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The state of California has passed legislation to divert organic materials from landfills to reduce the emission of methane to the atmosphere. A large amount of this source separated organic (SSO) material is expected to be used as a feedstock for anaerobic digestion processes. Based on a review of properties for likely SSO feedstocks, it is clear that while SSO are high in volatile solids, they are also concentrated sources of nutrients (principally, ammonium). When SSO feedstocks are digested, these nutrients are released into the digestate, where ammonium can cause problems both within the digester and in downstream treatment processes. The focus of this paper is on the performance of two pilot studies designed to remove ammonia from a digester effluent. The process used in the study is a thermal stripping column with tray configuration, operating under a vacuum. In the first study, food waste digestate was treated as a slurry in the stripping column with and without NaOH addition. At process temperatures near 90 °C, the performance with and without caustic was similar. In the second study, centrate from a co-digestion facility, that blends food processing waste with wastewater process solids, was treated in the same thermal stripping column under the same conditions and without chemical addition. The results from both studies, which can be described using the same performance curves, are presented and discussed in this paper.
Harold Leverenz; Russel Adams; Jessica Hazard; George Tchobanoglous. Continuous Thermal Stripping Process for Ammonium Removal from Digestate and Centrate. Sustainability 2021, 13, 2185 .
AMA StyleHarold Leverenz, Russel Adams, Jessica Hazard, George Tchobanoglous. Continuous Thermal Stripping Process for Ammonium Removal from Digestate and Centrate. Sustainability. 2021; 13 (4):2185.
Chicago/Turabian StyleHarold Leverenz; Russel Adams; Jessica Hazard; George Tchobanoglous. 2021. "Continuous Thermal Stripping Process for Ammonium Removal from Digestate and Centrate." Sustainability 13, no. 4: 2185.
Population growth, the impacts of climate change, and the need for greater water security have made the reuse of wastewater, including potable use, increasingly desirable. As interest in potable reuse of wastewater increases, a variety of processes have been proposed for advanced water treatment following conventional wastewater treatment. In all cases, the operation and performance of advanced water treatment facilities (AWTFs) is improved when the treated wastewater feed is of the highest quality that can be achieved and the advanced water treatment (AWT) processes are operated at a constant flow. One proven method of optimizing the performance of wastewater treatment facilities (WWTFs) is constant flow operation with no extraneous return flows other than internal process recycle flows, such as return settled solids. A number of approaches can be used to achieve constant flow including flow equalization, divided treatment trains, and satellite treatment. The ways in which constant flow wastewater treatment benefits both WWTFs as well as the AWTFs are considered with special emphasis on the ability to achieve predictable log removal credits (LRCs) for specific microorganisms. Actual performance data from constant flow WWTFs are used to illustrate how LRCs are determined. Practitioner points Constant flow WWTFs should be considered to produce the highest quality secondary effluent for AWT. Flow equalization, divided treatment trains, and satellite treatment can be used to achieve constant flow to optimize wastewater treatment in small and medium size WWTFs. Flow equalization can be used to maximize the amount of wastewater that can be recovered for potable reuse. Important benefits of constant flow for wastewater treatment facilities include economic and operational savings, stable and predictable treatment performance, energy savings, ability to optimize performance for the removal of specific constituents, and the ability to assign pathogen log removal credits (LRCs). Important benefits of constant flow and optimized WWT for AWTFs include economic and operational savings; less pretreatment needed, including energy and chemical usage; elimination of the need to cycle treatment processes; and added factor of safety with respect to the required pathogen LRCs. In large WWTFs, constant flow for AWTFs will typically be achieved by effluent diversion; depending on the effluent quality additional pretreatment may be needed. The design and implementation of WWTFs and AWTFs for potable reuse should be integrated for optimal performance and protection of public health.
George Tchobanoglous; John Kenny; Harold Leverenz. Rationale for constant flow to optimize wastewater treatment and advanced water treatment performance for potable reuse applications. Water Environment Research 2021, 93, 1231 -1242.
