Effects of mixing on anaerobic treatment of potato-processing wastewater

1991 ◽  
Vol 18 (3) ◽  
pp. 504-514 ◽  
Author(s):  
K. C. Lin ◽  
M. E. J. Pearce
Keyword(s):  
Steady State ◽  
Methane Production ◽  
Anaerobic Treatment ◽  
Joint Effect ◽  
Potato Processing ◽  
Anaerobic Reactors ◽  
Mixing Effects ◽  
Mixing Intensity ◽  
Solids Removal ◽  
Steady State Performance

Four laboratory-scale reactors were used to study the effects of mixing intensity and mixing duration on the anaerobic treatment of potato-processing wastewater at 20 °C. The mixing intensities were set at impeller speeds of 0, 20, 50, and 100 rpm. Two mixing durations were studied: 45 and 15 min/h. It was found that both mixing intensities and mixing durations studied and their joint effect significantly affected the steady-state performance of the anaerobic reactors in treating the potato-processing wastewater with respect to organics and solids removals and methane production. Key words: mixing effects, anaerobic treatment, potato-processing wastewater, organics and solids removal, methane production.

Feasibility tests for treating shampoo and hair colorant wastewaters using anaerobic processes

2012 ◽  
Vol 65 (2) ◽  
pp. 303-308 ◽  
Author(s):  
Shaikh Z. Ahammad ◽  
A. Yakubu ◽  
J. Dolfing ◽  
C. Mota ◽  
D. W. Graham
Keyword(s):  
Methane Production ◽  
Biological Treatment ◽  
Anaerobic Treatment ◽  
Energy Costs ◽  
Net Energy ◽  
Personal Care ◽  
Anaerobic Processes ◽  
Personal Care Product ◽  
Anaerobic Reactors ◽  
Treatment Technologies

Wastes from the personal care product (PCP) industry are often high in biodegradable carbon, which makes them amenable to aerobic biological treatment, although process costs are usually high due to aeration inefficiencies, high electricity demand and production of large amounts of sludge. As such, anaerobic treatment technologies are being considered to lower net energy costs by reducing air use and increasing methane production. To assess the amenability of PCP wastes to anaerobic treatment, methane yields and rates were quantified in different anaerobic reactors treating typical PCP wastes, including wastes from shampoo and hair colorant products. Overall, shampoo wastes were more amenable to methanogenesis with almost double the methane yields compared with colour wastes. To assess relevant microbial guilds, qPCR was performed on reactor biomass samples. Methanosaetaceae abundances were always significantly higher than Methanosarcinaceae and Methanomicrobiales abundances (P < 0.05), and did not differ significantly between waste types. Although colour wastes were less amenable to anaerobic treatment than shampoo wastes, differences cannot be explained by relative microbial abundances and probably result from the presence of inhibiting compounds in hair colorants (e.g., oxidants) at higher levels. Results showed that anaerobic technologies have great potential for treating PCP wastes, but additional work is needed to establish the basis of elevated methane yields and inhibition, especially when colorant wastes are present.

ASBR treatment of low strength industrial wastewater at psychrophilic temperatures

1997 ◽  
Vol 36 (2-3) ◽  
pp. 337-344 ◽  
Author(s):  
Gouranga C. Banik ◽  
Richard R. Dague
Keyword(s):  
Steady State ◽  
Industrial Wastewater ◽  
Anaerobic Treatment ◽  
Temperature Correction ◽  
Correction Coefficient ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Active Volume ◽  
Dry Milk ◽  
Steady State Performance

Anaerobic treatment of dilute wastewater was studied using three laboratory-scale anaerobic sequencing batch reactors (ASBR), each with an active volume of six (6) liters. The reactors were fed a synthetic substrate made from non-fat dry milk supplemented with nutrients and trace metals. The COD and BOD5 of the feed was 600 mg/l and 285 mg/l, respectively. Steady-state performance data were collected at reaction temperatures of 25, 20, 17.5, 15, 12.5, 10, 7.5 and 5°C over a period of two years. Hydraulic retention times (HRT) were maintained at 24, 16, 12, 8 and 6 hours. Results showed that the ASBR process was capable of achieving in excess of 90% soluble COD and BOD5 removal at temperatures of 25°C and 20°C at all HRTs. At the low temperature of 5°C and the six hour HRT, soluble COD and BOD5 removals were 62% and 75%, respectively. At the intermediate temperatures from 20°C down to 5°C and HRTs between 24 and 6 hours, removal of soluble organics ranged between 62 and 90 % for COD and 75 and 90 % for BOD5. In all cases, SRT were high enough to maintain good performance. Substrate utilization rates and half-velocity constants were also determined at all temperatures. The temperature correction coefficient was found to be 1.08 in the temperature range from 25°C to 7.5°C which follows the Q10 or Van't Hoff's rule.

