Basin Effluent Research Articles

Characteristics of particle formation in O3-UBAC filter and effects of operational parameter on particles

The ozone oxidation and up-flow biological activated carbon (O3-UBAC) process has been recognized for its ability to extend the operating cycle of biological activated carbon (BAC) filters by expanding the carbon layer and maintaining a dynamic balance of the carbon biofilm. However, the primary focus of O3-UBAC is the removal of organic pollutants, often overlooking the treatment of particles. To address this gap, a pilot-scale study was conducted using sedimentation basin effluent samples from a drinking water treatment plant (DWTP), which were added into BAC columns. The study aimed to investigate the seasonal variation of effluent particles during the UBAC operating cycle, including particle counts, size distribution, and mass composition. Based on particle characteristics and the combined effects of adsorption and biodegradation, the UBAC operation cycle was divided into three periods. Results revealed that hydraulic impacts and biofilm desorption on carbon could increase the proportion of particles >5 μm in effluent. Pre-ozonation demonstrated significant effects on particle counts and Heterotrophic Plate Count (HPC) levels (p < 0.05), with the addition of 1 mg/L O3 resulting in a reduction in particle counts in the effluent. Moreover, particle removal could be achieved by adjusting the upward flow velocity, necessitating comprehensive consideration of pollutants. Furthermore, microbial community analysis under optimal operating conditions unveiled significant changes in the microbial diversity of UBAC-treated water particles. Although the influent and effluent exhibited similarities at different phylum levels, the dominant bacteria differed significantly at various levels.

Investigation of the Phycoremediation Potential of Freshwater Green Algae Golenkinia radiata for Municipal Wastewater

Recent developments in the removal of pollutants from wastewater show that phycoremediation to wastewater treatment and reuse wastewater may provide sustainable biosolutions. This work investigated the performance of the green microalgae Golenkinia radiata Chodat 1984 (Chlorophyceae) in terms of N, P, and COD removal at different treatment stages of municipal wastewater, reusability of remediated wastewater and wastewater-based biomass production. Water samples were taken from different wastewater units (presettling basin effluent, active sludge basin effluent, and discharge channel) of a municipal wastewater treatment plant (İzmir, Turkey). In the 7-day experiments, Chl-a, Chl-b, DO, pH, and T (°C) were also measured alongside the pollutant analyses. The results in Chl-a (1803 ± 75.9 µg L−1) and biomass yield (7.66 ± 0.05 g L−1) in the primary effluent (P) were quite impressive. Additionally, the results showed that the correlation between the increase in Chl-a and the residual concentrations of pollutants was remarkable. NH4-N, NO3-N, NO2-N, PO4-P, and COD treatment efficiencies were in the ranges of (74.6–83.0%), (15.35–70.4%), (0.00–47.22%), (80.67–86.27%), and (77.22–87.53%), respectively. The final concentrations of pollutants (E) were found to comply with EU legislation. The results also reveal that green microalgae G. radiata may be a strong candidate for microalgae-based wastewater treatment.

Pilot plant demonstration of stable and efficient high rate biological nutrient removal with low dissolved oxygen conditions

Aeration in biological nutrient removal (BNR) processes accounts for nearly half of the total electricity costs at many wastewater treatment plants. Even though conventional BNR processes are usually operated to have aerated zones with high dissolved oxygen (DO) concentrations, recent research has shown that nitrification can be maintained using very low-DO concentrations (e.g., below 0.2 mg O2/L), and therefore, it may be possible to reduce energy use and costs in BNR facilities by decreasing aeration. However, the effect of reduced aeration on enhanced biological phosphorus removal (EBPR) is not understood. In this study, we investigated, at the pilot-scale level, the effect of using minimal aeration on the performance of an EBPR process. Over a 16-month operational period, we performed stepwise decreases in aeration, reaching an average DO concentration of 0.33 mg O2/L with stable operation and nearly 90% phosphorus removal. Under these low-DO conditions, nitrification efficiency was maintained, and nearly 70% of the nitrogen was denitrified, without the need for internal recycling of high nitrate aeration basin effluent to the anoxic zone. At the lowest DO conditions used, we estimate a 25% reduction in energy use for aeration compared to conventional BNR operation. Our improved understanding of the efficiency of low-DO BNR contributes to the global goal of reducing energy consumption during wastewater treatment operations.

Examination of possible energy conservation in a biological water treatment process using a multiple regression model

This study examined various controls and operating parameters of a sewage treatment plant by performing multiple regression analyses on the operating parameters and the effluent quality of the sewage treatment plant. For the examination, operating data from April to November, 2012, was collected from a sewage treatment plant using the media anaerobic-anoxic-oxic method. The chemical oxygen demand (CODMn) and total nitrogen (T-N) forecasting models for the secondary sedimentation basin effluent were built through multiple regression analysis and showed Mean Absolute Percentage Error (MAPE) 6.6–9.3 and 16.0–23.7, respectively. All models showed similar results to real observational data. When controlling the operating parameters of CODMn and T-N, by using the regression model and the standardization regression coefficients without violating legal water quality criteria, operating conditions can be set that save an average of 23% of power consumption. Using this result, an operating guide for low energy consumption can be provided to the operators of sewage treatment plants.