AMA StyleGeorge Tchobanoglous, John Kenny, Harold Leverenz. Rationale for constant flow to optimize wastewater treatment and advanced water treatment performance for potable reuse applications. Water Environment Research. 2021; 93 (8):1231-1242.
Chicago/Turabian StyleGeorge Tchobanoglous; John Kenny; Harold Leverenz. 2021. "Rationale for constant flow to optimize wastewater treatment and advanced water treatment performance for potable reuse applications." Water Environment Research 93, no. 8: 1231-1242.
Crete, located in the South Mediterranean Sea, is characterized by long coastal areas, varied terrain relief and geology, and great spatial and inter-annual variations in precipitation. Under average meteorological conditions, the island is water-sufficient (969 mm precipitation; theoretical water potential 3284 hm3; and total water use 610 hm3). Agriculture is by far the greatest user of water (78% of total water use), followed by domestic use (21%). Despite the high average water availability, water scarcity events commonly occur, particularly in the eastern-south part of the island, driven by local climatic conditions and seasonal or geographical mismatches between water availability and demand. Other critical issues in water management include the over-exploitation of groundwater, accounting for 93% of the water used in agriculture; low water use efficiencies in the farms; limited use of non-conventional water sources (effluent reuse); lack of modern frameworks of control and monitoring; and inadequate cooperation among stakeholders. These deficiencies impact adversely water use efficiency, deteriorate quality of water resources, increase competition for water and water pricing, and impair agriculture and environment. Moreover, the water-limited areas may display low adaptation potential to climate variability and face increased risks for the human-managed and natural ecosystems. The development of appropriate water governance frameworks that promote the development of integrated water management plans and allow concurrently flexibility to account for local differentiations in social-economic favors is urgently needed to achieve efficient water management and to improve the adaptation to the changing climatic conditions. Specific corrective actions may include use of alternative water sources (e.g., treated effluent and brackish water), implementation of efficient water use practices, re-formation of pricing policy, efficient control and monitoring, and investment in research and innovation to support the above actions. It is necessary to strengthen the links across stakeholders (e.g., farmers, enterprises, corporations, institutes, universities, agencies, and public authorities), along with an effective and updated governance framework to address the critical issues in water management, facilitate knowledge transfer, and promote the efficient use of non-conventional water resources.
V. A. Tzanakakis; A. N. Angelakis; N. V. Paranychianakis; Y. G. Dialynas; G. Tchobanoglous. Challenges and Opportunities for Sustainable Management of Water Resources in the Island of Crete, Greece. Water 2020, 12, 1538 .
AMA StyleV. A. Tzanakakis, A. N. Angelakis, N. V. Paranychianakis, Y. G. Dialynas, G. Tchobanoglous. Challenges and Opportunities for Sustainable Management of Water Resources in the Island of Crete, Greece. Water. 2020; 12 (6):1538.
Chicago/Turabian StyleV. A. Tzanakakis; A. N. Angelakis; N. V. Paranychianakis; Y. G. Dialynas; G. Tchobanoglous. 2020. "Challenges and Opportunities for Sustainable Management of Water Resources in the Island of Crete, Greece." Water 12, no. 6: 1538.
Over the past 20 years, various new filter technologies have been developed that can be used to (1) enhance the performance of or (2) replace conventional primary treatment facilities. To enhance the performance of a primary sedimentation facility, primary effluent is filtered to further reduce the constituent concentrations discharged to the secondary treatment facilities. This form of primary enhancement is known as primary effluent filtration (PEF). In the second case, where some type of filter technology is used to replace primary sedimentation, the process application is known as primary filtration (PF). The principal focus of this paper is on the performance of the first full‐scale PF project using a fine pore cloth disc filter to maximize the diversion of carbon for the production of energy and to reduce energy usage. Performance data from related pilot‐scale cloth disc primary filter (CDPF) systems are included for process verification. The removal performance for total suspended solids (TSS) from the three CDPF installations varied from 83 to 85%, as compared to 55 to 60% typically achieved with primary sedimentation. The total overall TSS removal performance achieved with PF is essentially the same as that achieved with PEF, without the need for a primary sedimentation tank. The removal performance for five‐day biochemical oxygen demand (BOD5) from the three CDPF installations varied from 46 to 58%, as compared to 32 to 38% BOD removal typically achieved with primary sedimentation. The full‐scale CDPF results reported in this paper are from an on‐going research and demonstration project, conducted for the California Energy Commission (CEC), to demonstrate the potential energy savings that can be achieved through the implementation of PF.
