Aeration system improves mixing, oxygenation, & maintenance
When its brush rotor system failed, the city of Franklin, LA, dccidcd to replace it with an Airc-02 Triton aeration/mixer system, which about equaled the ongoing costs of refurbishing die rotors. The aerators met all the city's needs and a year later, city officials purchased more of the aerators for its second ditch.
Back in 2000, Franklin's wastewater treatment plant consisted of an activated sludge system in two parallel concrete oxi- dation ovals that relied on brush rotors for aeration. Two brush rotors were used in each ditch. The plant receives a total flow of 2.4 mgd that splits between the two ovals for treatment. Boat clarificrs are located in each oxidation oval. The size of each ditch is 688 ft x 23 ft x 11 ft.
The city's discharge limits are very strict. BOD and TSS effluent values must be less than 15 mg/1 and 23 mg/1 (daily maxi- mum), respectively. Aeration treatment per- formance and dependability is important to achieve these objectives.
The rotors had ongoing maintenance problems, according to John Ford, plant operator at the Franklin facility.
'We had so much trouble with the bear- ings. We had to go out and grease them every day and even on Saturdays. And, that was even following the advice of the manu- facturers' recommendation,' he said.
Eventually, the equipment started failing. 'The rotor broke in the middle, we lost a lot of manpower hours, and maintenance became very difficult and kind of danger- ous,' Ford said.
The decision was made to replace the failed rotor system with a new aeration system in earl)' 2000. John C. Fore, Jr., P.E., of Miller Engineers & Associates, located in Franklin, was die project manager.
A Site-Specific Tool for Optimizing Final Clarifier Design and Operation
The final clarifier is one of the most important unit processes and often determines the capacity of a treatment plant. Clarification is a solids separation process, which results in the removal of 99 percent or more of the suspended solids (biological floc) received from the activated sludge system. The separated solids are transported to the bottom of the clarifier and removed as return activated sludge (RAS). The clarifier failure can lead to solids carryover resulting in a reduction in solids retention time...
Fungal Based Treatment for Nitrogen and Phosphorus Decrease in Wastewater
Biological nutrient removal (BNR) technology can suffer poor performance or complete failure due to the fastidious nature of the bacteria used in the system. The bacteria involved necessitate strict operating conditions, multiple zones with one or more recycling lines, carbon source augmentation, and efficient aeration. For wastewater treatment plants receiving significant combined sewer overflows and industrial wastewater, maintaining a stable BNR system can becostly and challenging.Shoun et al (1991) demonstrated...
Aerators Enhance Aerobic Digestion Process
The city of Eden,N.C.,operates an extended aeration process designed for an average flow rate of 13.5 mgd with a mixed liquor suspended solids concentration that typically checks in about 6,000 mg/l. This high biomass concentration is necessary to provide a well-settling sludge and good effluent quality. Further, the plant influent is approximately 40% domestic wastewater and 60% industrial wastewater. The industrial component is dominated by textile facilities.The Eden Wastewater Treatment Plant (WWTP) generates...
Recovery of Precious Metal Catalysts - A New Process Using Supercritical Water Oxidation
Up to now, the recovery of precious metals used as catalysts in chemical processes has involved the use of incineration. Now, however, a British-Swedish joint venture has developed a process which uses supercritical water oxidation instead, which provides many economic and environmental advantages. Precious metals are used extensively in catalysts in a wide range of industrial chemical processes. Sometimes they are used in a homogeneous form, but more often fixed to a solid support for ease of handling. In many...
Sludge Disposal that’s Sustainable, Safe and Economically Viable
The Kemwater Recycling Process – KREPRO for treatment of sewage sludge is based on a completely new separation technology, which uses existing knowledge in an innovative way. It reduces both the organic and inorganic content of the sludge. The organic content is re-duced by about 30% and the inorganic about 70% if digested sludge is treated. All metals and salts are dissolved; the remaining undissolved inorganics are mainly silicates like sand and grit. In constast, most sludge treatment technologies used today...
