scholarly journals Energy consumption of agitators in activated sludge tanks – actual state and optimization potential

2017 ◽  
Vol 77 (3) ◽  
pp. 800-808 ◽  
Author(s):  
K. Füreder ◽  
K. Svardal ◽  
W. Frey ◽  
H. Kroiss ◽  
J. Krampe
Keyword(s):  
Energy Consumption ◽  
Power Density ◽  
Specific Energy ◽  
Operating Time ◽  
Specific Energy Consumption ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Actual State ◽  
Total Energy Consumption ◽  
Continuous Mixing

Abstract Depending on design capacity, agitators consume about 5 to 20% of the total energy consumption of a wastewater treatment plant. Based on inhabitant-specific energy consumption (kWh PE120−1 a−1; PE120 is population equivalent, assuming 120 g chemical oxygen demand per PE per day), power density (W m−3) and volume-specific energy consumption (Wh m−3 d−1) as evaluation indicators, this paper provides a sound contribution to understanding energy consumption and energy optimization potentials of agitators. Basically, there are two ways to optimize agitator operation: the reduction of the power density and the reduction of the daily operating time. Energy saving options range from continuous mixing with low power densities of 1 W m−3 to mixing by means of short, intense energy pulses (impulse aeration, impulse stirring). However, the following correlation applies: the shorter the duration of energy input, the higher the power density on the respective volume-specific energy consumption isoline. Under favourable conditions with respect to tank volume, tank geometry, aeration and agitator position, mixing energy can be reduced to 24 Wh m−3 d−1 and below. Additionally, it could be verified that power density of agitators stands in inverse relation to tank volume.

Fouling of reverse osmosis and nanofiltration membranes by diary industry effluents

2002 ◽  
Vol 45 (12) ◽  
pp. 355-360 ◽  
Author(s):  
M. Turan ◽  
A. Ates ◽  
B. Inanc
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Biological Treatment ◽  
Specific Energy Consumption ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Total Hardness ◽  
Feed Tank ◽  
Layer Resistance

Fouling experiments of nanofiltration (NF) and reverse osmosis (RO) are reported for treatment of the effluent of chemical-biological treatment plant and the original effluent of dairy industry respectively. In the experiments, a thin film composite type of spiral wound was used and fitted with flowmeters and pressure sensors. The feed water was stored into a feed tank and passed a fine filter and was pumped to membrane. Brine and permeate were recirculated back to the feed tank. Membrane fouling was investigated with 16 and 30% water recovery of a single membrane at different pressures and flowrates for RO and NF membranes respectively. Fouling is evaluated with a relationship between relative flux (J/Jo) which is the ratio of the flux at any time during the fouling test to the initial flux and relative resistance (Rf/Rm) which is the ratio of fouling (cake) layer resistance to clean membrane resistance. Turbidity, conductivity, chemical oxygen demand (COD), total suspended solids (TSS) and total hardness were measured in the feed and permeate side of each membrane. The effluent total hardness concentrations of chemical-biological treatment plant were found greater than the influents. The results are presented in terms of the relative flux as a function of time related to hydrodynamic conditions and pollution characteristics of wastewater. The permeate water flux of RO membrane decreases more rapidly than NF membrane. the relative flux decreases with increasing the fouling layer resistance, Rf onto membrane surface. 50% the drop of permeate flux was observed for RO and NF membranes after 50 h and 80 h of operation, respectively. The fouling rate increases with an increase in the concentration of the wastewater constituents in the dairy industry. The relative flux decreased 10 and 20% with increasing chemical oxygen demand (COD) from 5,000 mgl−1 to 10,000 mgl−1 and from 45 mgl−1 to 450 mgl−1 for RO and NF membranes, respectively after 45 h of time. Fouling of membranes resulted in 100% increase of specific energy consumption as the relative permeate fluxes of NF and RO membranes decreased 30 and 40% respectively. The average of specific energy consumption was obtained at 6 and 10 kWhm−3; consequently, operational costs were estimated at U.S. $0.45 m−3 and U.S. $0.75 m−3 for NF and RO units respectively. Also, operational cost for chemical-biological treatment was found at U.S. $0.30 m−3.