Onder T. Caliskaner; George Tchobanoglous; Lilly Imani; Brian G. Davis. Performance evaluation of first full‐scale primary filtration using a fine pore cloth media disk filter. Water Environment Research 2020, 93, 94 -111.
AMA StyleOnder T. Caliskaner, George Tchobanoglous, Lilly Imani, Brian G. Davis. Performance evaluation of first full‐scale primary filtration using a fine pore cloth media disk filter. Water Environment Research. 2020; 93 (1):94-111.
Chicago/Turabian StyleOnder T. Caliskaner; George Tchobanoglous; Lilly Imani; Brian G. Davis. 2020. "Performance evaluation of first full‐scale primary filtration using a fine pore cloth media disk filter." Water Environment Research 93, no. 1: 94-111.
Prehistoric Hellenic civilizations like many other civilizations believed in gods and thought they had influence on the everyday life of the people. During the Bronze Ages the explanations of illness and health problems were based on mythological, divine, or religious (i.e., theocratic) reasoning or explanations. However, during the Classical and the Hellenistic periods, the Greeks clearly differentiated their thinking from all other civilizations by inventing philosophy and empirical science. Drains/sewers, baths and toilets and other sanitary installations reflect the high cultural and technological level of the period; they are also associated with hygienic and medical studies and practical applications. At that time, medicine was mainly based on clinical observations and scientific investigations. Prior to that time, in the Bronze Age, medicine was entirely confined to religious rituals and beliefs. In ancient Greece, medicine was practiced in Asclepieia (or Asklepieia), which were healing sanctuaries which also functioned as medical schools and hospitals. In the Classical Greece period, more than 400 Asclepieia were operating offering their medical services. The basic elements of each Asclepieia included a clean source of water and related infrastructure. At that time Hippocrates, the father of medicine, and his successors wrote a large number of medical texts in which the crucial role of water and sanitation is documented. They also identified numerous medical terms, many of which remain in use today. The Hippocratic treatises also contributed to the scientific evolution which occurred in later centuries, because they sought to explain the causes of observed natural phenomena in a deterministic way rather than on theocratic explanations in use at the time. In this paper, the evolution of hygiene, focusing on water use in ancient Greece is examined.
Andreas N. Angelakis; Georgios P. Antoniou; Christos Yapijakis; George Tchobanoglous. History of Hygiene Focusing on the Crucial Role of Water in the Hellenic Asclepieia (i.e., Ancient Hospitals). Water 2020, 12, 754 .
AMA StyleAndreas N. Angelakis, Georgios P. Antoniou, Christos Yapijakis, George Tchobanoglous. History of Hygiene Focusing on the Crucial Role of Water in the Hellenic Asclepieia (i.e., Ancient Hospitals). Water. 2020; 12 (3):754.
Chicago/Turabian StyleAndreas N. Angelakis; Georgios P. Antoniou; Christos Yapijakis; George Tchobanoglous. 2020. "History of Hygiene Focusing on the Crucial Role of Water in the Hellenic Asclepieia (i.e., Ancient Hospitals)." Water 12, no. 3: 754.
Comprehensive Source Control for Potable Reuse
George Tchobanoglous; Harold Leverenz. Comprehensive Source Control for Potable Reuse. Frontiers in Environmental Science 2019, 7, 1 .
AMA StyleGeorge Tchobanoglous, Harold Leverenz. Comprehensive Source Control for Potable Reuse. Frontiers in Environmental Science. 2019; 7 ():1.
Chicago/Turabian StyleGeorge Tchobanoglous; Harold Leverenz. 2019. "Comprehensive Source Control for Potable Reuse." Frontiers in Environmental Science 7, no. : 1.
