Showing papers on "Wastewater published in 2008"

Brewery wastewater treatment using air-cathode microbial fuel cells.

Abstract: Effective wastewater treatment using microbial fuel cells (MFCs) will require a better understanding of how operational parameters and solution chemistry affect treatment efficiency, but few studies have examined power generation using actual wastewaters. The efficiency of wastewater treatment of a beer brewery wastewater was examined here in terms of maximum power densities, Coulombic efficiencies (CEs), and chemical oxygen demand (COD) removal as a function of temperature and wastewater strength. Decreasing the temperature from 30 degrees C to 20 degrees C reduced the maximum power density from 205 mW/m2 (5.1 W/m3, 0.76 A/m2; 30 degrees C) to 170 mW/m2 (20 degrees C). COD removals (R COD) and CEs decreased only slightly with temperature. The buffering capacity strongly affected reactor performance. The addition of a 50-mM phosphate buffer increased power output by 136% to 438 mW/m2, and 200 mM buffer increased power by 158% to 528 mW/m2. In the absence of salts (NaCl), maximum power output varied linearly with wastewater strength (84 to 2,240 mg COD/L) from 29 to 205 mW/m2. When NaCl was added to increase conductivity, power output followed a Monod-like relationship with wastewater strength. The maximum power (P max) increased in proportion to the solution conductivity, but the half-saturation constant was relatively unaffected and showed no correlation to solution conductivity. These results show that brewery wastewater can be effectively treated using MFCs, but that achievable power densities will depend on wastewater strength, solution conductivity, and buffering capacity.

Estimating community drug abuse by wastewater analysis.

Abstract: BackgroundThe social and medical problems of drug abuse are a matter of increasing global concern. To tackle drug abuse in changing scenarios, international drug agencies need fresh methods to moni...

Biological nitrogen removal with nitrification and denitrification via nitrite pathway

Abstract: The efficiency of wastewater treatment practices can be significantly improved through the introduction of new microbial treatment technologies. In order to meet increasing stringent discharge standards, new applications and control strategies for the sustainable removal of ammonium from wastewater have to be implemented. Partial nitrification to nitrite was reported to be technically feasible and economically favorable, especially when the wastewater with high ammonium concentrations or low C/N ratios was treated. For successful implementation of the technology, the critical point is how to maintain the partial nitrification of ammonium to nitrite. Nitritation can be obtained by selectively inhibiting the nitrite oxidizing bacteria through appropriate regulation of the system's DO concentration, microbial SRT, pH, temperature, substrate load, operational and aeration pattern, inhibitor and so on. This review addresses the microbiology, its consequences for application, the current status regarding application, and its future developments.

Removal of oxide nanoparticles in a model wastewater treatment plant: influence of agglomeration and surfactants on clearing efficiency.

Abstract: The rapidly increasing production of engineered nanoparticles has created a demand for particle removal from industrial and communal wastewater streams. Efficient removal is particularly important in view of increasing long-term persistence and evidence for considerable ecotoxicity of specific nanoparticles. The present work investigates the use of a model wastewater treatment plant for removal of oxide nanoparticles. While a majority of the nanoparticles could be captured through adhesion to clearing sludge, a significant fraction of the engineered nanoparticles escaped the wastewater plant's clearing system, and up to 6 wt % of the model compound cerium oxide was found in the exit stream of the model plant. Our study demonstrates a significant influence of surface charge and the addition of dispersion stabilizing surfactants as routinely used in the preparation of nanoparticle derived products. A detailed investigation on the agglomeration of oxide nanoparticles in wastewater streams revealed a high stabilization of the particles against clearance (adsorption on the bacteria from the sludge). This unexpected finding suggests a need to investigate nanoparticle clearance in more detail and demonstrates the complex interactions between dissolved species and the nanoparticles within the continuously changing environment of the clearing sludge.

Wastewater Treatment in Constructed Wetlands with Horizontal Sub-Surface Flow

Abstract: The Authors.- Preface.- Introduction.- Transformation Mechanisms Of Major Nutrients And Metals In Wetlands.- Wetland Plants.- Types Of Constructed Wetlands For Wastewater Treatment.- Horizontal Flow Constructed Wetlands. Types Of Wastewater Treated In HF Constructed Wetlands.- The Use Of HF Constructed Wetlands In The World.- References.-Suggested Reading.- Subject Index.

Handbook of Water and Wastewater Treatment Plant Operations

Abstract: Water and Wastewater Operations: An Overview Current Issues in Water and Wastewater Treatment Operations Water/Wastewater Operators Upgrading Security Water/Wastewater References, Models, and Terminology Water/Wastewater Operations: Math and Technical Aspects Water/Wastewater Math Operations Blueprint Reading Water Hydraulics Fundamentals of Electricity Hydraulic Machines: Pumps Water/Wastewater Conveyance Characteristics of Water Basic Water Chemistry Water Microbiology. Water Ecology Water Quality Biomonitoring, Monitoring, Sampling, and Testing Water and Water Treatment Potable Water Source Watershed Protection Water Treatment Operations Wastewater and Wastewater Treatment Wastewater Treatment Operations Appendix A. Answers to Chapter Review Questions Appendix B. Formulae Index

