scholarly journals ENHANCED PERFORMANCE OF MULTI-STAGE ANAEROBIC DIGESTION OF TOFU WASTEWATER: ROLE OF RECIRCULATION

2019 ◽  
Vol 10 (1) ◽  
pp. 29-37 ◽  
Author(s):  
Hanny Vistanty ◽  
Rizal Awaluddin Malik
Keyword(s):  
Anaerobic Digestion ◽  
Ph Value ◽  
Anaerobic Reactors ◽  
Multi Stage ◽  
Recirculation System ◽  
In Series ◽  
And Performance ◽  
Anaerobic System

Continuous three-stage anaerobic reactors with recirculation system were employed to treat real tofu wastewater. The system consists of 3 reactors connected in series and effluent of the last reactor was partly returned as feed of the first reactor along with fresh wastewater. The recirculation system was conducted on four variations of recirculation ratio (RR)s of 0, 1.0, 1.3, and 1.5 to evaluate the influence of recirculation on stability and performance of anaerobic system. Results showed that recirculation improved the performance of anaerobic digestion. COD was fluctuated without recirculation and gradually decreased to 373 and 298 mg/L at RR 1.3 and 1.5, respectively. Likewise, pH value was dropped to 6.5 at RR 0, and started to increase to approximately 8.0 upon employing recirculation. In addition, the system also showed excellent toleration against rise in ammonia loading, with effluent ammonia approximately 4.678 mg/L. The findings showed that the system employed had excellent efficiency and stability in treating tofu wastewater. 

Performances of Leaching-UBF Anaerobic Digestion for Biogas Production of Kitchen Waste

2014 ◽  
Vol 878 ◽  
pp. 489-495
Author(s):  
Feng Kong ◽  
Xiao Ye Zhang ◽  
Jie Hong Cheng ◽  
Zai Xin Mao ◽  
Yong Qiang Wang ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acid ◽  
Ph Value ◽  
Biogas Production ◽  
Production Performance ◽  
Kitchen Waste ◽  
Gas Generation ◽  
Methane Fermentation ◽  
Parameter Variations ◽  
Anaerobic System

The performances of leaching-upflow blanket filter (UBF) anaerobic digestion for biogas production of kitchen waste was investigated. To find out the process parameter variations of acidification phase and the methane production performance of methanogenic phase, kitchen waste from division of environment sanitation management of Changzhou was used as feedstock. The results show that the ammonia in anaerobic system cumulated continuously throughout the digestion; pH value maintained at7.6; At first the value of COD ranged from 20000 mg/L to 140000 mg/L to the final UBF water 10000mg/L to 12000 mg/L; Volatile fatty acid (VFA) reduced to 150mg/L with the increase of the days; total nitrogen increases first and then decreases, finally, it keeps at 1600 mg/L; The concentration of alkalinity increased slightly; biogas production is stable, The rate of gas generation is above0.30 m3/kgCOD . These results provide a proof of the feasibility for kitchen waste anaerobic methane fermentation.

The role of the pH value in water-based pastes on the processing and performance of Ni-rich LiNi0.5Mn0.3Co0.2O2 based positive electrodes

2020 ◽  
Vol 475 ◽  
pp. 228608 ◽  
Author(s):  
Lukas Ibing ◽  
Tobias Gallasch ◽  
Alex Friesen ◽  
Philip Niehoff ◽  
Andreas Hintennach ◽  
...  
Keyword(s):  
Ph Value ◽  
Positive Electrodes ◽  
Water Based ◽  
And Performance

Biogas Production from Cassava Waste Cake in a Two-Stage Anaerobic Digestion System

2012 ◽  
Vol 512-515 ◽  
pp. 351-355 ◽  
Author(s):  
Phongphan Promphiphak ◽  
Tanakorn Wongwuttanasatian
Keyword(s):  
Anaerobic Digestion ◽  
Energy Production ◽  
Ph Value ◽  
Biogas Production ◽  
Pilot Scale ◽  
Organic Loading Rate ◽  
Net Energy ◽  
Two Stage ◽  
In Series ◽  
Cassava Waste

This research is to produce biogas by using cassava waste cake as a feed stock in a two-stage anaerobic digestion system. The system was designed and built as a pilot-scale plant consisting of mixing tank, a fermented acid tank, two methanogenic tanks and a storage tank connecting in series. Feed stocks were mixed in the mixing tank and then fed into the fermented acid tank. The feeding was a batch feeding with a hydraulic retention time of 12 days. The system was operated to determine the biogas production rate and the net energy production. The temperature of the fermented tanks were set at 35°C during the testing period. The pH value was initially set at 8. The organic loading rate was at 0.417 g COD/ L-day. The results showed that the system can produce biogas at a rate of 140 L/day in average. The net energy production was found to be 48.52 W-h/day.

