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The article discusses several principles and practical considerations need to be known by operator of water resource recovery facilities about activated sludge. Topics discussed include knowledge and principles of mean cell residence time or solids residence time, building of mixed-liquor volatile suspended solids (MLSS) without biochemical oxygen demand (BOD) and role of return activated sludge rate (RAS) to controls the secondary clarifier.

The article presents a case study which demonstrates that the creative use of a secondary wastestream can successfully manage high and variable total dissolved solids (TDS) conditions. Topics include a polymer manufacturing facility which operated four sequencing batch reactors (SBRs) with pure oxygen aeration, use of contact stormwater at the facility for TDS control, and effluent biochemical oxygen demand at the facility after membrane bioreactor startup.

The article features the wastewater pretreatment facilities included in the overall plant design of White Plains, New York-based The Dannon Co. production facility that opened in West Jordan, Utah in 2000. The pretreatment facility enabled the plant to discharge wastewater acceptable to the City of West Jordan and South Valley Water Reclamation Facility. The facility was designed to remove biochemical oxygen demand and total suspended solids (TSS), and adjust wastewater pH prior to discharge.

The article narrates how teams around the world prepare for national competitions. The team Equipo KSB-Hydro represented the U.S. at the 6th Olimpiadas Sanitarias in Buenos Aires, Argentina. OCWA Jets and Terminal Velocity are among the teams that will be competing in the Operations Challenge during the WEFTEC 2012 of the Water Environment Federation in New Orleans, Louisiana. The article also identifies the Spring Flag in New Jersey as one of the most prominent U.S. regional events.

The article discusses the use of optical dissolved oxygen (DO) sensors to measure oxygen concentration in water. It examines the introduction of optical DO measurement to the water industry. It describes the benefits and limitations of optical DO measurement. It cites the use of optical DO measurement in environmental activities such as wastewater treatment, river monitoring and fish farming.

The article focuses on the new wastewater treatment approach in Onancock, Virginia. The undertaking was in compliance with the limit of technology effluent standards set by Virginia's Chesapeake Bay Program. The town's treatment plant needs to limit its effluent to no more than 4 milligrams per liter (mg/L) of total nitrogen and 0.3 mg/L of total phosphorus, as well as its effluent biochemical oxygen demand (BOD) and total suspended solids (TSS) to less than 3.33 mg/L. To meet these requirements, the plant is being rehabilitated.

The article reports on the efforts of the Fresno-Clovis Regional Wastewater Reclamation Facility (RWRF) in California to meet requirements for effluent total suspended solids (TSS) and biochemical oxygen demand (BOD). The plant used a low dissolved-oxygen (DO) concentration in aeration tanks. Though this practice increased hydraulic and organic loads, settleability and effluent quality have improved.

This article discusses how several U.S. and European plants are using backwash filtration (CBF) techniques as attached growth processes for the biological conversion of nitrogen and polishing units for phosphorus removal. The CBF process removes biochemical oxygen demand (BOD) and suspended solids through physical separation with sand and then biologically converts ammonia by nitrifying biomass present on the sand grains. Sand circulation is based on the airlift principle that forces a mixture of biomass, sand, and water upward through a central pipeline.

This article discusses a remediation pilot project for a wastewater treatment plant in Savannah, New York. The municipality decided to use microbial inoculator generators to remove a clogging biomat and alleviate filter ponding. This process similar to the fixed film activated sludge process improved nitrification and resulted in improved or maintained concentrations of carbonaceous biochemical oxygen demand, total suspended solids and total Kjeldahl nitrogen. The Town of Savannah saved considerable costs by choosing to bioremediate the sand filter rather than replacing it which solved the filter ponding problem.

The article presents a number of misconceptions by wastewater treatment operators with regards to nitrification. These include: the view that a certain mean cell residence time (MCRT) is required to nitrify; the concept that nitrification needs long detention times; the myth that biochemical oxygen demand (BOD) has to be reduced to 20 mg/L before nitrification can start; the view that nitrification is a difficult process; the idea that solids resulting from nitrification are light and settle more slowly than non-nitrifying solids; and the concept that BOD loadings must be strictly limited.

