It’s the call no water treatment plant superintendent wants to receive, especially not while on vacation. Andy McClure, Superintendent of Toledo, Ohio’s Collins Park Water Treatment Plant, answered his phone to hear his head of operations report that the level of microcystin in the finished water was high, caused by a large harmful algal bloom (HAB) that was impacting the plant’s Lake Erie intake.
An MABR is essentially a biological wastewater treatment process that utilizes seemingly passive aeration through oxygen-permeable membranes. Oxygen transfer through the MABR membranes is diffusion based: driven by concentration differences such that oxygen passes from air at atmospheric pressure into water at a higher hydrostatic pressure. This oxygen transfer mechanism, wherein air is supplied to the process at very low pressure, is the reason MABRs have significantly lower energy consumption compared to other wastewater treatment processes, such as conventional activated sludge (CAS), that utilize diffusers. This energy savings is one of the key reasons MABRs are gaining traction in the municipal wastewater industry.
Faced with rising operating costs due to increasing energy and chemical prices as well as stricter effluent permit limits, many operators and engineers are turning to sensors and automation as a means to enhance treatment performance and reduce operating costs while limited capital expenses. In order to overcome these challenges, an advanced process control solution was implemented in an aerobic digester in Green Lake, Wisconsin.
The city of Black River Falls in Wisconsin used chemical treatment with ferric chloride (FeCl3) to achieve their effluent total phosphorus (TP) permit of 1.0 mg/l. Historically, the chemical dosing rate was manually adjusted on a daily basis based on the measured effluent TP concentration. The plant was upgraded with an OSCAR process performance optimizer control system with phosphorus controller, which uses continuous measurement of orthophosphate. Read the full case study to learn more.
Wastewater treatment plants (WWTP) are facing many challenges. Permits on nitrogen and phosphorus in the effluent water are progressively becoming stricter in order to protect surface waters from eutrophication. At the same time, plants are required to reduce both energy and chemical consumption and are often challenged with limited time and staff. In total, they are required to do more with less. In order to meet these challenges, a plant with a Sequencing Batch Reactor (SBR) in Green Lake, Wisconsin was upgraded with an advanced process control system – the OSCAR process performance optimizer with NURO controller.
This paper helps to understand the efficacy of BakerCorp Electrocoagulation (EC) technology and treatment process in treating selenium-contaminated mine effluent. Two mine effluent samples were treated by Baker EC. Selenium constituent concentrations in both water samples were reduced significantly to below reporting qualification limits. Based on the results of the effluent samples, electrocoagulation is an effective treatment option for waste streams found to contain selenium.
When the Cobb County-Marietta Water Authority (CCMWA) anticipated the need to upgrade the Hugh A. Wyckoff water treatment plant, they turned to granular activated carbon (GAC) technology after vetting several alternatives. The plant, a wholesaler in a two-plant system, processes up to 72 million gallons per day and serves about 350,000 people. Comprising of Wyckoff and the James E. Quarles treatment plant, CCMWA is the second largest water provider in Georgia.
Along the Indian River Lagoon adjacent to Vero Beach, Florida, both residents and government officials were becoming increasingly concerned about excessive nutrient loads and pollution.
The AquaNereda® Aerobic Granular Sludge System (AGS) is an innovative biological wastewater treatment technology that provides advanced treatment using the unique features of aerobic granular biomass. This advanced nutrient removal process can reduce footprint up to 75% and energy up to 50% when compared to conventional activated sludge systems.
Facing new limits on acceptable levels of DBPs in the drinking water, as well as age-old complaints about the taste of the water during the summer algal bloom, the North Texas Municipal Water District turned to ozone disinfection as a possible alternative able to address both concerns.
To protect the sensitive waters of the Neuse River Basin, the State of North Carolina formally adopted a nutrient management strategy in 1997 which established Total Maximum Daily Loads for all point source contributors of Total Nitrogen (TN) to the Neuse River. By upgrading its oxidation ditches, this Eastern NC plant saw a reduction of 76% TN compared to its average discharge from the past 6 years.
The state of Minnesota instituted a new water quality requirement that limits cities along the Minnesota River to a 1 mg/L Total Phosphorus limit by 2015 to prevent algae blooms and resulting pollution problems.
About Nutrient Removal
Nutrient removal from wastewater consists of treating wastewater to remove nitrogen and phosphorus before it reenters natural waterways. High levels of nitrogen and phosphorus in wastewater cause eutrophication, a process where excess nutrients stimulate excessive plant growth such as algal blooms and cyanobacteria. The decomposition of the algae by bacteria uses up the oxygen in the water causing other organisms to die. This creates more organic matter for the bacteria to decompose. In addition, some algal blooms can produce toxins that contaminate drinking water supplies.
As authorized by the Clean Water Act, the National Pollutant Discharge Elimination System (NPDES) permit program regulates point sources, such as municipal wastewater treatment plants, that discharge pollutants as effluent into the waters of the United States. In recent years, many of the States’ environmental bodies have lowered nutrient limits to arrest eutrophication. Maryland’s effort to protect the Chesapeake Bay and its tidal tributaries is perhaps the most notable example of nutrient removal in the US. Nutrient removal continues to be a growing area of focus for wastewater treatment throughout the world.
The removal of nitrogen and phosphorus require different nutrient removal processes. To remove nitrogen, the nitrogen is oxidized from ammonia to become nitrate through a process called nitrification. This process is then followed by denitrification where the nitrate is reduced to nitrogen gas which is released to the atmosphere and removed from the wastewater.
Nitrification is a two-step aerobic process which typically takes place in aeration tanks. Denitrification requires anoxic conditions to encourage the appropriate biological conditions to form. The activated sludge process is often used to reduce nitrate to nitrogen gas in anoxic or denitrification tanks.
Phosphorus can be removed biologically using polyphosphate accumulating organisms (PAOs) which accumulate large quantities of phosphorus within their cells and separate it from treated water. Phosphorus removal can also be achieved by chemical removal. Once removed as sludge, phosphorus may be stored in a land fill. However, many municipalities and treatment facilities are looking to resell the biosolids for use in fertilizer.