Wastewater Treatment Systems (wastewater + treatment_system)

Distribution by Scientific Domains

Selected Abstracts

Investigation of an onsite wastewater treatment system in sandy soil: Site characterization and fate of anionic and nonionic surfactants

Allen M. Nielsen
Abstract This study reports on the fate of linear alkylbenzene sulfonate (LAS), alcohol ethoxylate (AE), and alcohol ether sulfate (AES) surfactants in a home septic system near Jacksonville (FL, USA) that has been used since 1976. The drainfield at this site resides in fine sand (<6% silt and clay) with an unsaturated zone that ranges from 0 to 1.3 m. During the wettest times of the year, it is likely that effluent from the septic system passes directly into the groundwater without exposure to an unsaturated zone of soil. Groundwater was collected during two sampling events, representing seasonal high and low groundwater table levels, and analyzed for the surfactants LAS, AES, and AE. During the wet season, the unsaturated zone was approximately 0.01 m beneath the drainfield. During the dry season, the unsaturated zone was about 0.4 m below the drainfield. Alcohol ethoxylate was not detected in any groundwater samples during either sampling. Alcohol ether sulfate was not found in the dry season sampling, but traces of AES had migrated downgradient about 4.7 m horizontally and 1.8 m vertically in the wet season. Linear alkylbenzene sulfonate was detected in some dry season samples and had moved downgradient some 11.7 m horizontally and 3.7 m vertically in the wet season. These observations demonstrate that these surfactants were removed to a great extent; otherwise, they would have traveled more than 260 m downgradient, which is the calculated distance that a conservative tracer like bromide would have moved downgradient over the life of the system. The most likely removal mechanisms for these surfactants were biodegradation and sorption. Therefore, this study indicates that LAS, AE, and AES are readily removed from groundwater in soils below septic system drainfields even in situations with minimal unsaturated soil zones. [source]

Carbon-nitrogen-phosphorus removal and biofilm growth characteristics in an integrated wastewater treatment system involving a rotating biological contactor

Angelo H. Cabije
Abstract A new rotating biological contactor-packed media technology (RBC-PMT) is locally innovated using light polyethylene Amazon screen material as disc media. A single-stage co-current fed of this type, which is connected with a series of equalization tanks as an integrated wastewater treatment system (IWWTS), showed good carbon-nitrogen-phosphorus (C-N-P) removal and unveiled biofilm growth characteristics noteworthy for treating pollutants in wastewater. The equalization tanks approached facultative anaerobic conditions while the RBC-PMT exhibited a completely aerated system, both with a slightly alkaline pH, whose temperatures are ranging from 21 to 24 C, and both performed as biological nutrient removal systems. The combined nutrient removal efficiency at high organic loading rate (HOLR) and low organic loading rate (LOLR) showed fair chemical oxygen demand (COD) removal at 65.68 and 67.89%, respectively. Nitrate-nitrogen removal demonstrated good removal at 79.17% at HOLR and 83.43% at LOLR. There was excellent phosphate-phosphorus removal determined at 91.64 and 94.35% at high and low OLRs, respectively. This indicates that increasing the organic loading rate decreases the C-N-P removal in the IWWTS. Biofilm growth was characterized by the selection and survival of microorganisms present under aerobic environmental conditions in the RBC-PMT system and their respective metabolism in removing C-N-P substrates. Yeasts, coliform bacteria particularly E. coli, Cyanobacteria, and benthic diatoms were dominant microorganisms found upon oil-immersion microscopy. Protozoans and algae including Chlorococcum, Chlorella, Diatoma, Tribonema, Oscillatoria, Euglena, and other motile rotifiers were also dominantly found in the biofilm samples. Biofilm growth is observed and its average thickness was measured to be 7.71 m at HOLR and 2.81 m at LOLR. Thicker biofilm at HOLR has caused the reduced rate of diffusion of the microorganisms and their metabolic products as manifested by the low C-N-P removal during HOLR. Copyright 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source]