George Tchobanoglous. Integrated wastewater management: The future of water reuse in large metropolitan areas. Integrated Environmental Assessment and Management 2018, 15, 160 -163.
AMA StyleGeorge Tchobanoglous. Integrated wastewater management: The future of water reuse in large metropolitan areas. Integrated Environmental Assessment and Management. 2018; 15 (1):160-163.
Chicago/Turabian StyleGeorge Tchobanoglous. 2018. "Integrated wastewater management: The future of water reuse in large metropolitan areas." Integrated Environmental Assessment and Management 15, no. 1: 160-163.
Denitrifying membrane bioreactors (MBRs) are being found useful in water reuse treatment systems, including net-zero water (nearly closed-loop), non-reverse osmosis-based, direct potable reuse (DPR) systems. In such systems nitrogen may need to be controlled in the MBR to meet the nitrate drinking water standard in the finished water. To achieve efficient nitrification and denitrification, the addition of alkalinity and external carbon may be required, and control of the carbon feed rate is then important. In this work, an onsite, two-chamber aerobic nitrifying/denitrifying MBR, representing one unit process of a net-zero water, non-reverse osmosis-based DPR system, was modeled as a basis for control of the MBR internal recycling rate, aeration rate, and external carbon feed rate. Specifically, a modification of the activated sludge model ASM2dSMP was modified further to represent the rate of recycling between separate aerobic and anoxic chambers, rates of carbon and alkalinity feed, and variable aeration schedule, and was demonstrated versus field data. The optimal aeration pattern for the modeled reactor configuration and influent matrix was found to be 30 min of aeration in a 2 h cycle (104 m3 air/d per 1 m3/d average influent), to ultimately meet the nitrate drinking water standard. Optimal recycling ratios (inter-chamber flow to average daily flow) were found to be 1.5 and 3 during rest and mixing periods, respectively. The model can be used to optimize aeration pattern and recycling ratio in such MBRs, with slight modifications to reflect reactor configuration, influent matrix, and target nitrogen species concentrations, though some recalibration may be required.
Mahamalage Kusumitha Perera; James D. Englehardt; George Tchobanoglous; Reza Shamskhorzani. Control of nitrification/denitrification in an onsite two-chamber intermittently aerated membrane bioreactor with alkalinity and carbon addition: Model and experiment. Water Research 2017, 115, 94 -110.
AMA StyleMahamalage Kusumitha Perera, James D. Englehardt, George Tchobanoglous, Reza Shamskhorzani. Control of nitrification/denitrification in an onsite two-chamber intermittently aerated membrane bioreactor with alkalinity and carbon addition: Model and experiment. Water Research. 2017; 115 ():94-110.
Chicago/Turabian StyleMahamalage Kusumitha Perera; James D. Englehardt; George Tchobanoglous; Reza Shamskhorzani. 2017. "Control of nitrification/denitrification in an onsite two-chamber intermittently aerated membrane bioreactor with alkalinity and carbon addition: Model and experiment." Water Research 115, no. : 94-110.
Iran is facing with a serious water crisis, which must be addressed if Iran is to move forward in becoming a developed nation. Iran’s water shortage problem has been caused by multiple factors including limited surface and groundwater availability. The current water shortage in Iran is an issue that can only be resolved by considering the entire water portfolio. One alternative solution to the water shortage problem in Iran is to adapt an integrated sustainable water management system though efficient utilization of the existing water supplies including the adoption of an effective water reclamation and water reuse program. Reclaimed water could be used to augment existing water supply sources for both non-potable and potable purposes. This introductory paper is part of a series of articles documenting the use of reclaimed water for potable reuse. Topics covered in this introductory paper include: (1) an introduction to the water situation in Iran, (2) identification of the types of potable reuse, (3) presentation of successful potable reuse projects including lessons learned, (4) brief summary of key implementation components of a successful potable reuse program, and (5) special challenges and barriers on implementation of potable reuse in Iran, and (6) the benefits expected from potable reuse program in Iran. Additional information on technical aspects including operations and monitoring, and more detail information on the implementation of water reuse program will be presented in the future articles.
