Water Treatment Requirements Research Articles

Design of a high-temperature thermal ballast water treatment system

The introduction of non-indigenous marine species to foreign environments through the medium of ballast water has led to a research focus on the design of onboard ballast water treatment systems. Such systems must be capable of meeting new International Maritime Organization (IMO) standards while also having minimal effect on the environment and on the operational costs and safety of the vessel. Thermal treatment of ballast water appears to be a promising solution, although the application of low-temperature treatment methods may be limited by the time required for the process. A thermodynamic model is presented for a two-stage heat exchanger system to be used for high-temperature treatment of ballast water during discharge. The model may be used for estimation of ballast water treatment requirements during the design phase for a vessel. It was also used to size a pilot-scale, high-temperature treatment system that has been tested onboard ship with regard to the biological effectiveness of the treatment method.

English

In 2003, Red Chris Development Company started collecting baseline data to support its application for environmental approvals to mine the Red Chris porphyry copper-gold deposit located in northwestern British Columbia, Canada. An extensive geochemical testing program revealed that the majority of the waste rock has the potential to generate acid. However, the presence of significant quantities of carbonate minerals indicated that most of the rock would probably take several decades to generate acid. This precluded determination of which rock components would leach under acidic conditions using conventional laboratory methods. This information was required to predict future water chemistry and potential requirements for water treatment. As an alternative, waste-rock seepage chemistry data from six operating or recently closed porphyry mines in British Columbia were compiled and evaluated to investigate common hydrogeochemical features which could be used to predict water chemistry at Red Chris. The resulting database contains dissolved ion chemistry spanning the full range of pH conditions. The database indicated that dissolution of aluminum minerals such as biotite and chlorite exert a strong consistent pH control which can be explained by the solubility of basic aluminum sulfates and hydroxide. Likewise, iron concentrations were similar at all sites and appear to follow the solubility of ferric hydroxide. Dissolved concentrations of copper, zinc, cadmium, and molybdenum in waters were related to pH but reflected the variable presence of minerals such as chalcopyrite, sphalerite (zinc, cadmium) and molybdenite (molybdenum). In conclusion, concentrations of major ions affecting drainage acidity (sulfate, aluminum, and iron) are very similar at different sites, but concentrations of other elements depend on the abundance of their sulfide minerals. Additional Keywords: Acid rock drainage, prediction, metals.

Learning Sustainability by Design

Engineering education has focused on the mathematical and scientific principles which underpin proper design. Technological capabilities have, in some instances, overcome society's ability to adapt behavior to new technologies. Sustainable systems should be engineered to address economic, environmental, and behavioral issues as well as technical issues. Developing education curricula that encourages students to consider all facets involved in sustainable systems has challenged engineering programs. A pilot course based upon the design of a sanitation facility for a school in Azové, Benin, was taught in the 2004–2005 academic year. The objective of the course was to create a meaningful project that would teach sustainability as part of the design process. Over 1,200 7th- to 10th-grade students at CEG in Azové lack access to clean water and basic sanitation facilities. A site visit to the CEG confirmed that water and sanitation were priorities of the school board and parents of the children. Students at Gonzaga University designed a water and sanitation system for CEG and learned about sustainability requirements for structures, hydraulics, and water and wastewater treatment. Upon implementation of the proposed design, exposure to pathogenic organisms is expected to decrease substantially. Students were encouraged to consider sustainability issues in design and problems associated with water and sanitation in the developing world. Incorporating sustainability lessons through design and peer presentation significantly improved the education in global awareness and sustainability as perceived by students and professionals.

Ozonation of seawater from different locations: Formation and decay of total residual oxidant—implications for ballast water treatment

Ballast water is a likely cause for worldwide transfer of non-indigenous aquatic species because of the large volumes and frequency of possible inoculations. Ozone is one treatment option being considered for eliminating non-indigenous species in ballast water. When ozone is applied to seawater, secondary disinfectants are formed, commonly measured and expressed as total residual oxidant (TRO). The goal of this study was to determine those variables most likely to affect the rate of TRO increase during ozonation and the subsequent TRO decline that occurs over time. These parameters strongly influence the efficacy of ozone treatments aimed to eliminate organisms present in ballast water. Seawater was obtained from Puget Sound, Washington; Cape Fear, North Carolina; and San Francisco Bay. Results indicated that seawater characteristics, including the organic content and ammonia, affect the amount of ozone required to achieve a desired TRO level and rate of TRO decay, and therefore need to be considered in determining ozone requirements for ballast water treatment.

Influence of mine hydrogeology on mine water discharge chemistry

Abstract Using data for 81 coal mine discharges in the UK, the influence of discharge hydrogeology on discharge chemistry is assessed and typical chemical parameters derived for five discharge types. A combination of modified and new classification schemes is used to differentiate between the various discharge sources. Drainage from spoil tips generally has a pH below 5 and net-alkalinity values as low as — 2500 mg l −1 CaCO 3 . Drainage from flooded workings and pumped discharges are net-alkaline, while drainage from flooded and free draining workings are either moderately net-alkaline or net-acidic. Iron is the major contaminant of concern, although many mine waters contain less than 30 mg l −1 and Fe/SO 4 ratios are less than unity. The classification schemes developed can be used to assess mine water treatment requirements and processes operating in passive treatment systems.