scholarly journals Employee Engagement, Organisational Commitment and Performance of Selected State Corporations in Kenya

2017 ◽  
Vol 13 (31) ◽  
pp. 317 ◽  
Author(s):  
Stephen G. Cheche ◽  
Stephen M.A. Muathe ◽  
Samuel M. Maina
Keyword(s):  
Employee Engagement ◽  
Sampling Strategy ◽  
Organisational Commitment ◽  
Organisational Performance ◽  
Mediating Role ◽  
Multi Stage ◽  
The Republic ◽  
And Performance ◽  
The Relationship

The influence of employee engagement on organisational performance has been widely acknowledged and confirmed. However, there are scanty empirical investigations on the mediating role of organisational commitment on the relationship between employee engagement and organisational performance. Therefore, this study sought to investigate the mediating influence of organisational commitment on the relationship between employee engagement and performance of selected state corporations in Kenya. The study adopted a positivistic approach to investigate the relationships among and between the variables. Descriptive and explanatory research designs were used to describe the variables and establish the nature of the relationships among them. The study is based on employees of state corporations in research and training in the republic of Kenya. A sample of 378 respondents was selected using a multi stage sampling strategy. Data was analysed using descriptive and inferential statistics. The result indicates that employee engagement influences organisational performance and that the relationship is partially moderated by organisational commitment.

The role of SSVF and SSHF beds in concentrated wastewater treatment, design recommendation

2011 ◽  
Vol 64 (2) ◽  
pp. 431-439 ◽  
Author(s):  
M. Gajewska ◽  
H. Obarska-Pempkowiak
Keyword(s):  
Sewage Sludge ◽  
Treatment Wetland ◽  
Sludge Dewatering ◽  
Reject Water ◽  
Effective Removal ◽  
In Series ◽  
And Performance ◽  
Design Recommendation ◽  
Final Effluent

The return flows of reject water from sewage sludge dewatering alter the activated sludge process in a conventional WWTP and increase TN concentration in the final effluent from WWTP. The objective of the investigation carried out was to consider the application of multistage treatment wetland (MTW) for the treatment of reject water from sewage sludge dewatering in a centrifuge (RWC). This paper aims to present the design and performance of each stage of the treatment as well as the efficiency of total MTW. The full scale pilot plant for RWC, consisting of two vertical flow beds (SS VF) working in series, followed by an horizontal flow bed (SS HF), was built in 2008. The applied configuration ensured a very high removal efficiency of principal pollutant (COD – 76.0% and NH4+-N – 93.6%). In the investigated facilities, the SS VF beds ensured an effective removal of nitrogen compounds, especially NH4+-N, whereas the decomposition of hardly degradable Org-N and COD took place in SS HF. This research illustrates that the MTW could be successfully applied for the treatment of RWC.

Treatment of Bleaching Effluents in Aerobic/Anaerobic Fluidized Biofilm Systems

1991 ◽  
Vol 24 (3-4) ◽  
pp. 179-187 ◽  
Author(s):  
M. Fahmy ◽  
E. Heinzle ◽  
O. M. Kut
Keyword(s):  
Anaerobic Conditions ◽  
Anaerobic Reactors ◽  
In Series ◽  
Aerobic Reactor ◽  
Recycle Reactor ◽  
One Year ◽  
Aerobic And Anaerobic ◽  
Global Parameters ◽  
Aerobic And Anaerobic Conditions ◽  
Anaerobic System

Biodegradation of chloroorganic compounds in real industrial bleaching effluents (chlorination and extraction), with adapted biofilm in fluidized sand bed reactors, was studied under aerobic and anaerobic conditions. The effluents were only diluted and supplied with mineral nutrients. Two reactor combinations were compared with a single stage aerobic digestor (AFB). In the anaerobic-aerobic reactors in series (AAS), the effluents were first treated anaerobically followed by an aerobic reactor in a single pass. In the anaerobic-aerobic recycle reactor (AAR), the reactor content was periodically moving back from aerobic to anaerobic fluidized beds. The reactors were running continuously for one year. The most significant differences observed were between aerobic and anaerobic single reactors. Generally anaerobiosis reduced performance in terms of global parameters (COD, NPOC, AOX). With a residence time of 18 h for each reactor, COD and AOX typically decreased by 15-32 % for each aerobic reactor system (AFB, AAS, AAR), whereas a decrease of typically 4-15 % was observed in the purely anaerobic system. From GC and GC/MS analysis it was evident that in the anaerobic reactors, 2,4,6-trichlorophenol was first converted to 2,4-dichlorophenol. In all three systems 2,4,6-trichlorophenol and dichlorophenols were almost completely removed.

