Pilot Wastewater Treatment Plant Research Articles

The use of quadrupole-time-of-flight mass spectrometer for the elucidation of diclofenac biotransformation products in wastewater

The work presented herein discusses the potential of liquid chromatography–quadrupole-time-of-flight mass spectrometry (QqToF–MS) for the chemical structure elucidation of pharmaceutical degradation products (DPs). The model compound, the nonsteroidal anti-inflammatory drug diclofenac was subjected to microbiological transformation in a laboratory scale pilot wastewater treatment plant (WWTP) and its transformation products were detected in the outlet samples. Their chemical structures were elucidated using the principal features of the instrument, i.e. high resolution, accurate mass and MS/MS capability. A hydroxy-diclofenac, a benzoquinone imine derivative and a nitro analogue of diclofenac were successfully identified. The final structural elucidation of the fourth transformation product was not successful. Overall, the study emphasises the capabilities and potential of quadrupole-time-of-flight mass spectrometer showing it to be a powerful tool in both structure elucidation and confirming the identity of environmental contaminants.

Examining the biodegradation of endocrine disrupting bisphenol A and nonylphenol in WWTPs

The aim of this work was to examine biodegradation of the endocrine disrupting chemicals bisphenol A (BPA) and nonylphenol (NP) in activated sludge. Experiments were performed in a pilot wastewater treatment plant (WWTP) in Copenhagen, Denmark. During standard operation the BPA concentration was halved whereas the NP concentration was unchanged. Step-addition experiments showed that biomass adaptation to increased BPA and NP concentrations took 10 to more than 40 days depending on temperature, hydraulic retention time, and pre-exposure of the biomass. Mass-balance experiments showed that above 99% of the dosed BPA and 90% of the dosed NP is removed by biodegradation at steady-state. Batch experiments showed that BPA biodegradation occur solely under aerobic conditions. The work is believed to add vital knowledge to our understanding of parameters and processes governing biodegradation of EDCs in WWTPs.

Effects of environmental conditions on the nitrifying population dynamics in a pilot wastewater treatment plant

The effect of environmental conditions, especially ammonium concentration, on community composition and nitrification activity of nitrifying bacterial biofilms in a pilot wastewater treatment plant was examined. A decreasing ammonium gradient was created when four aerated tanks with suspended carrier material were serially fed with wastewater. Community composition was analysed using fluorescence in situ hybridization (FISH) probes as well as partial 16S rRNA and amoA gene analysis using polymerase chain reaction-denaturating gradient gel electrophoresis (PCR-DGGE) and sequencing. Fluorescence in situ hybridization probes identified at least five ammonia-oxidizing bacterial (AOB) and two nitrite-oxidizing bacterial (NOB) populations. A change in nitrifying community was detected in the tanks, indicating that ammonium was an important structuring factor. Further, we found support for different autoecology within the Nitrosomonas oligotropha lineage, as at least one population within this lineage increased in relative abundance with ammonium concentration while another population decreased. Absolute numbers of AOB and NOB growing in biofilms on the carriers were determined and the cell specific nitrification rates calculated seemed strongly correlated to ammonium concentration. Oxygen could also be limiting in the biofilms of the first tank with high ammonium concentrations. The response of the nitrifying community to increased ammonium concentrations differed between the tanks, indicating that activity correlates with community structure.

