bluuebunny/crossref_metadata_2025 huggingface dataset:
Ecological characteristics of a natural wetland receiving secondary effluent
Authors: Martin J.R. , Clarke R.A. , Knight R.L.
Published: May 2018

The Boot wetland treatment system is a 115-acre, hydrologically altered cypress-gum wetland in Polk County, Florida. The Poinciana Wastewater Treatment Plant No. 3 has discharged secondary effluent to the bermed Boot wetland since August 1984. Before that time this natural wetland had been affected adversely by forestry, drainage, and surrounding development which contributed to dying trees and a groundcover of invasive upland plants. In accordance with the Florida Department of Environmental Protection's Wetlands Application Rule (Chapter 62-611, F.A.C.), a routine biological and water quality monitoring program has been in effect since October 1990. Components of the biological monitoring program include surveys of canopy and subcanopy, herbaceous and shrub groundcover species, benthic macroinvertebrates, fish, and nuisance mosquitoes. Effluent addition to the Boot wetland has resulted in continuous wetland inundation with a typical water depth of 2.5 to 3.0 feet for the past 15 years. Dominance and density of trees has steadily increased, upland invader species were eliminated, and stable plant, fish, and invertebrate communities were established. The long term biological data from this treatment wetland is compared to data from other natural treatment wetlands and a control wetland.
Protection of surface water against contamination by wetland systems in Poland
Authors: Obarska-Pempkowiak H. , Ozimek T. , Chmiel W.
Published: May 2018

Facilities constructed in order to protect streamS against storm water in the Gdan«sk region are described. The first of them is located on the Rynarzewski Stream (water flow 25 l/s). The stream is the main tributary of the Jelitkowski Stream which in turn drains to the Baltic Sea in the area of popular beaches and hotels. Results of analyses indicate the improvement of water quality in the stream and along beaches in this region. Another facility is situated on the Swelina Stream (water flow 30 l/s). The stream is fed with storm water originating from residential districts. In order to improve water quality a pond was constructed supported by a subsurface flow filter (HF-CW type). After implementation of the system substantial improvement of water quality occurred. In order to protect drinking water intake for the city of Gdan«sk against surface and point sources of contaminants a hydrophite treatment system was constructed in Bielkowo. The system consists of two subunits: wet unit (pond), filled with water all the time and dry unit (extention of the pond), designed for storm water. In the wet unit dams constructed of medium size sand are placed. The system, especially the dams, is inhibited with reed. The drainage systems collect water percolating through the dams, and directs it downstream. The system was constructed in 1997. Since then it has proven a substantial improvement of water quality discharged of inflowing loads, on average.
Reciprocating constructed wetlands for treating industrial, municipal and agricultural wastewater
Authors: Behrends L. , Houke L. , Bailey E. , Jansen P. , Brown D.
Published: May 2018

Scientists at the Tennessee Valley Authority (TVA), and in collaboration with the U.S. Environmental Protection Agency (EPA), are continuing to develop and refine an innovative wastewater treatment system referred to as reciprocating subsurface-flow constructed wetlands. Reciprocation relates to patented improvements in the design and operation of paired subsurface-flow constructed wetlands, such that contiguous cells are filled and drained on a frequent and recurrent basis. This operating technique turns the entire wetland system into a fixed-film biological reactor, in which it is possible to control redox potential in alternating aerobic and anaerobic zones. Reciprocating systems enable manipulation of wastewater treatment functions by controlling such parameters as hydraulic retention time, frequency of reciprocation, reciprocation cycle time, depth of reciprocation, and size and composition of substrate. These improved wetland technologies have been used for treating municipal/domestic wastewater, high strength animal wastewater, and mixed wastewater streams containing acids, recalcitrant compounds, solvents, antifreeze compounds, heavy metals, explosives, and fertilizer nutrients. Results from selected treatability studies and field demonstrations will be summarized with respect to conceptual design and treatment efficacy.
The effect of refinery effluent on the aquatic macrophytes Scirpus californicus, Typha subulata and Zizaniopsis bonariensis
Authors: Campagna A.R. , da Motta Marques D.
Published: May 2018

Experimental wetlands were built to follow the implementation and permanence of three species of aquatic macrophytes (Scirpus californicus, Typha subulata and Zizaniopsis bonariensis) under different treatments (water, water + nutrients and water + nutrients + refinery effluent). Morphological variables (number of lateral shoots produced, height of the main lateral shoot and final density values) were used to check the influence of a petrochemical effluent. All the response variables showed significant differences (p=5%) in their development, mainly between the water treatment and water + nutrient + effluent, followed by water with water + nutrients. In the Water treatment, the lowest variable values were found for the three species, possibly due to the lack of nutrients in the medium. Opposite results were found in the other treatments, indicating that the petrochemical effluent was not a limiting factor for the implementation of the species in the systems.
Tolerance towards explosives, and explosives removal from groundwater in treatment wetland mesocosms
Authors: Best E.P.H. , Miller J.L. , Larson S.L.
Published: May 2018