Analysis of a Microbial Community Oxidizing Inorganic Sulfide and Mercaptans

Kathleen E. Duncan
Successful treatment of refinery spent-sulfidic caustic (which results from the addition of sodium hydroxide solutions to petroleum refinery waste streams) was achieved in a bioreactor containing an enrichment culture immobilized in organic polymer beads with embedded powdered activated carbon (Bio-Sep). The aerobic enrichment culture had previously been selected using a gas mixture of hydrogen sulfide and methyl mercaptan (MeSH) as the sole carbon and energy sources. The starting cultures for the enrichment consisted of several different Thiobacillispp. (T. thioparus, T. denitrificans, T. thiooxidans, and T.neopolitanus), as well as activated sludge from a refinery aerobic wastewater treatment system and sludge from an industrial anaerobic digester. Microscopic examination (light and SEM) of the beads and of microbial growth on the walls of the bioreactor revealed a great diversity of microorganisms. Further characterization was undertaken starting with culturable aerobic heterotrophic microorganisms (sequencing of PCR-amplified DNA coding for 16S rRNA, Gram staining) and by PCR amplification of DNA coding for 16S rRNA extracted directly from the cell mass, followed by the separation of the PCR products by DGGE (denaturing gradient gel electrophoresis). Eight prominent bands from the DGGE gel were sequenced and found to be closest to sequences of uncultured Cytophagales (3 bands),Gram-positive cocci (Micrococcineae), , proteobacteria (3 bands), and an unidentified , proteobacterium. Culturable microbes included several genera of fungi as well as various Gram-positive and Gram-negative heterotrophic bacteria not seen in techniques using direct DNA extraction. [source]

A MATLAB toolbox for solving acid-base chemistry problems in environmental engineering applications

Chetan T. Goudar
Abstract A MATLAB toolbox incorporating several computer programs has been developed in an attempt to automate laborious calculations in acid-base chemistry. Such calculations are routinely used in several environmental engineering applications including the design of wastewater treatment systems and for predicting contaminant fate and transport in the subsurface. The computer programs presented in this study do not replace student thinking involved in formulating the problem solving strategy but are merely tools that simplify the actual problem solving process. They encompass a wide variety of acid-base chemistry topics including equilibrium constant calculations, construction of distribution diagrams for mono and multiprotic systems, ionic strength and activity coefficient calculations, and buffer index calculations. All programs are characterized by an intuitive graphical user interface where the user supplies input information. Program outputs are either numerical or graphical depending upon the nature of the problem. The application of this approach to solving actual acid-base chemistry problems is illustrated by computing the pH and equilibrium composition of a 0.1 M Na2CO3 system at 30C using several programs in the toolbox. As these programs simplify lengthy computations such as ionization fraction and activity coefficient calculations, it is hoped they will help bring more complicated problems to the environmental engineering classroom and enhance student understanding of important concepts that are applicable to real-world systems. The programs are available free of charge for academic use from the authors. 2005 Wiley Periodicals, Inc. Comput Appl Eng Educ 13: 257,265, 2005; Published online in Wiley InterScience (www.interscience.wiley.com); DOI 10.1002/cae.20051 [source]

Industrial wastewater treatment in a membrane bioreactor: A review

B. Marrot
Abstract This paper provides a detailed literature review of wastewater treatment in a membrane bioreactor process (MBR) with special focus on industrial wastewater treatment. MBR systems are compared with conventional wastewater treatment systems. The characteristics of the bioreactor treatment process (biomass concentration and floc size, organic and mass loading rates, etc.) are examined. The membrane separation of microorganisms from the treated wastewater is discussed in detail. Problems of membrane fouling and membrane washing and regeneration, linked to activated sludge characteristics, are examined. 2004 American Institute of Chemical Engineers Environ Prog, 23: 59,68, 2004 [source]

Enhanced process monitoring for wastewater treatment systems

Chang Kyoo Yoo
Abstract Wastewater treatment plants (WWTPs) remain notorious for poor data quality and sensor reliability problems due to the hostile environment, missing data problems and more. Many sensors in WWTP are prone to malfunctions in harsh environments. If a WWTP contains any redundancy between sensors, monitoring methods with sensor reconstruction such as the proposed one can yield a better monitoring efficiency than without a reconstruction scheme. An enhanced robust process monitoring method combined with a sensor reconstruction scheme to tackle the sensor failure problems is proposed for biological wastewater treatment systems. The proposed method is applied to a single reactor for high activity ammonia removal over nitrite (SHARON) process. It shows robust monitoring performance in the presence of sensor faults and produces few false alarms. Moreover, it enables us to keep the monitoring system running in the case of sensor failures. This guaranteed continuity of the monitoring scheme is a necessary development in view of real-time applications in full-scale WWTPs. Copyright 2007 John Wiley & Sons, Ltd. [source]

Assessment of high density of onsite wastewater treatment systems on a shallow groundwater coastal aquifer using PCA