The article describes the use of coarse monomedia filtration which has been proven to be a cost-effective alternative for treating combined sewer overflow (CSO) and sanitary sewer overflow (SSO) streams at remote locations. The City of Geneva, New York, the New York State Energy Research and Development Authority and CRA Infrastructure and Engineering Inc. conducted a pilot study to determine whether coarse monomedia filtration can treat total suspended solids (TSS) and biochemical oxygen demand (BOD) in pre-treated wastewater during wet weather conditions. Overall, findings indicated that coarse monomedia filters decreased TSS and BOD concentrations to acceptable levels.

The article focuses on the study that examines the treatment of municipal wastewater with an anaerobic reactor technology called the static granular bed reactor in the U.S. The study aims to determine if the anaerobic reactor would remove carbonaceous biochemical oxygen demand (CBOD) and total suspended solids (TSS) to meet surface discharge requirement. Results of the research revealed that the static granular bed reactor removed enough CBOD and TSS to meet the surface water discharge standard. In addition, it also suggested that anaerobic reactors need high static granular reactors to attain high levels of treatment.

The article presents information on the use of chemically enhanced clarification process in the field of wastewater treatment. The process involves adding coagulants or flocculants to wastewater before it enters a gravity settling process to promote three processes, like coagulation, flocculation, and precipitation, that improve clarifier performance. Certain clarifier designs, like inclined-plate settlers, solids contact/sludge recirculation, and ballasted sedimentation, can further improve chemically enhanced clarification results. It is reported that chemicals can be used to enhance clarification in any gravity sedimentation system. Adding chemicals to the primary clarification process improves biochemical oxygen demand and total suspended solids removal while increasing allowable peak loading rates. Chemically enhanced primary clarification also reduces effluent phosphorus levels, but the metal-salt dose will need to be controlled to ensure that primary clarifier effluent contains enough phosphorus to meet the nutrient requirements of the downstream biological treatment process or else the sludge won't settle well.

The article presents information on the biological contact process which uses bioflocculation to treat wet weather flows in wastewater treatment plants. The process requires few modifications to be retrofitted to existing wastewater treatment facilities and unlike physical/chemical treatment processes, it can meet secondary treatment requirements for both total suspended solids and biochemical oxygen demand. The biological contact process is a high-rate treatment system in which mixed liquor or return activated sludge is directed from a mainstream activated sludge plant to a small contact chamber with a short hydraulic detention time. Wet weather flows are treated in the contact chamber and then sent to secondary clarifiers for final liquid-solids separation. The process relies on biological flocculation to remove particulates. During wet weather, peak flows typically are retained in the contact tank for only a short period. Because of this small hydraulic retention time, engineers need to understand how various operating parameters affect the kinetics of particulate constituent removal. INSET: Comparing Biological Contact Process and Ballastedߪ..

The article examines Ohio's City of Dayton Division of Wastewater Treatment which protects the water quality of the Great Miami River. The treatment plant reportedly uses two secondary processes in series, effluent filtration and post-aeration to produce excellent quality effluent. It is stated that the plant's 20 high-rate trickling filters remove mainly 5-day carbonaceous biochemical oxygen demand (CBOD) and suspended solids (SS) while 8 activated sludge tanks work to nitrify ammonia.

The article explains the use of management ratios to measure performance of wastewater treatment plants. Among the ratios that could be useful for utilities include the removal efficiency of mercury, removal efficiency of biochemical oxygen demand (BOD), plant design capacity per 1000 population and cost of chemicals per ton of BOD removed. The article concludes that by understanding data and ratios, utility managers can identify strengths and weaknesses at their wastewater treatment plants.