Masoud Kayhanian; George Tchobanoglous. Water reuse in Iran with an emphasis on potable reuse. Scientia Iranica 2016, 23, 1594 -1617.
AMA StyleMasoud Kayhanian, George Tchobanoglous. Water reuse in Iran with an emphasis on potable reuse. Scientia Iranica. 2016; 23 (4):1594-1617.
Chicago/Turabian StyleMasoud Kayhanian; George Tchobanoglous. 2016. "Water reuse in Iran with an emphasis on potable reuse." Scientia Iranica 23, no. 4: 1594-1617.
Harold L Leverenz; Manjunath Akkipeddi; Jerry Marcotte; Gerhard Panuschka; George Tchobanoglous. Development of a low maintenance process for decentralized non-potable water recycling. Proceedings of the Water Environment Federation 2016, 2016, 3095 -3102.
AMA StyleHarold L Leverenz, Manjunath Akkipeddi, Jerry Marcotte, Gerhard Panuschka, George Tchobanoglous. Development of a low maintenance process for decentralized non-potable water recycling. Proceedings of the Water Environment Federation. 2016; 2016 (10):3095-3102.
Chicago/Turabian StyleHarold L Leverenz; Manjunath Akkipeddi; Jerry Marcotte; Gerhard Panuschka; George Tchobanoglous. 2016. "Development of a low maintenance process for decentralized non-potable water recycling." Proceedings of the Water Environment Federation 2016, no. 10: 3095-3102.
Sintana E. Vergara; George Tchobanoglous. Municipal Solid Waste and the Environment: A Global Perspective. Annual Review of Environment and Resources 2012, 37, 277 -309.
AMA StyleSintana E. Vergara, George Tchobanoglous. Municipal Solid Waste and the Environment: A Global Perspective. Annual Review of Environment and Resources. 2012; 37 (1):277-309.
Chicago/Turabian StyleSintana E. Vergara; George Tchobanoglous. 2012. "Municipal Solid Waste and the Environment: A Global Perspective." Annual Review of Environment and Resources 37, no. 1: 277-309.
Russel M. Adams; Harold L. Leverenz; George Tchobanoglous; John Black. Recovery of Energy, Nutrients, and Potable Water from Municipal Wastewater: A Case Study. Proceedings of the Water Environment Federation 2012, 2012, 154 -168.
AMA StyleRussel M. Adams, Harold L. Leverenz, George Tchobanoglous, John Black. Recovery of Energy, Nutrients, and Potable Water from Municipal Wastewater: A Case Study. Proceedings of the Water Environment Federation. 2012; 2012 (17):154-168.
Chicago/Turabian StyleRussel M. Adams; Harold L. Leverenz; George Tchobanoglous; John Black. 2012. "Recovery of Energy, Nutrients, and Potable Water from Municipal Wastewater: A Case Study." Proceedings of the Water Environment Federation 2012, no. 17: 154-168.
The emission rates of greenhouse gases (GHGs) from individual onsite septic systems used for the management of domestic wastewater were determined in this study. A static flux chamber method was used to determine the emission rates of methane, carbon dioxide, and nitrous oxide gases from eight septic tanks and two soil dispersal systems. A technique developed for the measurement of gas flow and concentration at clean-out ports was used to determine the mass flow of gases moving through the household drainage and vent system. There was general agreement in the methane emission rates for the flux chamber and vent system methods. Several sources of variability in the emission rates were also identified. The septic tank was the primary source of methane, whereas the soil dispersal system was the principal source of carbon dioxide and nitrous oxide emissions. Methane concentrations from the soil dispersal system were found to be near ambient concentrations, similarly negligible amounts of nitrous oxide were found in the septic tank. All emissions originating in the soil dispersal system were discharged through the building vent as a result of natural, wind-induced flow. The gaseous emission rate data were determined to be geometrically distributed. The geometric mean and standard deviation (sg) of the total atmospheric emission rates for methane, carbon dioxide, and nitrous oxide based on samples from the vent system were estimated to be 10.7 (sg = 1.65), 335 (sg = 2.13), and 0.20 (sg = 3.62) g/capita·d, respectively. The corresponding total anthropogenic CO2 equivalence (CO2e) of the GHG emissions to the atmosphere, is about 0.1 tonne CO2e/capita·yr. This title belongs to WERF Research Report Series. ISBN: 9781843396161 (Print) ISBN: 9781780403359 (eBook)
Harold L. Leverenz; George Tchobanoglous; Jeannie L. Darby. Evaluation of Greenhouse Gas Emissions from Septic Systems. Water Intelligence Online 2011, 10, 1 .