Steven Carroll
Abstract Onsite wastewater treatment systems are common throughout the world, including Australia, with approximately 17% of the Australian population relying on these systems to treat and ultimately dispose of wastewater. Systems which are properly sited, designed and managed are an effective way of providing the necessary treatment of wastewater. However, incidence of onsite system failure is common, and this is further compounded in areas where high densities of systems are established. The density of systems is not appropriately assessed in the siting and design stage. Various factors, such as site and soil characteristics and climate, can influence the treatment efficiency, and this is more critical in high density areas. Principal component analysis was used for assessing chemical and microbiological data from shallow groundwater below a high density of onsite treatment systems. The results of this study confirmed that high system densities can significantly impact shallow groundwater systems. Additionally, changes in spatial and climatic conditions, as well as the type of onsite system, can also influence the quality of groundwater. Copyright 2004 John Wiley & Sons, Ltd. [source]

Development and application of a fatty acid based microbial community structure similarity index

Alan Werker
Abstract This article presents an index of similarity that has application in monitoring relative changes of complex microbial communities for the purpose of understanding the impact of community instability in biological wastewater treatment systems. Gas chromatographic data quantifying microbial fatty acid esters extracted from biosolids samples can be used to infer the occurrence of changes in mixed culture community structure. One approach to rapidly assess the relative dissimilarity between samples is to calculate a similarity index scaled between 0 and 1. The many arbitrary scales that are associated with the available calculation methods for similarity indices limits the extent of application. Therefore, a specialized index of similarity was derived from consideration of the measurement errors associated with the chromatographic data. The resultant calculation method provides a clear mechanism for calibrating the sensitivity of the similarity index, such that inherent measurement variability is accommodated and standardization of scaling is achieved. The similarity index sensitivity was calibrated with respect to an effective gas chromatographic peak coefficient of variation, and this calibration was particularly important for facilitating comparisons made between different systems or experiments. The proposed index of similarity was tested with data acquired from a recently completed study of contaminant removal from pulp mill wastewater. The results suggest that this index can be used as a screening tool to rapidly process microbial fatty acid (MFA) compositional data, with the objective of making preliminary identification of underlying trends in (MFA) community structure, over time or between experimental conditions. Copyright 2002 John Wiley & Sons, Ltd. [source]

New concepts of microbial treatment processes for the nitrogen removal in wastewater

Ingo Schmidt
Abstract Many countries strive to reduce the emissions of nitrogen compounds (ammonia, nitrate, NOx) to the surface waters and the atmosphere. Since mainstream domestic wastewater treatment systems are usually already overloaded with ammonia, a dedicated nitrogen removal from concentrated secondary or industrial wastewaters is often more cost-effective than the disposal of such wastes to domestic wastewater treatment. The cost-effectiveness of separate treatment has increased dramatically in the past few years, since several processes for the biological removal of ammonia from concentrated waste streams have become available. Here, we review those processes that make use of new concepts in microbiology: partial nitrification, nitrifier denitrification and anaerobic ammonia oxidation (the anammox process). These processes target the removal of ammonia from gases, and ammonium-bicarbonate from concentrated wastewaters (i.e. sludge liquor and landfill leachate). The review addresses the microbiology, its consequences for their application, the current status regarding application, and the future developments. [source]

Perturbation-independent community development in low-temperature anaerobic biological wastewater treatment bioreactors

Pdhraig Madden
Abstract The reproducibility and stability of low- temperature anaerobic wastewater treatment systems undergoing transient perturbations was investigated. Three identical anaerobic expanded granular sludge bed-based bioreactors were used to degrade a volatile fatty acid and glucose-based wastewater under sub-ambient (15C) conditions. The effect of a variety of environmental perturbations on bioreactor performance was assessed by chemical oxygen demand removal. Temporal microbial community development was monitored by denaturation gradient gel electrophoresis (DGGE) of 16S rRNA genes extracted from sludge granules. Methanogenic activity was monitored using specific methanogenic activity assays. Bioreactor performance and microbial population dynamics were each well replicated between both experimental bioreactors and the control bioreactor prior to, and after the implementation of most of the applied perturbations. Gene fingerprinting data indicated that Methanosaeta sp. were the persistent, keystone members of the archaeal community, and likely were pivotal for the physical stability and maintenance of the granular biofilms. Cluster analyses of DGGE data suggested that temporal shifts in microbial community structure were predominantly independent of the applied perturbations. Biotechnol. Bioeng. 2010;105: 79,87. 2009 Wiley Periodicals, Inc. [source]