scholarly journals Trade-Off between Operating Time and Energy Consumption in Pulsed Electric Field Electrodialysis: A Comprehensive Simulation Study

Membranes ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 43
Author(s):  
Manuel César Martí-Calatayud ◽  
Mario Sancho-Cirer Poczatek ◽  
Valentín Pérez-Herranz
Keyword(s):  
Energy Consumption ◽  
Electric Field ◽  
Simulation Study ◽  
Specific Energy ◽  
Operating Time ◽  
Specific Energy Consumption ◽  
Threshold Value ◽  
Pulsed Electric Field ◽  
Pulse Frequency ◽  
Time And Energy

Electrodialysis (ED) has been recently introduced in a variety of processes where the recovery of valuable resources is needed; thus, enabling sustainable production routes for a circular economy. However, new applications of ED require optimized operating modes ensuring low energy consumptions. The application of pulsed electric field (PEF) electrodialysis has been demonstrated to be an effective option to modulate concentration polarization and reduce energy consumption in ED systems, but the savings in energy are usually attained by extending the operating time. In the present work, we conduct a comprehensive simulation study about the effects of PEF signal parameters on the time and energy consumption associated with ED processes. Ion transport of NaCl solutions through homogeneous cation-exchange membranes is simulated using a 1-D model solved by a finite-difference method. Increasing the pulse frequency up to a threshold value is effective in reducing the specific energy consumption, with threshold frequencies increasing with the applied current density. Varying the duty cycle causes opposed effects in the time and energy usage needed for a given ED operation. More interestingly, a new mode of PEF functions with the application of low values of current during the relaxation phases has been investigated. This novel PEF strategy has been demonstrated to simultaneously improve the time and the specific energy consumption of ED processes.

scholarly journals Electrocoagulation for spent coolant from machinery industry

2017 ◽  
Vol 8 (4) ◽  
pp. 497-506 ◽  
Author(s):  
W. Pantorlawn ◽  
T. Threrujirapapong ◽  
W. Khanitchaidecha ◽  
D. Channei ◽  
A. Nakaruk
Keyword(s):  
Energy Consumption ◽  
Current Density ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Industrial Wastes ◽  
Electrolysis Time ◽  
Current Densities ◽  
Sludge Production

Abstract Spent coolant is considered as one of the most polluting industrial wastes and causes environmental problems. It mostly contains high non-biodegradable organic carbon and oil contents; the biodegradability index was very low at 0.04, which is difficult to be effectively treated by common treatment systems. Electrocoagulation (EC) was proposed for a pre-treatment of coolant. The laboratory-scale of EC reactor was developed with Al electrodes and 10 mm of interelectrodes. The efficiency of the EC reactor on chemical oxygen demand (COD) removal was investigated at various current densities and electrolysis times. The highest current density of 50 mA/cm2 induced a short electrolysis time of 10 min to reach the steady state of approximately 65% COD removal. When lower current densities of 20–40 mA/cm2 were supplied to the EC reactor, COD removal efficiency of 65% can be achieved at longer electrolysis times. According to the specific energy consumption and sludge production, the optimal condition for spent coolant treatment was the current density of 20 mA/cm2 and electrolysis time of 30 min in which a COD removal of efficiency of 68% was obtained, 0.88 kWh/kg-COD of the specific energy consumption and 0.04 kg/kg-COD of the sludge production.

scholarly journals Evaluasi Kinerja Efisiensi Energi Mesin Bubut Melalui Penilaian Indikasi Specific Energy Consumption