Organic material solubilization of domestic primary sludge in anaerobic digestion at controlled pH

2003 ◽  
Vol 48 (4) ◽  
pp. 195-198 ◽  
Author(s):  
C. Yangin Gomec ◽  
R.E. Speece
Keyword(s):  
Anaerobic Digestion ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Primary Sludge ◽  
Anaerobic Reactors ◽  
Ph Influence ◽  
Soluble Organic Carbon ◽  
Soluble Chemical Oxygen Demand ◽  
Ph Controlled

The role of the pH in the anaerobic digestion of domestic primary sludge at mesophilic temperature was evaluated. Since solubilization of organic materials is seriously affected by pH, much research has been performed for the evaluation of significant pH influence on the production of soluble organic carbon in the acid phase. In this study, the performance of continuously stirred anaerobic reactors for the production of soluble chemical oxygen demand (SCOD) and volatile fatty acids (VFAs) in domestic primary sludge was investigated. In the first anaerobic reactor, the pH was not controlled (pH-uncontrolled) whereas the pH was fixed at 6.5 (pH-controlled) in the second reactor. Two sets were performed. Results of both sets indicated that, VSS was removed with a corresponding production of VFAs and SCOD in both reactors. However, production of VFAs and SCOD stopped earlier in the pH-controlled reactors. Methanogenic phase started to operate at earlier times whereas hydrolysis and fermentation were still operating in the pH-uncontrolled reactors. The process stability and efficiency of anaerobic digestion of substrates such as domestic primary sludge can be improved by anaerobic digestion elutriated phased treatment (ADEPT) in which the acid elutriation reactor and methanogenic reactor are separated. In this respect, ADEPT was introduced.

Trace nanoanalysis

1994 ◽  
Vol 52 ◽  
pp. 940-941
Author(s):  
D. E. Newbury ◽  
R. D. Leapman
Keyword(s):  
High Performance ◽  
Secondary Ion Mass Spectrometry ◽  
Detection Efficiency ◽  
Volume Element ◽  
And Performance ◽  
Trace Constituents ◽  
Secondary Ion ◽  
Concentration Levels ◽  
Structure Properties

Trace constituents, which can be very loosely defined as those present at concentration levels below 1 percent, often exert influence on structure, properties, and performance far greater than what might be estimated from their proportion alone. Defining the role of trace constituents in the microstructure, or indeed even determining their location, makes great demands on the available array of microanalytical tools. These demands become increasingly more challenging as the dimensions of the volume element to be probed become smaller. For example, a cubic volume element of silicon with an edge dimension of 1 micrometer contains approximately 5×1010 atoms. High performance secondary ion mass spectrometry (SIMS) can be used to measure trace constituents to levels of hundreds of parts per billion from such a volume element (e. g., detection of at least 100 atoms to give 10% reproducibility with an overall detection efficiency of 1%, considering ionization, transmission, and counting).

The Relation Between Financial Incentives, Motivation, and Performance

2017 ◽  
Vol 16 (2) ◽  
pp. 61-76 ◽  
Author(s):  
Anaïs Thibault Landry ◽  
Marylène Gagné ◽  
Jacques Forest ◽  
Sylvie Guerrero ◽  
Michel Séguin ◽  
...  
Keyword(s):  
Financial Incentives ◽  
Work Performance ◽  
Autonomous Motivation ◽  
Compensation Plans ◽  
Work Settings ◽  
Path Analyses ◽  
Three Samples ◽  
And Performance ◽  
Performance Results

Abstract. To this day, researchers are debating the adequacy of using financial incentives to bolster performance in work settings. Our goal was to contribute to current understanding by considering the moderating role of distributive justice in the relation between financial incentives, motivation, and performance. Based on self-determination theory, we hypothesized that when bonuses are fairly distributed, using financial incentives makes employees feel more competent and autonomous, which in turn fosters greater autonomous motivation and lower controlled motivation, and better work performance. Results from path analyses in three samples supported our hypotheses, suggesting that the effect of financial incentives is contextual, and that compensation plans using financial incentives and bonuses can be effective when properly managed.

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