Methane and nitrous oxide analyzer comparison and emissions from dairy freestall barns with manure flushing and scraping

Continuous methane (CH4) and nitrous oxide (N2O) emission measurements were conducted at two crossflow-ventilated dairy freestall barns located in the state of Wisconsin, USA during a 19-month period from 2008 to 2010. The two cross-flow mechanically ventilated buildings (275 and 375 cow capacities) were evaluated in the National Air Emissions Monitoring Study. In September of 2008, the barns' manure collection systems were changed from flushing open gutter using manure basin effluent to a tractor scrape. A photoacoustic multi-gas analyzer (PAMGA) and a direct methane/non-methane hydrocarbon analyzer (GC-FID) provided side-by-side measurements of methane (CH4) for 13 months. The PAMGA also measured nitrous oxide (N2O), and a side-by-side comparison was performed with a gas-filter correlation analyzer (GFC) for six months. Barn ventilation rates were measured by recording run times of the 127-cm diameter exhaust fans. All 125 belt-driven exhaust fans were identical, and in situ airflow measurements using the Fan Assessment Numeration System (FANS) were conducted once at the beginning and twice during the test. Daily CH4 and N2O emission rates were calculated over approximately 19 and 6 month periods respectively, on per barn, head, animal unit, floor area space and barn capacity bases. The differences between the analyzers' concentration measurements were compared in conjunction with water vapor and other gases. The analyzer type had a significant impact on the average CH4 emission rate (p < 0.001) and the average N2O emission rate (p < 0.05). Based on the CH4 measurements with the GC-FID, average daily mean CH4 emissions were approximately 290 g AU−1 d−1 (390 g cow−1 d−1) with very limited seasonal effects. Little variation was observed in CH4 emission rates before and after the change in manure collection method, suggesting that most of the CH4 emissions were enteric losses directly from the cows. The average daily mean N2O emission rates based on the GFC were very low, with an approximate rate of only 690 mg AU−1 d−1 (970 mg cow−1 d−1). The change in manure collection had no apparent effect on N2O emission.

Reuse of ferric sludge as an iron source for the Fenton-based process in wastewater treatment

Abstract A mature municipal landfill leachate (S1), a wood soaking basin effluent from a plywood manufacturing plant (S2), and a leachate collected from a semicoke landfill area of an oil-shale thermal treatment plant (S3) were subjected to the Fenton/Fenton-based treatment (H 2 O 2 /Fe 2+ , H 2 O 2 /Fe 3+ and H 2 O 2 /sludge systems). The results of ferric coagulation trials indicated a high efficacy in S2; thus, only pre-coagulated samples (cS2) were further treated by the H 2 O 2 /iron systems. Irrespective of reaction duration, S1 was more recalcitrant to oxidation than cS2 and S3. The optimal COD/H 2 O 2 weight ratio for cS2 and S3 was 1:1 with respective 21(35) and 36(45)% residual COD(DOC). In the case of S1, the COD/H 2 O 2 w/w of 1:3.45 proved the most efficient with 30 and 35% residual COD and DOC, respectively. The results also indicated an increase in BOD 7 /COD ratio and a reduction in the acute toxicity to Daphnia magna of the studied wastewater samples after the Fenton/Fenton-based treatment. The application of the Fenton-based process catalysed with iron-containing sludge exhibited efficacies similar to classical Fenton treatment over four reuse cycles. The reuse of ferric sludge without any regeneration as an iron source in the Fenton-based process was displayed as a feasible solution to minimise the production of hazardous ferric waste and reduce the overall cost of the treatment process.

Impact of system management on vegetative treatment system effluent concentrations

Beef feedlots of all sizes are looking for more cost-effective solutions for managing feedlot runoff. Vegetative treatment systems are one potential option, but require performance evaluation for use on concentrated animal feeding operations. The performance of six vegetative treatment systems on open beef feedlots throughout Iowa was monitored from 2006 through 2009. These feedlots had interim, National Pollution Discharge Elimination System permits that allowed the use of vegetative treatment systems to control and treat runoff from the open feedlots. This manuscript focuses on making within site comparisons, i.e., from year-to-year and component-to-component within a site, to evaluate how management changes and system modifications altered performance. The effectiveness, in terms of effluent concentration reductions, of each system was evaluated; nutrient concentration reductions typically ranged from 60 to 99% during treatment in the vegetative components of the vegetative treatment systems. Monitoring results showed a consistent improvement in system performance during the four years of study. Much of this improvement can be attributed to improved management techniques and system modifications that addressed key performance issues. Specifically, active control of the solid settling basin outlet improved solids retention and allowed the producers to match effluent application rates to the infiltration rate of the vegetative treatment area, reducing the occurrence of effluent release. Additional improvements resulted from system maturation, increased operator experience, and the addition of earthen flow spreaders within the vegetative treatment area to slow flow and provide increased effluent storage within the treatment area, and switching to active management of settling basin effluent release.