Reduction of suspended solids following hydroclassification of metal-contaminated soils

Remediation of metals-contaminated soil typically uses solidification/stabilization and “dig and haul”. Soil washing and physical separation have been applied to a much lesser extent to reduce soil volumes requiring aggressive treatment and to improve performance of follow-up treatments. In earlier work [J. Hazard. Mater. 66 (1999) 15], we used a simple, vertical-column hydroclassifier, to separate four soils contaminated with heavy metals, defining a “best case” performance for larger-scale (minerals processing) equipment. Such processes, using water-based slurries, generate substantial volumes of water with suspended solids. These typically contain disproportionately high concentrations of heavy metals. Here, we performed an initial screening of settling, coagulation, and centrifugation for reducing suspended solids, and thus suspended metals from soil slurries following processing. The four soils, previously hydroclassified, were sieved to <600 μm, slurried with a 4:1 weight ratio of water, and allowed to settle. Slurry samples were collected at settling times of 0, 0.0833, 1, 5, and 22–24 h. Coagulant (alum) addition and centrifugation were investigated. The slurries were filtered, digested, and analyzed by atomic absorption for lead and chromium content. Two soil slurries clarified in <5 min. In all four cases, 90% of solids and metals settled within 5 h. However, completion may require up to 24 h, or other intervention, i.e. coagulants. The metal concentration in the residual suspended solids increased with settling time, implying an enrichment of metals in finer, suspended particles. Metals dissolved in the slurry water ranged from 3 to 5 mg/l for chromium and lead. This screening study provides guidance for water treatment requirements and treatability studies for the integration of hydroclassification and solids removal.

INFLUENCE OF LIMING AND TOPSOIL THICKNESS ON VEGETATIVE GROWTH AND LEACHATE QUALITY OF ACIDIC COAL REFUSE

Coal waste materials inhibit direct vegetation establishment due to adverse physical and chemical properties, particularly low water retention and high potential acidity. The Moss No. 1 coal refuse pile is located in Dickenson County, Virginia, and was idled in the late 1980`s with little topsoil resource available for final closure. The refuse was acidic (Total-S = 0.38%; pH = 3.6), black, high (70%) in coarse fragments, and had a low water holding capacity (4.5% in 6.0 over a two-year period, which resulted in greater vegetative cover and biomass than the control plots. All topsoil treatments resulted in greater vegetative cover and biomass than plots treated with lime only due to improved surface soil physical and chemical properties. A topsoil treatment of 60 cm gave the thickest vegetative cover and biomass yield. Such a treatment, however, would be cost-prohibitive at this location. Application of 27 Mg/ha of lime tomore » the refuse surface along with 15 cm of topsoil produced acceptable two-year vegetative cover and biomass, and appeared to be the optimal treatment for this particular situation. Both liming and topsoil had no affect on leachate pH and the electrical conductivity in leachates collected below the plots. This suggests that surface revegetation will have little effect on the quality of water draining through the pile, so long term water treatment requirements may not be reduced by successfully revegetating the pile surface.« less

Main Features of Large Water Treatment Plants in Japan

Japan, one of the most industrialized countries in the world, has water treatment processes that have some unique features. Similar in size and latitude to the state of California, Japan has a population of 120 million people heavily concentrated in large urban areas. Seasonal typhoons, as well as population density, affect the requirements of water treatment. This article summarizes a visit to six treatment plants in the Tokyo and Osaka regions.

Alcoholic Fermentation of beet molasses: study on stillage recycle

Stillage recycle in beet molasses alcoholic fermentation can be lower the production costs by a decrease of energy requirements for waste water treatment but it becomes necessary to optimise, separately, the sugar and non sugar contents of the wort. It is shown that the increase of the wort osmolality, linked to stillage recycle disturbs yeast metabolism above 1,5 osmol. The observed inhibition which is dependent on both sugar and non sugar concentrations leads to an apparent link between yeast behaviour and the dry matter percent of the worts.

Drinking Water Policy in the United States

The Safe Drinking Water Act of 1974 directed the U.S. Environmental Protection Agency (EPA) to develop regulations that limit the level of contaminants in public drinking waters. The 1986 amendments to the Safe Drinking Water Act further expands the agency's role in specifying numerical limits for physical, chemical, and biological parameters. The effect of changing water policies in the United States is illustrated by using the proposed Surface Water Treatment Requirements Rule (SWTRR) as an example. The SWTRR will affect every surface water system in the United States. Those systems which do not currently filter will need to satisfy an ongoing set of rigid requirements to avoid filtration. For systems that already filter their water, new degrees of disinfection and treatment are being proposed. Information is also presented regarding the assistance that research centers and foundations can provide for both developing and developed nations. In particular, the roles of the American Water Works Research Fo...