AMA StyleHarold L. Leverenz, George Tchobanoglous, Jeannie L. Darby. Evaluation of Greenhouse Gas Emissions from Septic Systems. Water Intelligence Online. 2011; 10 ():1.
Chicago/Turabian StyleHarold L. Leverenz; George Tchobanoglous; Jeannie L. Darby. 2011. "Evaluation of Greenhouse Gas Emissions from Septic Systems." Water Intelligence Online 10, no. : 1.
Subsurface drip irrigation systems apply effluent from onsite wastewater systems in a more uniform manner at a lower rate than has been possible with other effluent dispersal methods. The effluent is dispersed in a biologically active part of the soil profile for optimal treatment and where the water and nutrients can be utilized by landscape plants. Container tests were performed to determine the fate of water and nitrogen compounds applied to packed loamy sand, sandy loam, and silt loam soils. Nitrogen removal rates measured in the container tests ranged from 63 to 95% despite relatively low levels of available carbon. A Hydrus 2D vadose zone model with nitrification and denitrification rate coefficients calculated as a function of soil moisture content fit the container test results reasonably well. Model results were sensitive to the denitrification rate moisture content function. Two-phase transport parameters were needed to model the preferential flow conditions in the finer soils. Applying the model to generic soil types, the greatest nitrogen losses (30 to 70%) were predicted for medium to fine texture soils and soils with restrictive layers or capillary breaks. The slow transport with subsurface drip irrigation enhanced total nitrogen losses and plant nitrogen uptake opportunity.
R.A. Beggs; D.J. Hills; G. Tchobanoglous; J.W. Hopmans. Fate of nitrogen for subsurface drip dispersal of effluent from small wastewater systems. Journal of Contaminant Hydrology 2011, 126, 19 -28.
AMA StyleR.A. Beggs, D.J. Hills, G. Tchobanoglous, J.W. Hopmans. Fate of nitrogen for subsurface drip dispersal of effluent from small wastewater systems. Journal of Contaminant Hydrology. 2011; 126 (1-2):19-28.
Chicago/Turabian StyleR.A. Beggs; D.J. Hills; G. Tchobanoglous; J.W. Hopmans. 2011. "Fate of nitrogen for subsurface drip dispersal of effluent from small wastewater systems." Journal of Contaminant Hydrology 126, no. 1-2: 19-28.
As a result of population growth, urbanization, and climate change, public water supplies are becoming stressed, and the chances of tapping new water supplies for metropolitan areas are getting more difficult, if not impossible. As a consequence, existing water supplies must go further. One way to achieve this objective is by increased water reuse, particularly in supplementing municipal water supplies. Although water reuse offers many opportunities it also involves a number of problems. A significant cost for nonpotable water reuse in urban areas is associated with the need to provide separate piping and storage systems for reclaimed water. In most situations, the cost of a dual distribution system has been prohibitive and thus, has limited implementation for water reuse programs. The solution to the problem of distribution is to implement direct potable reuse (DPR) of purified water in the existing water distribution system. The purpose of this paper is to consider (a) a future in which DPR will be the norm and (b) the steps that will need to be taken to make this a reality. Following an overview, the rationale for DPR, some examples of DPR projects, technological and implementation issues, and future expectations are examined.
Harold L. Leverenz; George Tchobanoglous; Takashi Asano. Direct potable reuse: a future imperative. Journal of Water Reuse and Desalination 2011, 1, 2 -10.
AMA StyleHarold L. Leverenz, George Tchobanoglous, Takashi Asano. Direct potable reuse: a future imperative. Journal of Water Reuse and Desalination. 2011; 1 (1):2-10.