A short-term study was performed to determine the feasibility of using constructed wetlands to remove explosives from groundwater, and to assess accumulation of parent explosives compounds and their known degradation compounds in wetland plants. Tolerance towards explosives in submersed and emergent plants was screened over a range of 0 to 40 mg L-1. Tolerance varied per compound, with TNT evoking the highest, 2NT the lowest, and 24DNT, 26DNT, and RDX an intermediate growth reducing effect. Submersed plants were more sensitive to TNT than emergent ones. A small-scale 4-month field study was carried out at the Volunteer Army Ammunition Plant, Chattanooga, TN. In this surface-flow, modular system, the influent contained high levels (>2.1 mg L-1) of TNT, 2,4DNT, 2,6DNT, 2NT, 3NT, and 4NT, and the HRT was 7 days. The performance criteria of US EPA treatment goals for local discharge of 2,4DNT concentration <0.32 mg L-1, and 26DNT concentration <0.55 mg L-1 were not met at the end of the experiment, although explosives levels were greatly reduced. Low levels of 2ADNT and 4ADNT were transiently observed in the plant biomass. Results of two other, older, constructed wetlands, however, indicated that in these systems treatment goals were met most of the time, residues of explosives parent compounds and known degradation compounds in plant tissues were low and/or transient, and in substrates were low.
Application of a constructed wetland for non-point source pollution control
Authors: Kao C.M. , Wang J.Y. , Lee H.Y. , Wen C.K.
Published: May 2018

In Taiwan, non-point source (NPS) pollution is one of the major causes of impairment of surface waters. The main objective of this study was to evaluate the efficacy of using constructed wetlands on NPS pollutant removal and water quality improvements. A field-scale constructed wetland system was built inside the campus of National Sun Yat-Sen University (located in southern Taiwan) to remove (1) NPS pollutants due to the stormwater runoff, and (2) part of the untreated wastewater from school drains. The constructed wetland was 40 m (L) × 30 m (W) × 1 m (D), which received approximately 85 m3 per day of untreated wastewater from school drainage pipes. The plants grown on the wetland included floating (Pistia stratiotes L.) and emergent (Phragmites communis L.) species. One major storm event and baseline water quality samples were analyzed during the monitoring period. Analytical results indicate that the constructed wetland removed a significant amount of NPS pollutants and wastewater constituents. More than 88% of nitrogen, 81% of chemical oxygen demand (COD), 85% of heavy metals, and 60% of the total suspended solids (TSS) caused by the storm runoff were removed by the wetland system before discharging. Results from this study may be applied to the design of constructed wetlands for NPS pollution control and water quality improvement.
Buffer zones promoting oligotrophication in golf course runoffs: fiddler crabs as estuarine health indicators
Authors: George R.Y. , Bodnar G. , Gerlach S.L. , Nelson R.M.
Published: May 2018

Nitrogen pollution above a threshold level induces a eutrophication process in coastal creek ecosystems and consequently impacts on the water quality. The remedy for this scenario is the introduction of methods to enhance oligotrophication by means of constructed wetlands and buffer zones. This paper discusses new data on nitrogen flux and population changes in the primary consumers in the Bradley Creek ecosystem, adjacent to the Duck Haven Golf Course in southeastern North Carolina. In 1998-99, over different seasons, density distribution of the field populations of the fiddler crab Uca minax, was monitored as an indicator of environmental health. A control site at Whiskey Creek, adjacent to the University Center for Marine Sciences, was monitored in the same period since this site is not influenced by any golf course nutrient flux. The results pointed out that threshold level for optimum population density in Spartina grandiflora salt marsh is 0.1 mg/L of nitrates. A dense crab population, adjacent to the golf course with a buffer zone, was indicative of restoration of the estuarine ecosystem. A model, involving the use of constructed wetlands for oligotrophication, is being prepared on the basis of studies conducted by the University of South Alabama for a stormwater wetland constructed adjacent to the university's golf course.
The influence of thermal stratification on the hydraulic behavior of waste stabilization ponds
Authors: Kellner E. , Pires E.C.
Published: May 2018

Thermal stratification, which is characterized by a high vertical thermal gradient, is usually observed in deep lakes. However, although waste stabilization ponds have small depths, their high turbidity provides favorable conditions for the occurrence of this phenomenon, mainly during summer. During that time of the year, the layers nearest to the surface concentrate a larger amount of thermal energy compared to the deeper layers, which results in a temperature difference between the surface and the bottom of the pond. As a consequence a density profile appears, with the less dense layers located at the surface of the pond and the densest ones close to the bottom. This stratification in the water column induces alterations in the flow pattern and a decrease of the useful volume of the pond. This paper presents a mathematical model developed to forecast the conditions of thermal stratification in waste stabilization ponds and the volume actually used for wastewater treatment. With these values it is possible to correct the average residence time of the liquid in the pond. The theoretical results were compared with experimental observations, and maximum differences of 15% between the calculated and observed temperature profiles were found.
Performance of a baffled facultative pond treating piggery wastes
Authors: Zanotelli C.T. , Medri W. , Belli Filho P. , Perdomo C.C. , Mulinari M.R. , Costa R.H.R.
Published: May 2018