The use of reverse osmosis as a 35,600m 3/day concentrator in the waste water management scheme at 4640 MW Bayswater/Liddell Power Station complex - Australia

Water is an essential resource for power generation. It is used for steam generation, transportation, cooling, washdown, domestic services and in miscellaneous process water systems. The water distribution system and storages extend throughout a power station and interface with virtually all of the plant. The quality of water required for.each application varies from demineralised water with a conductivity of less than 10μS/m, used as boiler make-up, to brackish or saltwater used for ash transportation or cooling. The quality of water used for each application must be carefully controlled to ensure safety of personnel and prevent damage to equipment by scaling or corrosion while minimising water treatment cost. In recent years it has also become necessary to design power station water management systems to minimise water consumption as well as satisfy more stringent environmental requirements. This has resulted in a significant increase in water treatment requirements including water recycle and reuse via water recovery system. The Electricity Commission of New South Wales' (ECNSW) coal fired Bayswater/Liddell Power Station complex, which has a combined generating capacity of 4640 MW, includes one of the world's largest power station water treatment and water management systems. The water systems associated with both Bayswater and the adjacent Liddell Power Station will achieve “Zero Discharge” of all aqueous streams from the combined power station sites. To achieve “Zero Discharge” without deterioration of the water quality of the associated water storages, approximately 24,000 tonnes per year (66 tpd) of dissolved salts must be removed from the power stations water systems. The water treatment plant included in the water management scheme for Bayswater will have the capacity to remove 36,000 tpa (100 tpd) of dissolved salts from the power stations water systems. The capacity to remove additional salts will enable the Commission to improve the quality of water in the Liddell Power Station cooling dam (Lake Liddell) which has deteriorated since the commissioning of Liddell Power Station in 1971. The water treatment technologies that form part of the Bayswater/Liddell water management scheme include 160,000 m 3/day of lime softening, a 149,000 m 3/day carboxylic cation exchange resin alkalinity reduction system, a 35,600 m 3/day reverse osmosis (R.O.) facility incorporating extensive pretreatment, and a 6,600 m 3/day brine concentrator system (vapour compression evaporators operating with seed recycle). This paper presents an overview of the conceptual design of the Bayswater/Liddell Power Station water management system with focus on the detailed design and initial operation of the R.O. osmosis plants which have been installed as part of the cooling water sidestream treatment plant. The R.O. plants are installed to concentrate cooling tower blowdown at high recovery to minimise subsequent treatment of the R.O. reject using brine concentrators. The R.O. system is the world's largest installation of its type treating cooling tower blowdown with a designed salinity of 2500 mg/l operating at a design recovery rate of 82.5%. The paper will also discuss the impact of potential scalents (such as CaSO 4, BaSO 4, and CaF 2) on the operation of the R.O. concentrator at the high recovery rates. Results of pilot plant efforts to determine upper limits of concentration using R.O. will be presented along with recommendations of the role of R.O. in similar projects.

Management Guidelines for Small Water Supply Systems Part IV

Presented in this section are guidelines regarding various types of water rate schedules that govern customer charges, types of piping material, determination of water treatment requirements, and ways of financing a utility.

Water Treatments in Trickle Irrigation Systems

Water treatment requirements of Colorado River water for eight types of trickle emitters were being determined using six kinds of treatments, including screen and sand filtration, and combinations of hypochlorite and acid additions. With the water used, removal of suspended particulate materials by sand filtration maintained emitter performance over the 2-yr study, but sediment buildup had to be controlled for long-term maintenance by flushing the lines and treating with chemicals.

An integrated power process model for ethylene production

This study develops an economic model of a newly designed ethylene plant to evaluate the effects of increasingly restrictive waste water treatment requirements on the costs of producing ethylene, feedstock choice, and the marginal costs of treating major pollutants. Zero discharge of pollutants to the water is attained in the model plant at a production cost increase of 6.9%. Secondary treatment of organic pollutants increases production costs 0.79% with once‐through cooling and 5.15% with recycle cooling. The controlling organic pollutants at each treatment level are identified, and estimates are made of the potential savings in waste treatment from redesign of the production facilities to reduce the raw waste loads of each pollutant.

EXPANDING WASTE WATER TREATMENT CONSIDERATIONS AT CORPS OF ENGINEERS RECREATION AREAS1

ABSTRACT. There have been many changes in the waste water treatment requirements at St. Louis District Corps of Engineers projects over the past few years. Discussed are the methods considered for treating these wastes. Extended aeration plant, followed by filtration, is the process used in most of the areas. The treatment plant operators have become key members of the project operation team. A discussion of the Districts operator training program is presented along with the operator's job requirements. Through a Spring inspection of all treatment plants in the District, a mechanism has been provided for encouraging feedback to the design engineer from the operator.

Water Treatment for Once-Through Steam Generators

Water Treatment for Once-Through Steam Generators

Activated sludge Kinetics and Effluent Quality

Problem of residual soluble organics in effluents for accurate effluent quality prediction in order to permit economic balance between extended waste treatment and chemical requirements for water treatment; influence and interrelationships of treatment unit hydraulics and process kinetics; data for process design and method of experimental determination of design criteria.