Removal of pharmaceutical residues in a pilot wastewater treatment plant

Concern is growing over the contamination of the environment with pharmaceutical residues, among which non-steroidal anti-inflammatory drugs (NSAIDs) are one of the most abundant groups. Their widespread appearance in the aquatic environment is because of their high consumption and their incomplete removal during wastewater treatment. Because effective operation of wastewater-treatment plants is important for minimising the release of xenobiotic compounds, for example pharmaceutical products, into the aquatic environment, our study focuses on removal of commonly used NSAIDs (ibuprofen, naproxen, ketoprofen, diclofenac) and clofibric acid in a specially designed small-scale pilot wastewater treatment plant (PWWTP). This study shows that, except for diclofenac, steady-rate removal of NSAIDs over a two-year monitoring period has been achieved. Elimination of the compounds in the PWWTP was >or=87% for ibuprofen, naproxen and ketoprofen but only 49-59% for diclofenac. We also studied clofibric acid. Results after one month of operation revealed 30% elimination with no sign of adaptation by the biomass. Also described are degradation products of diclofenac, which we were able to identify because of the similarity of their mass spectra with those in the NIST library and by comparing the retention times of different compounds. Although the structures of these compounds were confirmed with a high probability (99%), we still need to compare the fragmentation of authentic compounds with degradation products formed under our experimental conditions. Degradation products of ibuprofen, naproxen, ketoprofen, and clofibric acid were found but these must be identified by use of high-resolution mass spectrometry and analysis of authentic compounds.

A NEURAL NETWORK MODEL FOR CONTROL OF WASTEWATER TREATMENT PROCESSES

This paper discusses the development of a neural network model for the prediction of the influent disturbances, which ultimately affect the activated sludge process. Neural networks are particularly suited to problems where there is no clear understanding of the processes and the complex inter-relationship between variables. The historical data used for training and testing the neural network is actual plant data obtained from a municipal plant and weather data for the same time periods. The result of the predicted influent disturbance is used in the control of the dissolved oxygen (DO). The results are applied to a pilot wastewater treatment plant located at the Cape Peninsula University of Technology (CPUT). The number of and the type inputs are varied to find an optimal model in order to predict the Chemical Oxygen Demand (COD), Total Kjeldahl Nitrogen (TKN) and the flowrate. Three different dynamic multilayer perceptron (MLP) feed-forward neural network models are developed for the influent disturbances of COD, TKN and flowrate respectively.

Degradability of five aromatic compounds in a pilot wastewater treatment system

Abstract Purified terephthalic acid-manufacturing wastewater was treated aerobically with the microbial fusant Fhhh in the carrier activated sludge process at a pilot wastewater treatment plant. Biodegradability of p-toluic acid (p-Tol), benzoic acid (BA), 4-carboxybenzaldehyde (4-CBA), phthalic acid (PA) and terephthalic acid (TA) was monitored. The TOC and COD loading rate of suspended solids (SS) in the sludge were 0.53 g TOC g SS−1 d−1 and 1.79 g COD g SS−1 d−1, respectively. There was significant positive correlation (P PA>4-CBA>TA>p-Tol. The prospect of using MnP-SA to predict the removal rate for the five aromatics is discussed.

Comparison of Two Model Concepts for Simulation of Nitrogen Removal at a Full-Scale Biological Nutrient Removal Pilot Plant

The experimental studies conducted at the Hanover-Gummerwald pilot wastewater treatment plant (WWTP) focused on minimizing nitrogen loads discharged during stormwater events. The data collected during the plant operation were used for a long-term process simulation. The aim of this study was to compare predictive capabilities of two different mechanistic models (ASM2d and ASM3P) in terms of nitrogen removal. The influent wastewater composition was generated using on-line measurements of only three parameters (COD, N–N H4+ , P–P O4 3− ) and the model predictions were primarily compared with on-line data (concentrations of N–N H4+ , N–N O3− ) originating from the aerobic zone of the bioreactor. The simulation results confirmed the experimental data concerning the capabilities of the system for handling increased flows during stormwater events. The predicted peaks of N–N H4+ at the line with the quadruple dry weather flow rate were normally exceeding 8 g N∙ m−3 (similar to the observations), whereas no (or m...