Comparison of the Iowa State University Effluent Limitation Guidelines Model with the Soil-Plant-Air-Water Model for Evaluating Containment Basin Performance

This article compares results from the Iowa State University Effluent Limitations Guidelines (ISU-ELG) model to results obtained using the Soil-Plant-Air-Water (SPAW) model to simulate feedlot runoff containment basin overflow volume. The objective was to verify that the ISU-ELG model was providing a reasonable prediction of basin overflow. The ISU-ELG model uses a set of guidelines to determine if land application is acceptable, whereas the SPAW model uses a soil moisture criterion. The criterion for determining if a particular day was suitable for land application of basin effluent was investigated to determine the effect on basin overflow volumes. The results show that the ISU-ELG model overpredicted the percentage of feedlot runoff controlled in comparison to the SPAW model at all five locations investigated. For wetter areas in Iowa, the number of drying days had a large effect on basin overflow volumes, whereas for the drier northwest region of Iowa, this effect was limited. Possible methods of improving the ISU-ELG model predictions include adding a soil moisture accounting function to model moisture levels in the land application area or calibrating the number of drying days required before land application can commence. Alternatively, the SPAW model can be used, but this requires additional user inputs and increases complexity in modeling the runoff control system.

EFFECTS OF CONSTRUCTION SITE SEDIMENTATION BASINS ON RECEIVING STREAM ECOSYSTEMS

The effects of sedimentation basin discharges on receiving stream ecosystems were investigated for threeconstruction sites in Lancaster County, Pennsylvania. Samples were collected in the receiving stream at two locationsupstream and downstream from the basin outlet pipe and directly from the outlet pipe while the basin was dischargingfollowing rainfall events. Suspended sediment concentration, particle size distribution, benthic macroinvertebrates, andtemperature were evaluated at each location. Stream temperature increased slightly (+0.3C) on the discharge side of thestreams immediately below the sedimentation basins, but the elevated temperatures did not extend farther downstream.Stream sediment concentrations increased significantly (p < 0.05), and the high concentrations persisted to the downstreamsampling site located 100 m below the basin discharge. During storm events, the basin effluent contributed a larger proportionof finer suspended sediments, as measured by particle size distribution, than the stream, and the smaller particle sizespersisted downstream. There was no significant change in number of macroinvertebrate individuals as a result of thesedimentation basin discharge, but there was a significant decrease in the number of taxa observed in the receiving streamdirectly below the basin outlet. However, this observed reduction in species richness was not significant 100 metersdownstream from the basin discharge pipe.

Bubble Collector Captures Third Place

A bubble collector was designed to trap and collect air that is carried down with the lime slurry discharge, and release it to the water surface without adding to the turbidity of the basin effluent. Before the bubble collectors were installed at the lime‐softening plant in Sioux Falls, South Dakota, the average effluent turbidity of the worst basin was 9.0 to 10.0 ntu. With the bubble collectors, the average effluent turbidity dropped to less than 5.0 ntu, and is usually under 4.0 ntu.

Particle Behavior in Deep‐Bed Filtration: Part 1—Ripening and Breakthrough

Laboratory‐scale filtration experiments were conducted using sedimentation basin effluent from a local lime‐softening water treatment plant. An electronic particle counter was used to observe changes in the particle size distribution of the filtrate as a function of filter depth and time under a variety of filter operating conditions. The experiments were conducted for an extended period (up to 48 h) to observe the effects of both ripening and breakthrough over the duration of a typical water treatment plant filter cycle. The results indicate that ripening and breakthrough are not distinct stages but occur simultaneously for different‐size particles. The effects of media size and filtration velocity were investigated, and simple normalizations were developed.

Certification Corner

This month's “Certification Corner” presents questions on the effects of aeration on well water, the use of color‐producing chemicals in the residual chlorine test, sedimentation basin effluent weirs, coliform testing, gate valve placement, corrosive water, and movement of underground bacterial pollution.