2021 ◽  
Vol 9 (2) ◽  
pp. 389
Author(s):  
HERMAN BUDI HARJA ◽  
MOHAMMAD FAUZI ◽  
ASEP FATHAN
Keyword(s):  
Energy Consumption ◽  
Data Envelopment Analysis ◽  
Specific Energy ◽  
Specific Energy Consumption ◽  
Reference Value ◽  
Machining Process ◽  
Data Envelopment ◽  
Total Energy Consumption ◽  
Study Results ◽  
Belt Transmission

ABSTRAKKondisi ketidakselarasan sistem transmisi pulley-belt pada mesin bubut berpengaruh terhadap nilai inefisiensi konsumsi energi mesin perkakas. Penelitian ini bertujuan untuk melakukan kajian evaluasi kinerja efisiensi energi mesin bubut pada kondisi sistem transmisi pulley-belt mesin yang selaras dan tidak selaras. Kajian ini menggunakan metoda penilaian indikasi specific energy consumption (SEC) dari proses pemesinan bubut. Nilai total konsumsi energi saat proses pemotongan diukur menggunakan power analyzer, dan diolah menjadi nilai data SEC, kemudian dianalisis menggunakan Data Envelopment Analysis untuk mendapatkan harga referensi. Penilaian skor penurunan energi setiap mesin diperoleh dengan membandingkan jarak nilai SEC setiap mesin terhadap nilai referensi. Obyek penelitian menggunakan lima buah mesin bubut uji berkapasitas daya medium. Hasil kajian menunjukkan bahwa pada kondisi ketidakselarasan sistem transmisi pulley-belt menyebabkan terjadinya inefisiensi energi mesin bubut sebesar 5%.Kata kunci: Data Envelopment Analysis ,efisiensi energi, ketidakselarasan, SEC ABSTRACTThe pulley belt transmission system's misalignment condition on turning machine affects the low-efficiency value of machine tool energy consumption. This study aims to evaluate the energy efficiency of a lathe in the alignment and misalignment of the pulley-belt transmission system. This study used a method of assessing the specific energy consumption (SEC) of the lathe machining process. During the cutting process, the total energy consumption value is measured using a power analyzer and processed into SEC data values, then analyzed using Data Envelopment Analysis to obtain a reference value. The assessment is obtained by comparing the distance between each machine's SEC value and the reference value. The case study's object was conducted on five test lathes with medium power capacity. The study results show that the pulleybelt transmission system's misalignment causes the lathe's energy inefficiency of more than 5%.Keywords: Data Envelopment Analysis, efficiency energy, misalignment, SEC

scholarly journals Electrooxidation Using Nb/BDD as Post-Treatment of a Reverse Osmosis Concentrate in the Petrochemical Industry

2019 ◽  
Vol 16 (5) ◽  
pp. 816 ◽  
Author(s):  
Salatiel Wohlmuth da Silva ◽  
Carla Venzke ◽  
Júlia Bitencourt Welter ◽  
Daniela Schneider ◽  
Jane Zoppas Ferreira ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Reverse Osmosis ◽  
Specific Energy ◽  
Energy Requirement ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Inorganic Ions ◽  
Oxidation Time ◽  
Kinetic Regime ◽  
Boron Doped Diamond

This work evaluated the performance of an electrochemical oxidation process (EOP), using boron-doped diamond on niobium substrate (Nb/BDD), for the treatment of a reverse osmosis concentrate (ROC) produced from a petrochemical wastewater. The effects of applied current density (5, 10, or 20 mA·cm−2) and oxidation time (0 to 5 h) were evaluated following changes in chemical oxygen demand (COD) and total organic carbon (TOC). Current efficiency and specific energy consumption were also evaluated. Besides, the organic byproducts generated by EOP were analyzed by gas chromatography coupled to mass spectrometry (GC–MS). The results show that current densities and oxidation time lead to a COD and TOC reduction. For the 20 mA·cm−2, changes in the kinetic regime were found at 3 h and associated to the oxidation of inorganic ions by chlorinated species. After 3 h, the oxidants act in the organic oxidation, leading to a TOC removal of 71%. Although, due to the evolution of parallel reactions (O2, H2O2, and O3), the specific energy consumption also increased, the resulting consumption value of 66.5 kW·h·kg−1 of COD is considered a low energy requirement representing lower treatment costs. These results encourage the applicability of EOP equipped with Nb/BDD as a treatment process for the ROC.