Chicago/Turabian StyleHarold L. Leverenz; George Tchobanoglous; Takashi Asano. 2011. "Direct potable reuse: a future imperative." Journal of Water Reuse and Desalination 1, no. 1: 2-10.
Factors that impacts agricultural reuse are examined in the paper. The objective of this work is to assess the factors involved in agriculture reuse by presenting a comparison of three wastewater treatment plants used for food crop irrigation: Adelaide, South Australia; Foggia, South Italy and Monterey, California. An analysis of the driving forces for reuse, regulatory requirements, and other factors affecting the water reuse systems is described. A comparison of treatment technologies and costs is also performed including pretreatments, biological steps, filtration, sedimentation and disinfection options. As a consequence of global warming that has increased the frequency and severity of natural disasters like the drought, the impacts of climate change and seasonality is discussed in the paper. A possible scenario of the future trend for agriculture reuse including the influence of the increase in urban water use, the increase in salinity and the acceptability of products is lastly considered
Ezio Ranieri; Harold Leverenz; George Tchobanoglous. An Examination of the Factors Involved in Agricultural Reuse:Technologies, Regulatory and Social Aspects. Journal of Water Resource and Protection 2011, 03, 300 -310.
AMA StyleEzio Ranieri, Harold Leverenz, George Tchobanoglous. An Examination of the Factors Involved in Agricultural Reuse:Technologies, Regulatory and Social Aspects. Journal of Water Resource and Protection. 2011; 03 (05):300-310.
Chicago/Turabian StyleEzio Ranieri; Harold Leverenz; George Tchobanoglous. 2011. "An Examination of the Factors Involved in Agricultural Reuse:Technologies, Regulatory and Social Aspects." Journal of Water Resource and Protection 03, no. 05: 300-310.
To achieve the water quality goals of the future while avoiding major increases in the cost and carbon footprint of wastewater management, it will be necessary to develop integrated wastewater systems that are able to recover and utilize the energy contained in municipal wastewater. An alternative model for wastewater management systems focused on maximum recovery of chemical energy in the treatment process is presented in this paper. Two complementary strategies for maximizing the net recovery of chemical energy are discussed: (1) aggressive treatment at the front end of the process such that cost-effective benefits in downstream unit processes are realized and (2) collection of solids in their highest energy density condition and thermally converting these solids to achieve maximum energy production potential and highest value residual solids.
Russel M. Adams; Harold L. Leverenz; George Tchobanoglous. Re-Orienting Municipal Wastewater Management Systems for Energy Reduction and Energy Production. Proceedings of the Water Environment Federation 2011, 2011, 89 -97.
AMA StyleRussel M. Adams, Harold L. Leverenz, George Tchobanoglous. Re-Orienting Municipal Wastewater Management Systems for Energy Reduction and Energy Production. Proceedings of the Water Environment Federation. 2011; 2011 (18):89-97.
Chicago/Turabian StyleRussel M. Adams; Harold L. Leverenz; George Tchobanoglous. 2011. "Re-Orienting Municipal Wastewater Management Systems for Energy Reduction and Energy Production." Proceedings of the Water Environment Federation 2011, no. 18: 89-97.
Anoxic subsurface flow (SSF) constructed wetlands were evaluated for denitrification using nitrified wastewater. The treatment wetlands utilized a readily available organic woodchip-media packing to create the anoxic conditions. After 2 years in operation, nitrate removal was found to be best described by first-order kinetics. Removal rate constants at 20 °C (k20) were determined to be 1.41–1.30 d−1, with temperature coefficients (θ) of 1.10 and 1.17, for planted and unplanted experimental woodchip-media SSF wetlands, respectively. First-order removal rate constants decreased as length of operation increased; however, a longer-term study is needed to establish the steady-state values. The hydraulic conductivity in the planted woodchip-media SSF wetlands, 0.13–0.15 m/s, was similar to that measured in an unplanted gravel-media SSF control system.
Harold L. Leverenz; Kristine Haunschild; Guy Hopes; George Tchobanoglous; Jeannie L. Darby. Anoxic treatment wetlands for denitrification. Ecological Engineering 2010, 36, 1544 -1551.