Application of Nanoparticles in Waste Water Treatment

Abstract: In the area of water purification, nanotechnology offers the possibility of an efficient removal of pollutants and germs. Today nanoparticles, nanomembrane and nanopowder used for detection and removal of chemical and biological substances include metals (e.g. Cadmium, copper, lead, mercury, nickel, zinc), nutrients (e.g. Phosphate, ammonia, nitrate and nitrite), cyanide, organics, algae (e.g. cyanobacterial toxins) viruses, bacteria, parasites and antibiotics. Basically four classes of nanoscale materials that are being evaluated as functional materials for water purification e.g. metal-containing nanoparticles, carbonaceous nanomaterials, zeolites and dendrimers. Carbon nanotubes and nanofibers also show some positive result. Nanomaterials reveal good result than other techniques used in water treatment because of its high surface area (surface/volume ratio). It is suggested that these may be used in future at large scale water purification. It is also found that the coliform bacteria treated with ultrasonic irradiation for short time period before Ag- nanoparticle treatment at low concentration, enhanced antibacterial effect. In future, combination of both may be the best option for treatment of waste water.

USE OF SELECTED ADVANCED OXIDATION PROCESSES (AOPs) FOR WASTEWATER TREATMENT - A MINI REVIEW

Abstract: Advanced oxidation processes (AOPs) are widely used for the removal of recalcitrant organic constituents from industrial and municipal wastewater. The aim of this study was to review the use of titanium dioxide/UV light process, hydrogen peroxide/UV light process and Fenton’s reactions in wastewater treatment. The main reactions and the operating parameters (initial concentration of the target compounds, amount of oxidation agents and catalysts, nature of the wastewater etc) affecting these processes are reported, while several recent applications to wastewater treatment are presented. The advantages and drawbacks of these methods are highlighted, while some of the future challenges (decrease of operational cost, adoption of strategies for processes integration) are discussed.

Electricity generation and treatment of paper recycling wastewater using a microbial fuel cell

Abstract: Increased interest in sustainable agriculture and bio-based industries requires that we find more energy-efficient methods for treating cellulose-containing wastewaters. We examined the effectiveness of simultaneous electricity production and treatment of a paper recycling plant wastewater using microbial fuel cells. Treatment efficiency was limited by wastewater conductivity. When a 50 mM phosphate buffer solution (PBS, 5.9 mS/cm) was added to the wastewater, power densities reached 501 ± 20 mW/m2, with a coulombic efficiency of 16 ± 2%. There was efficient removal of soluble organic matter, with 73 ± 1% removed based on soluble chemical oxygen demand (SCOD) and only slightly greater total removal (76 ± 4%) based on total COD (TCOD) over a 500-h batch cycle. Cellulose was nearly completely removed (96 ± 1%) during treatment. Further increasing the conductivity (100 mM PBS) increased power to 672 ± 27 mW/m2. In contrast, only 144 ± 7 mW/m2 was produced using an unamended wastewater (0.8 mS/cm) with TCOD, SCOD, and cellulose removals of 29 ± 1%, 51 ± 2%, and 16 ± 1% (350-h batch cycle). These results demonstrate limitations to treatment efficiencies with actual wastewaters caused by solution conductivity compared to laboratory experiments under more optimal conditions.

Factors affecting the removal of organic micropollutants from wastewater in conventional treatment plants (CTP) and membrane bioreactors (MBR)

Abstract: As a consequence of insufficient removal during treatment of wastewater released from industry and households, different classes of organic micropollutants are nowadays detected in surface and drinking water. Among these micropollutants, bioactive substances, e.g., endocrine disrupting compounds and pharmaceuticals, have been incriminated in negative effects on living organisms in aquatic biotope. Much research was done in the last years on the fate and removal of those compounds from wastewater. An important point it is to understand the role of applied treatment conditions (sludge retention time (SRT), biomass concentration, temperature, pH value, dominant class of micropollutants, etc.) for the efficiency of conventional treatment plants (CTP) and membrane bioreactors (MBR) concerning the removal of micropollutants such as pharmaceuticals, steroid- and xeno-estrogens. Nevertheless, the removal rates differ even from one compound to the other and are related to the physico-chemical characteristics of the xenobiotics.

Biological Removal of Nitrogen from Wastewater

Abstract: The removal of ammonia from wastewater has become a worldwide emerging concern because ammonia is toxic to aquatic species and causes eutrophication in natural water environments (Tchobanoglous et al. 2003). Nitrogen compounds in wastewater can only be effectively removed by biological approaches (EPA 1993; Zhu et al. 2007a,b). Based on the microbial nitrogen cycle and the metabolism of inorganic nitrogen compounds (Fig. 1), many biological technologies and processes have been developed and implemented for nitrogen removal from wastewater, such as predenitrification (Anoxic/Oxic), modified Bardenpho, Bio-denitro, sequencing batch reactor (SBR), oxidation ditch (OD), step feeding, anaerobic/anoxic/ aerobic (A2/O), and University of Cape Town (UCT) processes (Wentzel et al. 1992; Ostgaard et al. 1997; Williams and Beresford 1998; Tchobanoglous et al. 2003; Pai et al. 2004). These processes have been widely employed in wastewater treatment plants for nitrification and denitrification (EPA 1993). However, with the effluent discharge standards having become more stringent (<10mg total nitrogen/L), conventional processes cannot meet the new requirements (Khin and Annachhatre 2004).