Modeling of pore blocking and cake layer formation in membrane filtration for wastewater treatment

Membrane filtration in municipal and industrial wastewater treatment is a technology being increasingly employed to enhance the quality of purified water, increase the productivity of existing plants, and build smaller, yet more effective purification processes. Barrier to a breakthrough of the technology is the increased operational cost due to fouling and membrane replacement. Simulation studies with rigorous process models are a powerful tool to increase the understanding of the process and its decisive characteristics in order to design optimal processes and efficient operational strategies. In this paper, two enhancements of existing modeling approaches are proposed. One is taking into account the adhesive forces between the particles and the membrane surface, which indeed strongly effect cake layer formation and back flushing efficiency. The other is assessing the decisive influence of particle and membrane pore size distributions on both cake layer formation and pore blocking and their mutual dependencies. Both phenomena are essential characteristics which need to be considered for a reliable prediction of process behavior. The model is successfully tested in simulation studies and compared to experimental data from a pilot wastewater treatment plant with submerged hollow fiber membranes.

Fault-Tolerant soft PLC control using shadow processes

This paper deals with an efficient and fault-tolerant control system for the pilot wastewater treatment plant operated at the CSCI group. A SolfPLC, rather than a standard industrial PLC, is used because it provides much more flexibility when performing experimental studies. On the other hand, this is a biotechnological pilot-plant and it is imperative to provide round-the-clock and fault-tolerant control. Otherwise, the biomass may degrade rapidly, thus making it unusable. The presented control system consists of a main program running on a PC computer and a shadow program running on the FieldPoint real-time controller. The shadow program monitors the main program and if a failure is sensed, it takes over control of the process. Other mechanisms are implemented in order to ensure a proper cooperation between the main and the shadow program.

Hybrid control system for pilot wastewater treatment plant

Abstract This paper deals with a design method of the digital all-pass filter designated for equalization of the group delay frequency response of the digital filter. This method is based on usage of evolutionary algonthm, the Differentia, Evolution algorithm in particular. We are able to propose such equalizers to be obtained equal-ripple group delay frequency response in the pass-band of the low-pass filter. Moreover. the mefhod allows to include all-pass filter coefficients quantization process to the design procedure as to implement the proposed digital all-pass filter on a fixed-point dlgital signal processor. The procedure works automatically without an input estimation. The method is presented on solving practical examples.

TOWARDS AN INTEGRATED CO-OPERATIVE SUPERVISION SYSTEM FOR ACTIVATED SLUDGE PROCESSES OPTIMISATION

This paper deals with the design of an integrated co-operative supervision system to optimise activated sludge wastewater treatment. For this purpose a biological wastewater treatment pilot plant, suitable for industrial up scaling and composed of a biological reactor, a settler, sludge recirculation and aeration systems, has been carried out. The reactor configuration is adjustable to treat both urban and industrial wastewater. The pilot plant scale allows to reproduce industrial hydrodynamics and is illustrated by RTD (Residence Time Distribution) measurements. The supervisory system includes instrumentation and industrial supervisor. The integrated co-operative supervision approach emphases the importance of process behavior anticipation. Information for the human operator will be extracted from a suitable model and a state estimator, which results are presented.

BIOLOGICALLY MEDIATED PHOSPHORUS PRECIPITATION IN WASTEWATER TREATMENT WITH MICROALGAE

A lab-scale continuous microalgal culture was grown on sterile-filtered wastewater in order to clarify the phosphorus removing mechanisms in a microalgal treatment step that treats residual phosphorus from a hydroponic wastewater treatment pilot plant. The phosphorus assimilation was dependent on algal biomass production, whereas the chemical precipitation was dependent on phosphorus load, i.e. an increase in average precipitation rate with decreased hydraulic retention time was observed. The chemical precipitation was mainly a result of the increased pH, which was biologically mediated by the photosynthesising algae. The precipitate was composed of a calcium phosphate with magnesium included, magnesium hydroxide and calcite. A significant nitrogen removal was also experienced, which implies that the microalgal wastewater treatment is appropriate both for phosphorus and nitrogen removal.