The article discusses the evaluation of launder-type and conventional wash press screenings at a German wastewater treatment plant. It describes how influent screens remove both biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Aside from screen type, some of the factors considered in assessing quality of screenings include sewer length, pumping, and industrial inflow. It also offers details about a new leaching method developed to enhance screening performance.

The article presents a study which determined the shelf life of a laboratory prepared glucose-glutamic acid (GGA) solution under normal laboratory conditions and observed the effect of holding time on average values and standard deviations. The 5-day biochemical oxygen demand (BOD) test is explained including the approach and procedure used. Findings showed that GCA solution was stable up to 28 days.

Two letters to the editor are presented in response the articles "Solids yield surprise" in the June 2011 issue and "Taking a big hit" in the July 2011 issue.

A quiz about biochemical oxygen demand is presented.

The article discusses upgrading of the wastewater treatment plant in Fruitland, Maryland to remove nutrients, decrease biochemical oxygen demand and increase capacity. According to the authors, a sequencing batch reactor utilizing activated sludge was selected to protect the Chesapeake Bay watershed from pollutants. The system was installed with jet aeration, a remote monitoring and control system and an Ultraviolet disinfection unit to improve effluent quality. Since the plant went online, it has exceeded design requirements and met the standards of the National Pollution Discharge Elimination system permit.

The article focuses on wastewater treatment plants. A typical wastewater treatment plant uses physical, biological, and chemical processes to achieve stringent permit limits. Information has been given regarding the fate of total suspended solids (TSS) through the treatment processes. Some TSS will be removed through preliminary treatment, but it is not typically measurable due to the avoidance of including large particles during sampling and analysis. A significant reduction in TSS will occur in primary treatment, but the amount depends upon the relative proportion of settleable to nonsettleable components. Since the activated sludge process converts carbonaceous biochemical oxygen demand to solids and also accumulates solids, there is a significant increase in TSS in the anaerobic, anoxic, and aerobic zones. The concentration of TSS in each zone depends upon the process mode, the recycle rates, and the point of recycle. These solids will settle and concentrate in the secondary clarifier. Most will be pumped back to the head of the secondary process as return activated sludge, but some will be removed as waste activated sludge to maintain the desired solids retention time in the activated sludge process.

This section presents information about a typical advanced wastewater treatment plant. The plant may be used to track the path of carbonaceous biochemical oxygen demand.

The article reports on the Operations Challenge competition scheduled to be held at the wastewater treatment industry convention WEFTEC.07 on October 16, 2007 at the San Diego Convention Center in California. The competition is to include a safety event, featuring a simulation of an unconscious person in a manhole, a laboratory event, featuring biochemical oxygen demand analysis, and a collection systems event, which is to include the removal and replacement of a section of in-service polyvinyl chloride piping.

The article presents a perspective on the capabilities of the Scavenger Decontamination Vessel from Water Management Technologies Inc. in increasing the dissolved oxygen level of Twin Lake in Florida. Test results showed that Scavenger had raised DO levels in Twin Lake above the 4.0 mg/L required by the Department of Natural Resource Protection (DNRP).

Presents a correction to the article "Track the Fate of Carbonaceous Biochemical Oxygen Demand" that was previously published in the October 1, 2005 issue of the periodical "Water Environment and Technology."

Discusses the use of solar-powered circulators to reduce energy costs and high biological oxygen demand in the U.S. Evaluation of various stationary and floating aerators based on short-circuiting concerns; Production of high water quality; Maintenance of solar array and circulator.

Johnstown, Colorado, needed a new water treatment system. Explosive population growth had exhausted the capabilities of its 1980s-era lagoon system, and it was not going to be able to meet the new permit limits, especially the ammonia limit, set to take effect in 2004. The city managers chose a Kaldnes North America's Moving Bed™ Biofilm Reactor (MBBR), which could meet the new nitrification limits much less expensively. Now, wastewater flows into the two pond cells for treatment of biochemical oxygen demand (BOD), and then enters the two-stage MBBR system, which removes remaining BOD and nitrifies all the ammonia.