AMA StyleHarold L. Leverenz, Kristine Haunschild, Guy Hopes, George Tchobanoglous, Jeannie L. Darby. Anoxic treatment wetlands for denitrification. Ecological Engineering. 2010; 36 (11):1544-1551.
Chicago/Turabian StyleHarold L. Leverenz; Kristine Haunschild; Guy Hopes; George Tchobanoglous; Jeannie L. Darby. 2010. "Anoxic treatment wetlands for denitrification." Ecological Engineering 36, no. 11: 1544-1551.
Several innovative filtration technologies have been developed in the last two decades to decrease the backwash requirements, to increase the water production efficiency, and to improve the operational and design conditions. The Compressible Medium Filter (CMF) also known as the “Fuzzy Filter” involves the use of a synthetic compressible fiber (polyvaniladene) porous material as the filtering medium instead of conventional granular material. The optimization of the CMF operation is discussed in this paper. Both the CMF removal performance and backwash water ratio (BWR) increase significantly as the medium compression ratio (MCR) is increased. The optimum MCR (for turbidity removal purposes) is the minimum MCR that results in the required degree of turbidity removal to prevent excessive BWR. The optimum MCR for the filtration of conventional activated sludge secondary effluent (for wastewater reuse application) increases from approximately five percent to 25 percent as the average influent turbidity increases from 4 NTU to 7 NTU. The filtration model developed for CMF application can be used to predict the optimum MCR curves for different and more complex filtration conditions. Chemical requirements are also eliminated or minimized with the CMF technology by increasing the MCR when the influent conditions get worse.
O. Caliskaner; G. Tchobanoglous. Optimization of Compressible Medium Filter for Secondary Effluent Filtration. Water Practice and Technology 2009, 4, 1 .
AMA StyleO. Caliskaner, G. Tchobanoglous. Optimization of Compressible Medium Filter for Secondary Effluent Filtration. Water Practice and Technology. 2009; 4 (1):1.
Chicago/Turabian StyleO. Caliskaner; G. Tchobanoglous. 2009. "Optimization of Compressible Medium Filter for Secondary Effluent Filtration." Water Practice and Technology 4, no. 1: 1.
Wastewater management systems are under pressure due to changing economic and environmental conditions. For example, severe water shortages are being experienced in a number of metropolitan areas due to the combined effects of climate change, continued population growth, and over drafting of water supplies. Drought conditions have resulted in rationing of remaining water supplies, conflicts between environmental and agricultural uses of water, increases in the value of water, and restrictions on irrigation and domestic use in urban locations. Many locations throughout the world are expected to experience more frequent and extreme drought conditions in the near future. It is clear that more effective utilization must be made of existing water supplies, especially in urban areas.Other examples of challenges faced by wastewater management systems include the recovery and utilization of energy and the removal of nutrients. In terms of energy, wastewater systems are often identified as large consumers of power and targeted for efficiency upgrades (even though on a per capita basis the power usage is relatively low compared to other uses). Effluent water quality requirements have further increased the power demand as more membrane and high intensity UV systems come online. While anaerobic digestion has been used for sludge management, there is a considerable amount of energy present in wastewater that is currently not utilized and instead places a demand on the aeration system during aerobic treatment. To overcome these challenges, hybrid wastewater systems using satellite facilities in urban areas are being considered.
Harold Leverenz; George Tchobanoglous. Satellite Systems for Enhanced Wastewater Management in Urban Areas. Proceedings of the Water Environment Federation 2009, 2009, 5592 -5608.
AMA StyleHarold Leverenz, George Tchobanoglous. Satellite Systems for Enhanced Wastewater Management in Urban Areas. Proceedings of the Water Environment Federation. 2009; 2009 (10):5592-5608.
Chicago/Turabian StyleHarold Leverenz; George Tchobanoglous. 2009. "Satellite Systems for Enhanced Wastewater Management in Urban Areas." Proceedings of the Water Environment Federation 2009, no. 10: 5592-5608.