This paper shows the performance of a baffled facultative pond for the treatment of piggery wastes. The full-scale system is composed of an equalizer, one decanter (DP), two anaerobic ponds (LA1 and LA2), one facultative pond (LF), with five baffles, and one maturation pond with water hyacinths (LAG). The studies were conducted over a 12 month period in the west region of Santa Catarina, Brazil. The system was supplied daily with a volume of 3 m3/day of farm wastes. A good performance of the treatment system was obtained with average removal efficiencies of 98% for chemical oxygen demand, 93% for total solids, 98% for total phosphorus, 92% for total nitrogen, 7 log units of faecal coliforms and 5 log units of total coliforms. The facultative pond performed well, removing 43% of the chemical oxygen demand, 47% of total nitrogen and 54% of total phosphorus. It was found that the first baffle in the facultative pond was mainly responsible for the efficiency of this pond, and compared with another study the introduction of the baffles improved the removal efficiency by 20% for total phosphorus.
Treatment of piggery wastes in waste stabilization ponds
Authors: Estrada V.E.E. , Hernández D.E.A.
Published: May 2018

The piggery industry produces high effluent loads. This is due to the high concentration of animals kept in a confined space, foods with high protein content that are not well assimilated by the animals, and poor on-farm water management. In this study, we present the characteristics, design, site selection, soil study, and the construction of a pilot pond system for a family farm located in a warm climate area. The design includes a solids sedimentation phase, an anaerobic pond, a facultative pond and three maturation ponds. Once the system had reached steady state, the organic and bacterial kinetic constants were determined for each pond. The control parameters were determined and the dissolved oxygen and removal efficiency profiles were obtained. The results indicate that the effluent from the second maturation pond complies with the Official Mexican Standard for reuse in agriculture (≤1000 FC/100 ml).
Process performance assessment of algae-based and duckweed-based wastewater treatment systems
Authors: Zimmo O.R. , Al-Sa'ed R.M. , van der Steen N.P. , Gijzen H. J.
Published: May 2018

A pilot plant experiment was carried out to assess differences in environmental conditions and treatment performance in two systems for wastewater treatment: algae-based ponds (ABP) and duckweed-based (Lemna gibba) ponds (DBP). Each system consisted of a sequence of 4 equal ponds in series and was fed with a constant flow rate of partially treated wastewater from Birzeit University. Physico-chemical parameters and the removal of organic matter, nutrients and faecal coliforms were monitored within each treatment system over a period of 12 months. The results show clear differences in the environmental conditions. In ABP significantly (P>0.05) higher pH and DO values were observed than in DBP. DBP were more efficient in removal of organic matter (BOD and TSS) than ABP. The faecal coliform reduction was higher in ABP. However, the quality of the effluent from the third and fourth duckweed pond (total retention time of 21 and 28 days) did not exceed the WHO-criteria for unrestricted irrigation during both the summer and winter period, respectively. During the summer period, the average total nitrogen was reduced more in ABP (80%) than in DBP (55%). Lower values were measured during the winter period. Seasonal nitrogen reductions of the two systems were significantly different (P>0.05). In DBP, 33% and 15% of the total nitrogen was recovered into plant biomass and removed from the system via duckweed harvesting during the summer and winter period, respectively. This study showed that there were differences in the environmental conditions and treatment efficiencies between the two systems.
WMO questionnaire on recording precipitation gauges: state-of-the-art
Authors: Sevruk B.
Published: May 2018

To receive information on recording precipitation gauges used operationally by national meteorological services the World Meteorological Organization started a worldwide inquiry. This included the type of recording precipitation gauge (RPG), their manufacturer, measuring system applied, number of RPGs used, methods of recording and data transmission, orifice area size and installation heights, heating and windshield application as well as the question on the need to organising global intercomparisons of RPG measurements. The results of the 118 responses received (out of 180 countries) are presented and discussed. They show that there is a great variety in instruments and methods of observation of precipitation intensity used not only worldwide but also in the same country. This variety exceeds by far the variety in manual standard precipitation gauges.
Detection of the most optimal measuring points for water quality variables: application to the river water quality model of the River Dender in ESWAT
Authors: Vandenberghe V. , van Griensven A. , Bauwens W.
Published: May 2018

This paper presents a methodology for the definition of an optimal set of sampling data for the calibration of a river water quality model. Starting with an extensive set of measurements, it is the aim to reduce those data to obtain just as much data as necessary for a calibration with an acceptable uncertainty in the parameters. The method requires a model for the river under examination and the availability of samples for a first calibration of the model. With the model, synthetic time series are generated, which can be used as virtual observations. In the next step, the method of D-optimal design is applied. The amount, frequency, period, place and kind of variables measured of the water samples that gives the most reliable estimates of the parameters of the model are considered to be the best observations that can be made for that river. Also, the percentage of improvement of the reliability can be defined, as a function of the observations. The method is applied to the river Dender.
The sewer as a bioreactor – a dry weather approach
Authors: Hvitved-Jacobsen T. , Vollertsen J. , Matos J.S.
Published: May 2018

The sewer is a reactor for chemical and microbial transformations of wastewater. These in-sewer processes affect the quality of the wastewater and thereby the sewer itself, the subsequent treatment and the receiving water quality. The paper focuses on the interactions between the dry weather in-sewer chemical and microbial transformations of the wastewater and the corresponding processes in a downstream located treatment plant. A conceptual understanding of the sewer processes is crucial in this respect.
Biodegradability of wastewater – a method for COD-fractionation
Authors: Vollertsen J. , Hvitved-Jacobsen T.
Published: May 2018

