to assess potential human health risks of beneficial use of these residuals through land application. Leached concentrations were compared to risk-based water quality guidelines (i.e., Florida groundwater cleanup target levels) to examine the potential for groundwater contamination. Although several metals (arsenic, barium, chromium, copper, nickel, lead, and zinc) were routinely detected in the catch basin and stormwater pond sediments, their concentrations were generally lower than the Florida's risk-based cleanup target levels for soils. A small number of organochlorine compounds (e.g., 4,4′-DDE, 4,4′-DDT) were detected, but only in a limited number of the samples (less than 10%); leaching of trace organic pollutants above the Florida risk-based groundwater thresholds was rare. The results suggest that when land-applied or beneficially used, these residuals are not expected to pose a significant threat to human health or the environment and the results of this research will provide stormwater managers and environmental management authorities with a useful resource to examine proper disposal and beneficial use of catch basin and stormwater pond sediments.     

The fate of oil and oil—dispersant mixtures in freshwater ponds

The fate, distribution and composition of oil and oil—dispersant mixtures were studied in a series of five, lined, inground ponds containing sandy gravel sediment and mesotrophic water. Norman Wells crude oil and Corexit 9527 were added at nominal concentrations of 100 and 20 ppm, respectively, to two of the ponds, and the crude oil alone was added at 100 ppm to a third pond. The water surface, water column, the sediment, pond liner and attached biota were systematically sampled for a year. While only about 2% of the oil remained in the water column of the pond with no dispersant addition, in the pond with the dispersant, about 10% of the oil persisted in the water for several weeks. Most of the oil initially dispersed in the water returned to the water surface, then eventually sank to the sediment. Thinner surface films showed a higher dispersant content than the thicker slicks, and the thinner films had higher infrared carbonyl absorption. Final distribution calculations revealed that about 45% of the oil had degraded in the oil—dispersant-treated ponds during the one year study, while only 23% could not be accounted for in the oil pond. Changes in the oil composition during the experiment were similar in all ponds, with no evidence to suggest that the dispersant affected oil composition in any special manner.     

Upgrading a facultative pond by implanting water hyacinth

Water hyacinth was implanted in one of two existing facultative ponds and both units were operated in parallel under comparable conditions. The ponds were fed with mainly domestic wastewater after pretreatment in anaerobic ponds and operated at a BOD₅-loading of about 48 kg (ha d)⁻¹ and a detention time of 12 days. This paper covers a period of 4 months, from the implantation of the water hyacinths until no further systematic change in the treatment efficiency of the water hyacinth pond was observed. The median effluent concentrations of the facultative pond for SS, COD, TKN and TP were 55, 95, 6.4 and 1.4 mg l⁻¹, respectively. The values for the water hyacinth pond were 12, 26, 2.5 and 0.4 mg l⁻¹, respectively. The average DO effluent concentration of the water hyacinth pond was 1.2 mg l⁻¹, but this still increased slightly as compared to the influent. The study demonstrates that the implantation of water hyacinth is an appropriate option for upgrading facultative ponds. In many cases where more stringent effluent standards are imposed the method may be a suitable alternative to technical treatment processes.     

Sludge accumulation, characteristics, and pathogen inactivation in four primary waste stabilization ponds in central Mexico

To support the development of safe and feasible sludge management strategies, the accumulation rates of sludge and its characteristics were studied in four primary wastewater stabilization ponds (WSPs) in central Mexico (three facultative and one anaerobic). The accumulation rates and distribution of sludge were determined by measuring the thickness of the sludge layer at 8-40 locations throughout each pond. The average, per capita sludge accumulation rates ranged from 0.021 to 0.036m(3)/person/yr. In the anaerobic pond the sludge distribution was uniform throughout the pond, whereas in the three facultative ponds most of the sludge accumulated directly in front of the inlet. To measure the horizontal and vertical variation in the sludge characteristics, sludge cores were collected from 3 to 7 locations in three of the ponds. Each core was divided into 4 sub-samples in which various physical, chemical, and microbiological parameters were measured. In addition, the inactivation of several pathogen indicator organisms was studied in a batch of sludge for 7 months. Based on the microbiological results, it is concluded that reasonable estimates of the inactivation of fecal coliform bacteria, fecal enterococci, F+ coliphage, somatic coliphage, and Ascaris eggs in WSP sludge in central Mexico can be made using first-order rate constants of 0.1, 0.1, 0.01, 0.001, and 0.001d(-1), respectively. From the observed changes in the concentrations of total solids and the volatile to fixed solids ratio, empirical equations were developed to describe anaerobic degradation and compression, which are the two most important processes affecting the volume of sludge after its deposition.     

Computational fluid dynamics modelling of different detention pond configurations in the interest of sustainable flow regimes and gravity sedimentation potential

This study presents the results of the flow regime evaluation, by means of computational fluid dynamics (CFD), of a vegetated detention pond located at Waterlooville, Hampshire, UK. Alternative pond layouts were assessed for the same flow conditions on the basis of recommendations made in the literature. The results were validated by comparing the maximum computational velocities for the same case using different numbers of mesh elements. It was found that the development of a CFD model of detention ponds is intricate but feasible. The main findings were: (i) The present design performed well in terms of flood risk management, but the flow patterns could result in questionable treatment efficiency; (ii) vegetation seems to promote horizontal recirculation and turbulence; (iii) triangular and elliptical pond designs showed very poor performance; (iv) the most appropriate design for the given location and hydrological regime is an elliptical pond with a central emergent/submerged island.     

Nitrogenous compounds in facultative oxidation pond sediments

The protein content of sludge samples from facultative oxidation ponds was measured and was found to have even distribution in the pond floor. Proteolytic activity which degrades protein to intermediate compounds, was found to be slightly higher near the pond inlet region. It was also shown that proteolytic activity increased with increasing depth of overlying pond liquor.Ammonia content of, and ammonification by pond sludge appeared to be independent of locality. Urea and urease activity were restricted to the regions close to the pond inlet region.     

Modelling of coliform removal in 186 facultative and maturation ponds around the world

The paper presents a very extensive evaluation of the coliform decay in facultative and maturation ponds, based on data from 186 different ponds in the world. The ponds encompass a very wide diversity in terms of physical and operating conditions, covering most situations encountered in practice. The median values for the coliform removal efficiencies were 1.8 log units (98% removal) for primary facultative ponds, 1.0 log units for secondary facultative ponds (90% removal) and 1.2 log units (94% removal) for each maturation pond in the series. Two equations to be used for design purposes were derived for estimating the die-off coefficient K(b) (dispersed flow, 20 degrees C) in facultative and maturation ponds. The first equation led to a slightly better fitting with the observed logarithm of the effluent coliform concentrations (R2 = 0.874), and related K(b) with the pond detention time t and depth H (K(b) = 0.682 H(-1.286) t(-0.103)). The other equation also led to a satisfactory fitting (R2 = 0.845), but was slightly simpler, depending only on the pond depth (K(b) = 0.549 H(-1.456)).