Specific energy consumption of membrane bioreactor (MBR) for sewage treatment

2012 ◽  
Vol 65 (2) ◽  
pp. 380-392 ◽  
Author(s):  
Pawel Krzeminski ◽  
Jaap H. J. M. van der Graaf ◽  
Jules B. van Lier
Keyword(s):  
Energy Consumption ◽  
Specific Energy ◽  
Sewage Treatment ◽  
Specific Energy Consumption ◽  
Electric Energy ◽  
Hollow Fibre ◽  
Reactor Performance ◽  
Operational Parameters ◽  
Total Energy Consumption ◽  
Membrane Area

This paper provides an overview of current electric energy consumption of full-scale municipal MBR installations based on literature review and case studies. Energy requirements of several MBRs were linked to operational parameters and reactor performance. Total and specific energy consumption data were analysed on a long-term basis with special attention given to treated flow, design capacity, membrane area and effluent quality. The specific energy consumption of an MBR system is dependent on many factors, such as system design and layout, volume of treated flow, membrane utilization and operational strategy. Operation at optimal flow conditions results in a low specific energy consumption and energy efficient process. Energy consumption of membrane related modules was in the range of 0.5–0.7 kWh/m3 and specific energy consumption for membrane aeration in flat sheet (FS) was 33–37% higher than in a hollow fibre (HF) system. Aeration is a major energy consumer, often exceeding 50% share of total energy consumption. In consequence, coarse bubble aeration applied for continuous membrane cleaning remains the main target for energy saving actions. Also, a certain potential for energy optimization without immediate danger of affecting the quality of the produced effluent was observed.

Design and operating experiences of full-scale municipal membrane bioreactors in Japan

2014 ◽  
Vol 69 (5) ◽  
pp. 1088-1093 ◽  
Author(s):  
H. Itokawa ◽  
K. Tsuji ◽  
K. Yamashita ◽  
T. Hashimoto
Keyword(s):  
Energy Consumption ◽  
Specific Energy ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Specific Energy Consumption ◽  
Oxygen Demand ◽  
Cost Evaluation ◽  
Guidance System ◽  
Small Scale ◽  
Municipal Wastewater Treatment

In Japan, membrane bioreactor (MBRs) have been installed in 17 small-scale municipal wastewater treatment plants (WWTPs) in the past 8 years, together with two recently installed MBRs for larger-scale WWTPs. In this study, design and operating data were collected from 17 of them as part of a follow-up survey, and aspects including system design, biological treatment, membrane operation, problems and costs were overviewed. Because most of the MBRs were designed according to standardized guidance, system configuration of the plants was similar; pre-denitrification using the Modified Ludzack-Ettinger (MLE) process with membrane units submerged in aerobic tanks, following a fine screen and flow equalization tank. This led to effluent quality with biochemical oxygen demand and T-N of less than 3.5 and 7.4 mg/L, respectively, for nine plants on an annual average basis. It was a common practice in extremely under-loaded plants to operate the membrane systems intermittently. Frequency of recovery cleaning events was plant-specific, mostly ranging from 1 to 5 times/year. Cost evaluation revealed that specific construction costs for the small-scale MBRs were no more than for oxidation ditch plants. Although specific energy consumption values tended to be high in the under-loaded plants, the demonstration MBR, where several energy reducing measures had been incorporated, attained specific energy consumption of 0.39 kWh/m3 under full-capacity operation.

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