The value of anaerobic purification for pulp and paper mill effluents
In comparison to the food industry, anaerobic treatment had a later and a slower start in the pulp & paper industry. The first plants were installed in the beginning of the eighties and at the moment the number of projects that has been counted is approximately 140. Many of these plants have been installed as a pre-treatment stage before an activated sludge plant and reduce at least 80% of the energy consumption and the waste activated sludge yield. In return the produced biogas gives a positive...
Performance of Floating Horizontal Aerators in Aerated Lagoons and Oxidation Ditches
INTRODUCTION When selecting aeration equipment to use for a specific application, issues to address include reliability, serviceability, capital cost, system appurtenances, and cost of operation and maintenance. Another important consideration is oxygen transfer rate (OTR). Horizontal floating aerators have relatively high transfer rates and have been used successfully in aerated lagoons and oxidation ditches. Using equipment with high OTR values reduces the horsepower input that is required and subsequently...
Japanese Organics Recycling Association Formed
Another backyard composting adage states that compost should have the feel of a wrung-out sponge — damp but not dripping wet. Actually, a wrung-out sponge may be on the dry side for composting, but the analogy does provide a great image for understanding the reasons for balancing moisture. Like a compost pile (or windrow or material in a vessel), a sponge is a solid mass containing an enormous network of pores. The pore spaces hold moisture, air and other gases. The wrung-out sponge has a good deal of water in...
Fires at Composting Facilities: Causes and Conditions
The subject of fires at composting facilities is a bad news/good news situation. The bad news is that fires are more common than we realize. Ask a group of facility operators if they have had to deal with a fire, and the majority will quietly admit they have. The good news is that we don’t realize that fires are fairly common at composting facilities. Most are neither frequent nor destructive enough to attract attention beyond the facility gates, with notable exceptions. Generally, operators are recognizing and...
Troubleshooting the Compost Pile
While composting is a biological process, we as composters must provide the microorganisms that do the work with the conditions they need to do their job. If there is a problem with the system, then look at it from the point of view of the microbe. What does that microbe need to function, and why isn’t it functioning correctly? Microorganisms need a source of energy organic feedstocks to feed on and draw energy. Some of that released energy causes the compost pile to heat. Besides energy, organisms need nutrients...
Composting Key to Meeting Landfill Organics Ban
The Halifax Regional Municipality (HRM) in Nova Scotia took a giant leap in 1998 to reaching a 50 percent diversion goal by 2000. Between July and November, 1998, organics collection carts were distributed to almost 100,000 households in the region. In December, two new composting facilities designed to process those materials, as well as feedstocks from the commercial sector, opened their doors. “The Halifax Regional Municipality’s new integrated solid waste-resource management system is ‘leading edge’ in all...
Bioremediation of an Oil Spill
Bioremediation is the method of choice to effectively clean up a small spill of hydrocarbons. In this case, five-hundred liters of BTEX has spilled from an above ground storage tank into a pasture that is located at the west edge of the Royal Roads University (RRU) grounds. The soil is classified as a Gleyed Eutric Brunisol based on recent laboratory analysis; it contains clay, but is fairly loose and porous for the upper meter, and then reaches an impermeable clay boundary (Burke, 1998). The dominant vegetation...
Bioremediation of Effluent the Pulp and Paper Industry
The treatment of industrial effluent from the paper manufacturing facilities in British Columbia is a major concern because the effluent is discharged into prime salmon habitat in the marine environment (Cross, 1994). High levels of biological oxygen demand (BOD) in the effluent reduce the dissolved oxygen (DO) available to species in the marine environment. In 1988, the Federal Department of Fisheries and Oceans reviewed the levels of DO and total suspended solids (TSS) that are discharged in the effluent...
Environmental Situation in Africa
Abstract Africa The economic and social needs of Africa depends more on its environmental resources but these natural resources are seriously declining and that is really effecting the entire region. Sustainable development in this rapidly changing region has become an imperative, and must take place in the complex context of a diverse and changing ecosystem, political transition and evolution toward market economies. The region is heading towards integrating environmental components into sectors like...