Sequencing Batch Reactor Versus Continuous Flow Process for Pilot Plant Research on Activated Sludge

The objective of this article is to compare the advantages and disadvantages of the sequencing batch reactor (SBR) versus the more conventional continuous flow reactor (CFR) setup for pilot plant studies. The SBR process can offer many superior features for research applications. The control of operational conditions is more reliable, precise and versatile. Data collection by sampling and on-line sensors is made easier, and results are more representative. Kinetic and settling tests that need to be conducted in a separate bench-scale reactor for a CFR can be carried out directly within an SBR pilot plant. Even routine data contains more information than obtained from a CFR, since each SBR cycle is equivalent to a batch treatment experiment. The drawbacks of an SBR pilot plant mainly concern the transferability of certain kinetic and settling results to (full scale) completely mixed flow-through reactors, and some experimental limitations due to the cyclic operation. It is expected that this comparison will support the decision of research teams intending to design a wastewater treatment pilot plant. If an SBR process is selected, some specific design recommendations are given at the end of this paper to make sure that its potential advantages are realized.

Laundry wastewater treatment using coagulation and membrane filtration

This paper presents the results obtained from laundry wastewater treatment using conventional methods namely precipitation/coagulation and the flocculation process with adsorption on granular-activated carbon (GAC) and an alternative method, membrane filtrations, namely ultrafiltration (UF) and reverse osmosis (RO). Chemical analyses showed that parameter values of untreated wastewater like temperature, pH, sediment substances, total nitrogen and phosphorous, COD, BOD 5, and the amount of anion surfactants had been exceeded in regard to Slovenian regulation. These regulations can be used as requirements for wastewater reuse and make treated wastewater an available source for the existing water supply. The study of conventional treatment was based on a flocculation with Al 2(SO 4) 3·18H 2O and adsorption on GAC. Membrane filtrations were studied on a pilot wastewater treatment plant: ultrafiltration (UF) and reverse osmosis (RO) units. The membranes used in this experiment were ceramic UF membrane and spiral wounded – polyethersulfone – RO membranes. The quality of the wastewater was improved by both methods and the specifications of a concentration limit for emission into water were confirmed. The disadvantage of GAC is that there is no possibility of any kind of selection, which is essential for recycling and re-use, while permeate coming from RO met the required regulation as well as requirements for reusing in washing process. However, the economical analyses showed that the membrane filtrations are more expensive compared to the GAC treatment process.

Abstraction of continuous system trajectories into timed automata

This paper deals with the representation of continuous system dynamics into a timed discrete-event formalism to the end of system analysis. The continuous model of the system is first approximated using intervals and then translated into the timed automata formalism by comparison with thresholds defined on the state variables’ domains. The detection of thresholds crossing is characterised by two time instants corresponding respectively to the earliest and latest crossing dates. This approach is briefly illustrated with real data obtained from a 1 m wastewater treatment pilot plant.

Biological nitrogen and organic matter removal from tannery wastewater in pilot plant operations in Ethiopia.

The objective of this study was to set-up a pilot plant and to evaluate its effectiveness for biological nitrogen and organic matter removal from tannery wastewater in Ethiopia. A pilot wastewater treatment plant consisting of a predenitrification-nitrification process was constructed and operated for 6 months. This was fed with a raw tannery wastewater obtained from the Modjo Tannery located 70 km south of the capital, Addis Ababa. Up to 98% total nitrogen and chemical oxygen demand, and 95% ammonium nitrogen removal efficiencies were achieved in the system. The average effluent ammonium nitrogen ranged from 8.4 mg l(-1) to 86.0 mg l(-1), whereas the average effluent for nitrate nitrogen ranged from 2.9 mg l(-1) to 4.4 mg l(-1). The average values of denitrification and nitrification rates determined by nitrate and ammonium uptake rates (NUR and AUR) were 8.0 mg NO3-N [g volatile suspended solids (VSS)](-1) h(-1) and 5.4 mg NH4-N (g VSS)(-1) h(-1), respectively, demonstrating that the treatment processes of the pilot plant were effective. Further studies of the effect of chromium III on AUR showed 50% inhibition at a concentration of 85 mg l(-1), indicating that this metal was not causing process inhibition during performance operations. Thus, the predenitrification-nitrification process was found to be efficient for simultaneous removal of nitrogen and organic substrates from tannery wastewaters.