Characterization of wastewater for simulation of in-sewer transformations can be carried out by interpretation of oxygen uptake rate measurements in combination with a conceptual model of the microbial transformations involved. This interpretation can be done by iterative procedures by solving the differential equations constituting the model or by the application of a more “manual” method – the latter being the topic of this paper. Examples where different wastewaters are characterized illustrate the method.
Dissolved oxygen in gravity sewers – measurement and simulation
Authors: Gudjonsson G. , Vollertsen J. , Hvitved-Jacobsen T.
Published: May 2018

Dissolved oxygen (DO) concentrations were during 2 months continuously measured in an intercepting sewer. Measurements were made upstream and downstream in a 3.6 km gravity sewer. DO showed significant diurnal variations mainly caused by changes in the organic matter composition of the wastewater. At low temperatures the gravity sewer was strictly aerobic. However, towards the end of the measuring campaign, DO concentrations decreased as temperature increased and the sewer became anaerobic part of the day. A conceptual model that takes into account bulk water and biofilm DO uptake as well as reaeration was used to simulate the DO measured. Using measurements from the upstream station as input, the model was calibrated to yield good validation results of the DO at the downstream station.
Estimation of pharmaceutical residues in primary and secondary sewage sludge based on quantities of use and fugacity modelling
Authors: Khan S.J. , Ongerth J.E.
Published: May 2018

A general procedure was developed for estimating the concentrations of pharmaceutical residues in fresh primary and secondary sewage sludge. Prescribed quantities coupled with information on the various excretion ratios of 20 pharmaceuticals and 2 of their metabolites enabled prediction of the overall rates of excretion into Australian sewage. Fugacity modelling was applied to predict concentrations of these residues in fresh primary and secondary sludge. Predicted concentrations ranged from 10−3 - 884 μg/L in primary sludge and 10-4 - 36 μg/L in secondary sludge. Overall rates of removal to sludges ranged from 1-39%. The accuracy of the model was verified by comparison to analytical data.
Sustainable rainwater management in the Emscher river catchment area
Authors: Becker M. , Raasch U.
Published: May 2018

The wastewater management system of the Emscher region is currently being radically restructured. The receiving waters currently surviving as open sewers are to be freed of their wastewater burden and reconstituted to a state as natural as possible, while the wastewater is to be routed underground to the treatment plants. Great importance is attached to the most natural possible rainwater management, in order to buffer extreme run-off situations in the watercourses and to minimize the costs for residential-area water management engineering. Rethinking, which in many cases percolates through only slowly, is necessary in many respects for this purpose. A contest has been set up in the Emscher catchment area in order to accelerate this in the existing residential areas. Seepage, decentralized retention, disconnection and discharge into bodies of water and watercourses have been financially supported. The results are presented and the further procedure deriving from them discussed.
Managing sewer solids for the reduction of foul flush effects – Forfar WTP
Authors: Fraser A.G. , Sakrabani R. , Ashley R.M. , Johnstone F.M.
Published: May 2018

In times of high sewer flow, conditions can exist which enable previously deposited material to be re-entrained back into the body of the flow column. Pulses of this highly polluted flow have been recorded in many instances at the recently constructed wastewater treatment plant (WTP) in Forfar, Scotland. Investigations have been undertaken to characterise the incoming flows and to suggest remedial measures to manage the quality fluctuations. Initial visits to the works and incoming pipes indicated a high degree of sediment deposition in the two inlet pipes. Analyses were carried out and consequently, changes to the hydraulic regime were made. Measurements of sediment level, sediment quality, wall slime and bulk water quality were monitored in the period following the remedial works to observe any improvements. Dramatic alterations in each of the determinands measured were recorded. Analyses were then undertaken to determine long term sediment behaviour and to assess the future usefulness of existing upstream sediment traps. It was concluded that with proper maintenance of the traps, the new hydraulic regime is sufficient to prevent further significant build up of sediment deposits and reduce impacts on the WTP. Further investigations made by North of Scotland Water Authority highlighted trade inputs to the system which may also have contributed to the now managed foul flush problem.
Microscopic versus macroscopic biomass models in activated sludge systems
Authors: Gujer W.
Published: May 2018

Today's models of activated sludge systems are based on average composition of biomass (macroscopic models). With the introduction of cell internal storage compounds (structured biomass) in ASM2 and ASM3 cell composition influences the kinetic behavior of activated sludge. Since the kinetics of most processes is not linear, adding up the behavior of individual cells (microscopic models) does not result in the same model prediction as obtained when predictions are made with average cell composition. Based on first simple computations with microscopic models which consider up to 100,000 individual bacteria, differences in model prediction are identified. It becomes clear that kinetic parameters for lumped, macroscopic models are system specific: whereas biomass from SBR systems yields kinetic parameters suited for application in microscopic models – biomass from continuous flow systems can only be used for the calibration of macroscopic models. Application of SBR models to continuous flow systems requires the use of microscopic models.
Processes and modeling of hydrolysis of particulate organic matter in aerobic wastewater treatment – a review
Authors: Morgenroth E. , Kommedal R. , Harremoës P.
Published: May 2018

