Tertiary nitrification in aerated pilot biofilters

1994 ◽  
Vol 29 (10-11) ◽  
pp. 53-60 ◽  
Author(s):  
M. Tschui ◽  
M. Boller ◽  
W. Gujer ◽  
J. Eugster ◽  
C. Mäder ◽  
...  
Keyword(s):  
Pilot Scale ◽  
Operating Conditions ◽  
Nitrification Rate ◽  
Measured Temperature ◽  
Exponential Relationship ◽  
Effluent Quality ◽  
Different Types ◽  
Long Term Performance ◽  
Term Performance

Three different types of internally aerated pilot scale biofilters were operated as tertiary nitrification systems. Long-term performance of the three aerated biofilters was tested under various operating conditions. The maximum volumetric nitrification rates under non NH4-limiting conditions for the three aerated biofilter systems were investigated. Based on measured temperature dependencies, an exponential relationship was established enabling the prediction of the nitrification rates at desired temperatures. Based on a temperature of 10°C, the results allow a comparison between the surface and volume specific nitrification rates in the tested biofilters as a function of the NH4 effluent concentration. As shown by experiments, nitrification performance depends on water as well as air velocities in the filter. Higher velocities of both air and water increase the nitrification rate. However, they also increase the head loss and thus decrease the filter run time. Therefore, the optimal operating conditions depend also on the filter media and the required effluent quality. Compared to fully O2-limiting operating conditions, nitrification performance during a period under partially NH4-limiting conditions clearly decreased in all tested biofilters.

scholarly journals Intelligent long-term performance analysis in power electronics systems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Saeed Peyghami ◽  
Tomislav Dragicevic ◽  
Frede Blaabjerg
Keyword(s):  
Performance Indicator ◽  
Thermal Characteristics ◽  
Operating Conditions ◽  
System Level ◽  
Power Electronic ◽  
Reliability Modeling ◽  
Artificial Neural Network Ann ◽  
Long Term Performance ◽  
Term Performance

AbstractThis paper proposes a long-term performance indicator for power electronic converters based on their reliability. The converter reliability is represented by the proposed constant lifetime curves, which have been developed using Artificial Neural Network (ANN) under different operating conditions. Unlike the state-of-the-art theoretical reliability modeling approaches, which employ detailed electro-thermal characteristics and lifetime models of converter components, the proposed method provides a nonparametric surrogate model of the converter based on limited non-linear data from theoretical reliability analysis. The proposed approach can quickly predict the converter lifetime under given operating conditions without a further need for extended, time-consuming electro-thermal analysis. Moreover, the proposed lifetime curves can present the long-term performance of converters facilitating optimal system-level design for reliability, reliable operation and maintenance planning in power electronic systems. Numerical case studies evaluate the effectiveness of the proposed reliability modeling approach.

Investigation of long-term operation and biomass activity in a membrane bioreactor system

2011 ◽  
Vol 63 (9) ◽  
pp. 1906-1912 ◽  
Author(s):  
Simos Malamis ◽  
Andreas Andreadakis ◽  
Daniel Mamais ◽  
Constantinos Noutsopoulos
Keyword(s):  
Membrane Fouling ◽  
Membrane Bioreactor ◽  
Extracellular Polymeric Substances ◽  
Operating Conditions ◽  
Term Operation ◽  
Solids Retention ◽  
Biomass Activity ◽  
Long Term Performance ◽  
Term Performance

The aim of this work was to evaluate the long-term performance of a Membrane Bioreactor (MBR) that operated continuously for 2.5 years and to assess membrane fouling and biomass activity under various operating conditions. Furthermore, a method for the characterisation of influent wastewater was developed based on its separation into various fractions. The MBR system operated at the solids retention times (SRT) of 10, 15, 20 and 33 days. The increase of SRT resulted in a decrease of the fouling rate associated with the reduction of extracellular polymeric substances. Moreover, the SRT increase resulted in a significant reduction of the Oxygen Uptake Rate (OUR) due to the lower availability of substrate and in a notable decrease of the maximum OUR since high SRT allowed the development of slower growing microorganisms. Biomass consisted of small flocs due to extensive deflocculation caused by intense aeration. Finally, the method developed for wastewater characterisation is straightforward and less time consuming than the usual method that is employed.

Advanced Techniques for Establishing Long-Term Performance of Composite Repair Systems

2014 ◽  
Author(s):  
Chris Alexander
Keyword(s):  
The United States ◽  
Operating Conditions ◽  
Repair System ◽  
Composite Repair ◽  
Design Life ◽  
Repair Systems ◽  
Long Term Performance ◽  
Term Performance ◽  
Composite Repairs

Although composite materials are used to repair and reinforce a variety of anomalies in high pressure transmission gas and liquid pipelines, there continues to be widespread debate regarding what constitutes a long-term composite repair. The United States regulations require that composite repairs must be able to permanently restore the serviceability of the repaired pipeline, while in contrast the Canadian regulations take a more prescriptive approach by integrating the ASME PCC-2 and ISO 24817 composite repair standards along with a requirement for establishing a 50-year design life. In this paper the author provides a framework for what should be considered in qualifying a composite repair system for long-term performance by focusing on the critical technical aspects associated with a sound composite repair. The presentation includes a discussion on establishing an appropriate composite design stress using the existing standards, using full-scale testing to ensure that stresses in the repair do not exceed the designated composite design stresses, and guidance for operators in how to properly integrate their pipeline operating conditions to establish a design life. By implementing the recommendations presented in this paper, operators will be equipped with a resource for objectively evaluating the composite repair systems used to repair their pipeline systems.

Long-term Performance Analysis of CdTe PV module in real operating conditions

2018 ◽  
Vol 5 (11) ◽  
pp. 23210-23217 ◽  
Author(s):  
Rahul Rawat ◽  
S.C. Kaushik ◽  
O.S. Sastry ◽  
Birinchi Bora ◽  
Y.K. Singh
Keyword(s):  
Performance Analysis ◽  
Operating Conditions ◽  
Pv Module ◽  
Long Term Performance ◽  
Term Performance

Hot Mix Asphalt Rubber Applications in Virginia

1996 ◽  
Vol 1530 (1) ◽  
pp. 18-24 ◽  
Author(s):  
G. W. Maupin
Keyword(s):  
Department Of Transportation ◽  
Short Term ◽  
Ground Tire Rubber ◽  
Asphalt Rubber ◽  
Evaluation Time ◽  
Different Types ◽  
Virginia Department ◽  
Long Term Performance ◽  
Term Performance

Four test sections using asphalt rubber hot mix were placed in Virginia from 1990 to 1993. These installations were to familiarize contractors and Virginia Department of Transportation personnel with the construction process and compare the performance of different types of mixes containing ground tire rubber. The MacDonald and Rouse wet processes were used successfully. Dense graded surface mixes, a gap-graded surface mix, and a base mix were manufactured. A stress-absorbing membrane interlayer was also used on one project in an attempt to deter or eliminate various types of cracking. The asphalt rubber mixes have performed as well as the conventional mixes over the short term. More evaluation time is needed to determine if long-term performance of the asphalt rubber mixes is superior to conventional mixes. The asphalt rubber mixes cost 64 to 102 percent more than conventional mixes. This cost would probably decrease if substantial quantities were placed.

Sign in / Sign up

Export Citation Format

Share Document