Wastewater treatment after reactive printing

Membrane filtration of wastewater after textile printing with reactive dyes is described. The wastewater from a Slovenian factory, whose output is approx. 80% reactive dyes printed and dyed on cotton, was studied. In particular, the presence of urea, sodium alginate, oxidation agent and reactive dyes, used for the printing paste preparation, in the wastewater was studied. Chemical analyses of actual, non-purified, wastewater showed that many Slovenian regulations were exceeded. The study of membrane filtration is based on a pilot wastewater treatment plant: ultrafiltration (UF) and reverse osmosis (RO) units. The quality of the wastewater was improved by ultrafiltration, but its effluent still does not conform to the specification of concentration limits for emission into water. Permeate coming from RO meets the required specification and, therefore, could be re-used in the washing process of printed textiles.

Identification of Efficient Denitrifying Bacteria from Tannery Wastewaters in Ethiopia and a Study of the Effects of Chromium III and Sulphide on Their Denitrification Rate

In order to identify potential microorganisms with high denitrifying capacity from tannery wastewaters, 1000 pure cultures of bacterial isolates from Modjo Tannery Pilot and Ethio-tannery wastewater treatment plants (WWTP), in Ethiopia, were investigated. Twenty-eight isolates were selected as efficient denitrifiers. These were Gram-negative rods, oxidase and catalase positive denitrifying organisms. The 28 denitrifying strains were further classified according to their biochemical fingerprints into three different phylogenetic groups (BPT1, BPT2 and BPT3) and seven singles. Isolates B79T, B11, B12, B15, B28 and B38 belonging to the BPT3 cluster were found to be the most efficient denitrifying bacteria. All phenotypic studies, including cellular fatty acid profiles, showed that the 6 BPT3 isolates were closely related to each other. The 16S rRNA partial sequence analysis of type strain B79T(CCUG 45880) indicated a sequence similarity of 99% to Brachymonas denitrificans JCM9216 (D14320) in the β-subdivision of proteobacteria. Further studies of the effects of chromium III and sulphide on the six Brachymonas denitrificans strains indicated that denitrification by the isolates were inhibited 50% at concentrations of 54 and 96 mg/l, respectively. The efficient isolates characterized in this study are of great value because of their excellent denitrifying properties and relatively high tolerance to the concentrations of toxic compounds (70 mg chromium/l and 160 mg sulphide/l) prevailing in tannery wastewaters.

Knowledge-based unmanned automation and control systems for the SBR wastewater treatment process

Wastewater treatment processes are usually located in rural seclusion. we designed an unmanned and automated control system for a sequencing batch reactor (SBR) wastewater treatment pilot plant. The pilot plant was constructed in the countryside, a small distance from a large city. Networks and wireless modules were employed for data transmission. A local controller was installed in the SBR pilot plant as a client, and a monitoring system was located in another place as a server. The communication system consisted of an asymmetric digital subscriber line (ADSL) network and a code division multiple access (CDMA) module. A remote control and monitoring system were constructed in a laboratory in the city. We describe a fuzzy inference system which was constructed with the operator's assistance, and acquired sensor data to determine the threshold and influent.

A New Technique Using Headspace Gas Monitoring to Determine Carbon Source Addition in a BNR Process

A new method was developed using the carbon dioxide detected in the headspace of a batch reactor to determine the carbon source addition in the biological nutrient removal (BNR) process. The activated sludge used in this study was taken from the University of British Columbia (UBC) Wastewater Treatment Pilot Plant aerobic tanks undergoing simplified UCT process. Experiments showed that detectable changes of carbon dioxide concentration in the headspace reflected the acetate utilization in the anaerobic condition, i.e. the P release reaction. In the sodium acetate addition cases, the elapsed time (E Time) of carbon dioxide evolution rate changes was proportional to the amount of acetate added in solution. Results were successfully used to estimate the amount of acetate added in tests. This new methodology was also capable of estimating the amount of VFAs recovered from the thermophilic aerobic digestion (TAD) supernatant.This on-line “E Time” monitoring approach has the potential to optimize the carbon source addition in BNR processes.