Carbon cycling and the availability of organic carbon for nutrient removal processes are in most wastewater treatment systems restricted by the rate of hydrolysis of slowly biodegradable (particulate) organic matter. To date, the mechanisms of hydrolysis are not well understood for complex substrates and mixed populations. Most mathematical models use a simple one-step process to describe hydrolysis. In this article, mechanisms of hydrolysis and mathematical models to describe these processes in wastewater treatment processes are reviewed. Experimental techniques to determine mechanisms of hydrolysis and rate constants are discussed.
Evaluation of the accumulation of sediment and heavy metals in a storm-water detention pond
Authors: Färm C.
Published: May 2018

Accumulation of sediments and water quality were investigated in a wet storm-water detention pond in central Sweden. The drainage area surrounding the pond was covered by a section of highway and secondary roads. Sediment samples were collected from the pond and heavy-metal concentrations analysed subsequently in the laboratory. The depth of accumulated sediments was measured at several points around the pond. The investigation showed that during the 18 months that had passed since the pond was constructed, a 5–8 cm layer of sediments had accumulated near the inlet, and a 1.5 cm layer near the outlet of the pond. Storm water passing through the detention pond showed an average reduction rate of 26–84% for total metal content, 67% for total N, 78% for total P and 92% for COD.
Nutrient distribution in the Bosphorus and surrounding areas
Authors: Okuş E. , Aslan-Yilmaz A. , Yüksek A. , Taş S. , Tüfekçi V.
Published: May 2018

As part of a five years monitoring project “Water Quality Monitoring of the Strait of Istanbul”, February-December 1999 nutrient dynamics of the Black Sea-the Sea of Marmara transect are studied to evaluate the effect of discharges given by deep disposals. Through a one-year study, upper layer nutrient concentrations were generally under the effect of northwestern-shelf Black Sea originated waters. This effect was strictly observed in July, when the upper layer flow was the thickest. On the other hand, partly in November but especially in December the northwestern-shelf Black Sea originated water flow was a minimum resulting in similar concentrations in both layers. Nutrient fluctuations also affected the chlorophyll a and POC concentrations as parameters of productivity. The nutrient concentrations decreased with the effect of spring bloom and highest chlorophyll a values were detected in November at Strait stations that did not match to the Sea of Marmara values. This fact represents the time-scale difference between the Black Sea and the Sea of Marmara. On the contrary, high nutrient concentrations in the lower layer (especially inorganic phosphate), and therefore low N:P ratios reflect the effect of deep discharge. Vertical mixing caused by meteorological conditions of the shallow station (M3) under the effect of surface discharges resulted in homogenous distribution of nutrients. Nutrient concentrations of the stations affected by deep discharge showed that the two-layer stratification of the system did not permit the discharge mix to the upper layer.
A new process for the combined treatment of municipal wastewaters and landfill leachates in coastal areas
Authors: Yangin C. , Yilmaz S. , Altinbas M. , Ozturk I.
Published: May 2018

One of the most convenient methods for leachate control is to treat landfill leachates with domestic wastewaters. In this framework, a two-stage treatment system including anaerobic pre-treatment combined with a chemical post-treatment system such as ammonia stripping and/or Magnesium Ammonium Phosphate (MAP) precipitation can be comparable with a conventional secondary biological treatment. In this study, 2.5% and 2% of leachate by volume was mixed with domestic wastewater as the feed for the mesophilic Upflow Anaerobic Sludge Bed Reactor (UASBR). pH, feed strength and hydraulic retention time (HRT) were monitored for the evaluation of the performance of the anaerobic process. The HRT's varied from 0.76 to 0.52 d and 58% and 85% COD removal efficiencies were obtained at Organic Loading Rates (OLR) of 0.63 and 2 kg COD/m3.d respectively. The average biomass (VS) concentration in the reactor increased from 40 g/l to 50 g/l during the study. Effluents from the UASBR were further treated chemically either with lime for ammonia stripping or with MAP precipitation. MAP precipitation was applied both at the stoichiometric ratio (Mg:NH4:PO4 = 1:1:1) and above the stoichiometric ratio (Mg:NH4:PO4 = 1:1:1.3). Maximum NH4 removal of 66% was achieved at the pH of 9.3 at the stoichiometric ratio, whereas 86% NH4 removal was obtained at the pH of 9.3 above the stoichiometric ratio. Alternatively, ammonia stripping was applied either to the effluents directly taken from the anaerobic reactor or to the effluents to which MAP precipitation was applied stoichiometrically. Ammonia stripping was conducted for 24 h and 89% NH4 removal was observed at the end of 24 h. Consequently, this study indicates that anaerobic pre-treatment combined with chemical post-treatment (MAP) produced high quality of effluent comparable to the conventional biological treatment especially in terms of N and P levels.
Effect of loading rate and intermittent aeration cycle on nitrogen removal in membrane separation activated sludge process
Authors: Nagaoka H. , Kudo C.
Published: May 2018