MSW Composting in the United States
Massachusetts became home to two new composting facilities that process MSW and biosolids. Nationally, the total number of operating plants is 19. Since the mid-1980s, BioCycle has been conducting an annual, nationwide survey of municipal solid waste (MSW) composting facilities. From the late 1980s into the early 1990s, when it was projected that landfill capacity would drop and tipping fees would skyrocket, interest in MSW composting was high. About two dozen companies were marketing systems and equipment, and...
Advanced Treatment of Textile Wastewater and its Cost by H2O2/UV Oxidation Process
Abstract Different parameters were investigated to evaluate their effect on the process removal efficiency of COD and color, including H2O2 concentration, UV power, multi-step addition of H2O2, and air bubbling. As a result, the color can be removed completely within 20 minutes, and the COD removal of approximately 90% can be achieved within 40 minutes of UV illumination. This process favors the H2O2 addition in one step rather than in four steps. Supply of oxygen does not enhance the process removal efficiency....
Breweries Industry - Pollution Prevention Guidelines
Introduction Pollution Prevention Guidelines to provide technical advice and guidance to staff and consultants involved in pollution-related projects. The guidelines represent state-of-the-art thinking on how to reduce pollution emissions from the production process. In many cases, the guidelines provide numerical targets for reducing pollution, as well as maximum emissions levels that are normally achievable through a combination of cleaner production and end-of-pipe treatment. The guidelines are designed to...
In Situ Physical/Chemical Treatment for Ground Water and Leachate
The main advantage of in situ treatments is that they allow ground water to be treated without being brought to the surface, resulting in significant cost savings. In situ processes, however, generally require longer time periods, and there is less certainty about the uniformity of treatment because of the variability in aquifer characteristics and because the efficacy of the process is more difficult to verify. Physical/chemical treatment uses the physical properties of the contaminants or the contaminated...
Introduction Land Treatment is a full-scale bioremediation technology in which contaminated soils, sediments, or sludges are turned over (i.e., tilled) and allowed to interact with the soil and climate at the site. The waste, soil, climate, and biological activity interact dynamically as a system to degrade, transform, and immobilize waste constitutes. Wastes are periodically tilled to aerate the waste. Soil conditions are often controlled to optimize the rate of contaminant degradation. Conditions normally...
Introduction The utilization of fungal biodegradation involves the controlled usage of these specially cultivated fungi to treat contaminants. White Rot Fungus White rot fungus has been reported to degrade a wide variety of organopollutants because of its lignin-degrading or wood-rotting enzymes. Two different treatment configurations have been tested for white rot fungus, in situ and bioreactor. An aerobic system using moisturized air on wood chips is used in a reactor for biodegradation. A reactor was used...
Common Treatment Train for Halogenated VOCs
In general, no single technology can remediate an entire site. Several treatment technologies are usually combined at a single site to form what is known as a treatment train. A system diagram of a common treatment train for halogenated VOCs is illustrated below. A ground water pumping system is used to pull contaminated water from the subsurface. The VOC contaminated water is pumped to a liquid phase granulated activated carbon (GAC) adsorption system. The GAC system removes VOCs in the water and the effluent is...
Management of Hazardous Wastes
` Management of hazardous waste is a growing concern in many countries. The long-term impacts and costs of improper disposal can be very high and the emphasis must be on prevention. A comprehensive management system should include (i) policies, institutions and effective regulations and (ii) adequate and acceptable disposal facilities (either public or private). This note outlines the key elements of such a system.` Problems Improper disposal of hazardous waste is an increasing problem in many developing...
Two Case Histories of Industrial Water Reuse Via Membrane Technology
Abstract This paper describes two successful applications of ultrafiltration (UF) and reverse osmosis (RO) membrane technology used to reclaim water, reduce waste water discharge costs. The first case history covers oily waste water treatment at a major aluminum beverage can manufacturing plant. The second case describes treatment of waste water from a multi-plating bath section of a major wheelchair manufacturing facility. The mechanisms of separation effected by both UF and RO are described at the molecular...