The uptake of chemical elements from coal ash and settling basin effluent by primary producers II. Relation between concentrations in ash deposits and tissues of grasses growing on the ash

A number of reports of biomagnification of trace metals by plants indicate that elements are selectively concentrated within certain tissues when plants grow on coal ash. This study determined the uptake by, and tissue bioaccumulation of, 15 chemical elements within broom sedge and nut grass growing in the drainage system of a coal ash basin. Biomagnification of these elements by the grasses was compared to concentrations of these elements found in duckweed within the same system. Aluminium, arsenic, barium, cadmium, cobalt, chromium, copper, iron, mercury, manganese, molybdenum, selenium, strontium, titanium, and zinc were measured by neutron activation analysis in roots, stems, leaves and fruit of the grasses which grew in sediments within the effluent. Mercury and zinc were biomagnified in both grasses and duckweed to a level exceeding the concentration in sediment. All elements were biomagnified above the water concentration in all parts of the plants. Bioaccumulation of elements in the leaves and fruit of these plants provides a concentrated source of potentially toxic chemical elements for passage to animals which may consume these plants. The mechanisms of movement of potentially toxic elements from coal ash or water into food webs need additional study as utilization of coal is increased.

The uptake of chemical elements from coal ash and settling basin effluent by primary producers I. Relative concentrations in predominant plants

Chemical elements are released to the surface waters in large concentrations from coal ash, when ash is sluiced from the plant to a settling basin, or disposed on land surfaces. The role of primary producers growing in the drainage system receiving ash basin effluent, in removal or cycling of chemical elements from coal ash, has been investigated. Aquatic plants in the drainage system were collected and analyzed by neutron activation to determine concentrations of 23 chemical elements present in the coal ash effluent. The predominant aquatic producers present were Lemna perpusilla (duckweed), Typha Latifolia (cattail), Pontederia sp., Taxodium distichum (bald cypress), and the algae Oscillatoria sp. and Hydrodictyon sp. Leaves were collected from cattail, cypress and Pontederia sp., and the entire plants were collected from duckweed, Oscillatoria sp. and Hydrodictyon for analysis. Analysis of concentrations showed that duckweed, cattail, Oscillatoria sp. and Hydrodictyon sp. were the most efficient biomagnifiers of the 23 chemical elements. All elements were concentrated by the majority of the plants present relative to the concentration of the elements in the water in which the plants grew. This biomagnification of chemicals appears to be an important mechanism for removal of these elements from the drainage system water.

Influence of process loading intensity on sludge clarification and thickening characteristics

The separation of microbial mass in an activated sludge system depends on the formation of large settleable sludge flocs. Microbial cells agglomerate into small clumps and subsequently into sludge flocs by a natural bioflocculation process. The resulting biological mass may exist as individual cells, small aggregates, or large flocs in the aeration basin effluent. In the secondary clarifier, only large flocs are separated by sedimentation while individual cells and small aggregates are washed out as effluent suspended solids. In the present study, the separation of sludge by sedimentation was shown to be closely related to the surface roughness of the resulting flocs. Normal sludges were observed to have relatively smooth surfaces while filamentous and zoogloeal bulking sludges were noted to have rough and diffused surfaces. The filamentous growths and the non-filamentous protuberances on the bulking sludge surface serve to increase the frictional drag between the moving solid and the liquid. This contributes to a lower settling velocity and associated dewatering rate of bulking sludges. Conversely, the quantity of non-settleable solids was shown to be related to the quantity of extracellular biopolymers excreted by the microorganisms. The quantity of biopolymers produced decreased for higher Process Loading Intensity or lower sludge age levels thereby resulting in poor aggregation of cells into clumps and subsequently into flocs. This contributes to low clarification efficiencies of the activated sludge process.

The effects of coal ash basin effluent and thermal loading on bacterial populations of flowing streams

Water quality parameters and elemental concentrations were studied for a period of one year in an ash basin drainage system. Measurements were made in streams heated by thermal discharge from an electric power plant and in a non-polluted reference stream. Water samples from four stations were cultured for total culturable heterotrophic bacteria in the water column, number of chromagenic colonies and total number of different colony types (diversity). Both thermal loading and large concentrations of chemical elements from the coal ash basin reduced diversity and percentage chromagens, although increasing total culturable bacteria. Temperature appeared to have a greater effect on community stability characteristics than did increased elemental concentration on the naturally-occurring bacterial populations in these systems.

Mode of elemental dissipation from ash basin effluent

The dissipation of chemical elements from ash basin effluent was determined by use of neutron activation analysis of sediment, water, plant, invertebrate, and vertebrate samples taken from successive sites through the drainage system. Samples were tested for concentrations of 40 elements for a 12 mo period. Three different modes of dissipation were found. The major mechanism for removal of chemical elements from effluent was sedimentation into the benthic sediment. All biota had greater concentrations of chemicals than did water, with invertebrates having slightly higher levels than did plants and vertebrates. Ten elements were more concentrated in at least one biotic group than in the sediment. Concentrations of six elements in the drainage system exceeded the EPA recommended limits for surface waters. The observed modes of dissipation in this aquatic system emphasize the necessity for stable biotic communities present to permit cycling of chemical elements.