The performance of the submerged membrane separation activated sludge process with intermittent aeration was investigated in a laboratory scale experiment by changing organic loading rate and intermittent aeration cycle. A rectangular PVC tank was used as an aeration tank, in which a flat-sheet type Micro-Filtration membrane made of poly-olefin with a pore size of 0.2 mm was submerged. Organic loading rate to the reactor was set at 0.3 and 0.8 g-TOC/L/day. C/N ratio in the feed was set at around 5.0 for every condition. Aeration cycle was changed from 10 min-10 min (aeration - stop) to 120 min-120 min in different organic loading conditions. Flux through the membrane was set at 0.25 m/day. Membrane fouling proceeded rapidly in 0.8 g-TOC/L/day conditions. However, when organic loading rate was 0.3 g-TOC/L/day, bacterial metabolic substances were degraded rapidly compared to the production, thereby decreasing viscosity in mixed liquor. Nitrogen removal rate was between 60% and 80% for 0.8 g-TOC/L/day loading, and between 50% and 65% for 0.3 g-TOC/L/day loading. And the nitrogen removal was highest in 40 min to 60 min aeration cycle conditions. Too short aeration cycle did not result in sufficiently long anoxic periods for denitrification while too long a cycle resulted in unnecessary anaerobic periods after depletion of nitrate. Intermittent aeration was effective also for decreasing viscosity in mixed liquor.
Municipal wastewater treatment in the anaerobic-aerobic baffled filter reactor at ambient temperature
Authors: Bodík I. , Kratochvíl K. , Herdová B. , Tapia G. , Gašpariková E.
Published: May 2018

This paper presents the pilot-scale experiments with anaerobic-aerobic treatment of municipal wastewater. As the anaerobic part of the pilot-scale system, the combination of the anaerobic baffled reactor and the anaerobic filter was used. The aerobic part of reactor was designed as an activated sludge system with the carrier of biomass (polypropylene cords). Two pilot-scale reactors (AN-I and AN-II) under real conditions were monitored. All technological parameters were identical in both reactors, but the AN-I reactor was inoculated with the psychrophilic digested sludge. The HRT in the anaerobic and aerobic parts of reactors were about 15 hours and 4 hours, respectively. The temperature in both reactors varied during the year from 4.5 to 23 °C. During the yearly operation time both systems removed all monitored parameters with relatively high efficiencies (COD - 78.6-83.0%, BOD5 - 92.5-94.0 and SS - 80.9-92.7%). The intensive nitrification process was observed during the whole year in both reactors (under average temperature of 5.9 °C in January 2000, too). The average removal of the NH4-N varied during the year from 46.4 to 87.3%. In both systems the effective denitrification process was observed, too. In the real conditions it is possible to operate such systems for a long time without removing excess sludge.
Integrated design of sewers and wastewater treatment plants
Authors: Vollertsen J. , Hvitved-Jacobsen T. , Ujang Z. , Talib S.A.
Published: May 2018

Sewer system design must be integrated with wastewater treatment plant design when moving towards a more sustainable urban wastewater management. This integration allows an optimization of the design of both systems to achieve a better and more cost-effective wastewater management. Hitherto integrated process design has not been an option because the tools to predict in-sewer wastewater transformations have been inadequate. In this study the WATS model - being a new and validated tool for in-sewer microbial process simulations - is presented and its application for integrated sewer and treatment plant design is exemplified. A case study on a Malaysian catchment illustrates this integration. The effects of centralization of wastewater treatment and the subsequently longer transport distances are addressed. The layout of the intercepting sewer is optimized to meet the requirements of different treatment scenarios.
Nitrate pollution in groundwater and strategies to reduce pollution
Authors: Shrestha R.K. , Ladah J.K.
Published: May 2018

The input-intensive rainfed tropical ecosystem, where wet season (WS) rice (Oriza sativa L.) – dry season (DS) diversified high-value upland crops like vegetables predominate, has resulted in a problem of a large leakage of N into the environment, thereby polluting the water. Excessive use of N fertilizer in high-value crops grown in DS is economically motivated. Out of twenty water sources evaluated in a watershed with a total area of 265 ha located in Magnuang, Ilocos Norte, Philippines, twelve had near or above the World Health Organization’s (WHO) NO3-N limit for drinking water of 10 ppm. Soil mineral N (upper 100 cm) observed in seven rice-sweet pepper (Capsicum annuum L.) farmers’ fields ranged from 111 to 694 kg ha-1 which decreased by 10 to 68% in plots with dry-to-wet (DTW) crops like indigo, indigo+mungo and corn. In fallow plots where mineral N was either maintained or increased, it showed movement to lower soil profiles demonstrating NO3 leaching without a crop. On average, maize (Zea mays L.) captured 176 kg N ha-1 and indigo (Indigofera tinctoria L.) 194 kg N ha-1. In both fallow and planted plots, mineral N declined to low levels at 100% water-filled pore spaces (WFPS) before rice transplanting. A strategy for including indigo plus maize as a N-catch crop is proposed to decrease NO3 leaching and maximize N use efficiency in a rice-sweet pepper cropping system.
Modelling and control of potable water chlorination
Authors: Pastre A. , Mulholland M. , Brouckaert C.J. , Buckley C.A. , Le Lann M.-V. , Roustan M. , Naidoo D. , Mabeer V.
Published: May 2018

The Umgeni Water Wiggins water treatment plant feeds the southern areas of Durban in South Africa and has a maximum treatment capacity of about 350 Ml/d. Two interconnected reservoirs at this facility hold treated water before it enters the distribution network. Because of the variable demand, the reservoir levels and residence times undergo considerable variation. This has a strong influence on the free chlorine concentration in the water leaving the reservoir, which should be 0.8 to 1.2 mg/l, to ensure an adequate disinfection potential within the network. This paper describes a model which accounts for the observed variations of chlorine concentration, and will form the basis of a predictive controller for the chlorine concentration in the outlet.
Study on self-purification capacity for organic pollutants in stagnant water
Authors: Saito M. , Magara Y. , Wisjnuprapto
Published: May 2018

Polluted water is abandoned or stored untreated in many places. Especially, small water bodies such as ditches, ponds, wastewater tanks, etc. have not yet well been considered. The self-purification stabilizes the wastewater, but oxygen supply limits the biodegradation process. In the natural environment, approximately 3 g oxygen can be dissolved per m2 per day if the water is completely deprived from dissolved oxygen; this is the magnitude of self-purification capacity. To improve the quality of polluted water with higher oxygen demand than natural reaeration capacity, enhanced aeration is required. The laboratory experiment disclosed that water trickling onto the water surface or shallow stirring of water less than 10 mm in depth increased the mass transfer rate significantly. At the same time, the methods were found more efficient than bubbling aeration of large-scale treatment plant in terms of energy input against oxygen supply. Though it is an efficient method, elaborate application will be necessary since the mass transfer rate is not as high as bubbling aeration.
Groundwater contamination assessment for sustainable water supply in Kathmandu Valley, Nepal
Authors: Khatiwada N.R. , Takizawa S. , Tran T.V.N. , Inoue M.
Published: May 2018

A study was carried out to assess the water quality situation of groundwater sources in Kathmandu Valley, Nepal. Groundwater has remained to be a major water supply source for a population of 1.5 million at present in the valley. The focus of this study was to evaluate the extent and sources of groundwater contamination. Water sampling was carried out in selected deep wells and shallow sources. The level of pollution was evaluated by comparing the water quality results with WHO guidelines. The major problems with the dug wells, hand pumps and spouts were found to be the elevated nitrate and mercury contents. The deep wells located on the central aquifer were found to have a serious threat of ammonia pollution. Deep wells were also found to have iron, manganese and mercury concentrations exceeding the guideline values. Multivariate statistical analysis was carried out to cluster the sampling sources and identify the common factors describing the potential sources and possible mechanisms associated with the contaminants. The results suggested that disintegration of the sediment organic matter under strong reducing environment leads to the origin of the unusual water qualities at the central confined aquifer. This process may be microbially mediated and occurs with the simultaneous reduction of species such as arsenic, iron, manganese and sulfate. Both natural and anthropogenic water quality problems were observed in the groundwater system of Kathmandu valley. Attention should be focused to consider distinct strategies to address these problems.
Toxicity and biodegradability of high strength/toxic organic liquid industrial effluents and hazardous landfill leachates
Authors: Naidoo V. , du Preez M. , Rakgotho T. , Odhav B. , Buckley C.A.
Published: May 2018

Industrial effluents and leachates from hazardous landfill sites were tested for toxicity using the anaerobic toxicity assay. This test was done on several industrial effluents (brewery spent grain effluent, a chemical industry effluent, size effluent), and several hazardous landfill leachates giving vastly different toxicity results. The brewery effluent, spent grain effluent and size effluent were found to be less toxic than the chemical effluent and hazardous landfill leachate samples. The chemical industry effluent was found to be most toxic. Leachate samples from the H:h classified hazardous landfill site were found to be less toxic at high concentrations (40% (v/v)) while the H:H hazardous landfill leachate samples were found to be more toxic even at low concentrations of 4% (v/v). The 30 d biochemical methane potential tests revealed that the brewery effluent, organic spent grain effluent and size effluent were 89%, 63%, and 68% biodegradable, respectively. The leachate from Holfontein hazardous landfill site was least biodegradable (19%) while the chemical effluent and Aloes leachate were 29% and 32% biodegradable under anaerobic conditions.
The effect of aeration and non-aeration time on simultaneous organic, nitrogen and phosphorus removal using an intermittent aeration membrane bioreactor
Authors: Ujang Z. , Salim M.R. , Khor S.L.
Published: May 2018

A laboratory-scale membrane bioreactor (MBR) was fed with synthetic wastewater to investigate the possibility of simultaneous removal of organic, nitrogen and phosphorus by intermittent aeration. The MBR consists of two compartments using a microfiltration membrane with 0.2 mm pore size and a surface area of 0.35 m2. Hydraulic retention time was set at 24 hours and solid retention time 25 days. MLSS concentration in the reactor was in the range of 2,500-3,800 mg/L. The MLSS internal recycling ratio was maintained at 100% influent flow rate. Intermittent aeration was applied in this study to provide an aerobic-anaerobic cycle. Three stages of operations were conducted to investigate the effect of aeration and non-aeration on simultaneous organic and nutrient removal. In Stage 1, time cycles of aeration and non-aeration were set at 90/150 min and 150/90 min in the first and second compartment, the removal efficiency was 97%, 94% and 70% for COD, nitrogen and phosphorus respectively. In Stage 2, time cycles of aeration and non-aeration were set at 60/120 min and 120/60 min in the first and second compartment, the removal efficiency was 97%, 96% and 71% for COD, nitrogen and phosphorus respectively. In Stage 3, time cycles of aeration and non-aeration were set at 120/120 min and 120/120 min in compartment 1 and 2, the removal efficiency was 98%, 96% and 78% for COD, nitrogen and phosphorus respectively. Results show that longer non-aeration time in the second compartment provided better performances of biological phosphorus removal.
High salinity wastewater treatment using yeast and bacterial membrane bioreactors
Authors: Dan N.P. , Visvanathan C. , Polprasert C. , Ben Aim R.
Published: May 2018

Two laboratory-scale membrane bioreactor systems were investigated to treat high salinity wastewater containing high organic (5,000 mg/L COD) and salt content (32 g/L NaCl), namely: (1) the Yeast Membrane Bioreactor (YMBR) and; (2) Yeast pretreatment followed by Bacterial Membrane Bioreactor (BMBR). In the YMBR system, experimental runs were conducted with a mean biomass concentration of 12 g MLSS/L. Here the maximum COD removal rate of 0.93 g COD/g MLSS.day was obtained at F/M of 1.5 g COD /g MLSS.d. Whereas, the BMBR system was operated with a biomass concentration of up to 25 g MLSS/L, resulting in maximum COD removal rate of 0.32 kg COD /kg MLSS.day at F/M ratio of 0.4. In comparison to BMBR, YMBR could obtain higher COD removal rate at higher organic loading, indicating the potential of a yeast reactor system to treat high salinity wastewater containing high organic concentration.

Transmembrane pressure in BMBR was progressively increased from 2 to 60 kPa after 12 d, 6 d and 2 d at a hydraulic retention time (HRT) of 14 h, 9 h and 4 h, with average biomass concentration of 6.1, 15 and 20 g MLSS/L, respectively. Whereas the transmembrane pressure in YMBR has increased from 2 to 60 kPa only after 76 days of operation, with an average biomass concentration of 12 MLSS/L and an operating HRT range of 5-32 h.
Real-time water quality monitoring and regression analysis to estimate nutrient and bacteria concentrations in Kansas streams
Authors: Christensen V.G. , Rasmussen P.P. , Ziegler A.C.
Published: May 2018

An innovative approach currently is underway in Kansas to estimate and monitor constituent concentrations in streams. Continuous in-stream water-quality monitors are installed at selected U.S. Geological Survey stream-gaging stations to provide real-time measurement of specific conductance, pH, water temperature, dissolved oxygen, turbidity, and total chlorophyll. In addition, periodic water samples are collected manually and analyzed for nutrients, bacteria, and other constituents of concern. Regression equations then are developed from measurements made by the water-quality monitors and analytical results of manually collected samples. These regression equations are used to estimate nutrient, bacteria, and other constituent concentrations. Concentrations then are available to calculate loads and yields to further assess water quality in watersheds. The continuous and real-time nature of the data may be important when considering recreational use of a water body; developing and monitoring total maximum daily loads; adjusting water-treatment strategies; and determining high constituent concentrations in time to prevent adverse effects on fish or other aquatic life.
Impact of non-detects in water quality data on estimation of constituent mass loading
Authors: Kayhanian M. , Singh A. , Meyer S.
Published: May 2018

Often, fractions of stormwater constituents are not detected above laboratory reporting limits and are reported as non-detect (ND), or censored data. Analysts and stormwater modelers represent these NDs in stormwater data sets using a variety of methods. Application of these different methods results in different estimates of constituent mean concentrations that will, in turn, affect mass loading computations. In this paper, different methods of data analysis were introduced to determine constituent mean concentrations from water quality datasets that include ND values. Depending on the number of NDs and the method of data analysis, differences ranging from 1 to 70 percent have been observed in mean values. Differences in mean values were, as shown by simulation, found to have significant impacts on estimations of constituent mass loading.
Effect of important operational parameters on performance of coarse pore filtration activated sludge process
Authors: Alavi Moghaddam M.R. , Satoh H. , Mino T.
Published: May 2018

A coarse pore filter can be applied inside the aeration tank instead of sedimentation tank for liquid separation from the sludge. It has pores, which are irregular in shape, and much bigger than micro-filtration membrane pores in size. The objective of the study was to investigate the effect of important operational parameters such as flux, aeration intensity, and solid retention time (SRT) on the performance of the coarse pore filtration activated sludge process. The effect of these parameters was studied in laboratory scale experiments. It was found that the flux had a significant role in the effluent quality of this system. The effluent SS and turbidity were not changed significantly at different aeration intensities. Three SRTs, 10, 30 and longer days (without excess sludge) were used for three reactors to check the effect of this parameter on the system performance. The results of the reactors with SRTs about 10 and 30 days have shown very good effluent quality without any filter clogging for more than 4 months operation. For the reactor with long SRT, the filter clogging was observed after about 80 days of operation, which caused the increase of the operation pressure and deterioration in the effluent quality for a few days.