Anaerobic Treatment of Synthetic Sulfate-Containing Wastewater under Thermophilic Conditions

1992 ◽  
Vol 25 (7) ◽  
pp. 193-202 ◽  
Author(s):  
A. Visser ◽  
Y. Gao ◽  
G. Lettinga
Keyword(s):  
Waste Water ◽  
Steady State ◽  
Methane Production ◽  
Anaerobic Treatment ◽  
Uasb Reactor ◽  
Methanogenic Activity ◽  
Sulfate Reducers ◽  
Activity Measurements ◽  
Thermophilic Conditions ◽  
Temperature Optima

The anaerobic treatment of a sulfate-containing waste water using a UASB reactor was studied at 55 °C. As substrate, acetate and a mixture of acetate, propionate and butyrate were used. With acetate as substrate it was shown that sulfate reducers are capable of using acetate as substrate at 55 °C, and that, under the conditions applied, they even outcompete acetoclastic methanogens. Batch-activity measurements with the sludge revealed temperature optima for acetate, propionate and butyrate degradation of ± 56-59, < 40 and 52-54 °C respectively. After switching the substrate to a mixture of acetate, propionate and butyrate, the reactor pH dropped from 8.3-8.6 to 7.6-7.9 and the methane production recovered. After the establishment of a pseudo-steady state situation the part of COD removed by methane production and sulfate reduction was ± 60 and 40 %. Results of batch activity experiments showed that the methanogenic activity dropped sharply at pH ≥ 8 and ≤ 6 causing a predominance of sulfate reducers at pH ≥ 8.

Temperature effect on the anaerobic treatment of potato-processing wastewater

1982 ◽  
Vol 9 (3) ◽  
pp. 549-557 ◽  
Author(s):  
K. C. Lin ◽  
R. C. Landine ◽  
S. Bliss
Keyword(s):  
Temperature Effect ◽  
Methane Production ◽  
Accumulation Rate ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Methane Content ◽  
Potato Processing ◽  
Potato Waste ◽  
Volumetric Rate ◽  
Anaerobic Lagoon

The performance of a laboratory-scale anaerobic lagoon–filter system treating unsettled potato-processing wastewater has been studied under controlled temperature conditions below 20 °C. The wastewater contained approximately 2700 mg/L of chemical oxygen demand (COD) and 1380 mg/L of suspended solids (SS). The system, buffered with lime, was fed continuously; detention times were 7.0 and 1.5 days for the lagoon and filter, respectively. The loading rate was 0.35 kg COD/(m3∙day) based on lagoon volume. There was 100% recycling but no sludge wastage.Between 20 and 10 °C, the system removed approximately 94% of the COD and 95% of SS. Down to 4 °C removals of 85% of COD and 93% of SS were obtained. At 2 °C system failure was imminent. Sludge accumulation rate was highest at 6 °C (0.41 g of SS accumulated per gram SS fed), four times the rate at 20 °C. Total methane production varied from 0.35 m3/kg COD removed at 20 °C down to 0.24 m3/kg COD removed at 4 °C, with a 62% decrease in volumetric rate. Methane content in the gas was 75–84%. The filter had a higher methane production-to-COD removal ratio and a higher methane content than the lagoon. Keywords: anaerobic lagoon, anaerobic filter, temperature effect, potato waste.

Quasi-steady-state performance of a heat pipe subjected to transient acceleration loadings

10.2514/3.895 ◽  
1997 ◽  
Vol 11 ◽  
pp. 306-309 ◽  
Author(s):  
Edwin H. Olmstead ◽  
Edward S. Taylor ◽  
Meng Wang ◽  
Parviz Moin ◽  
Scott K. Thomas ◽  
...  
Keyword(s):  
Steady State ◽  
Heat Pipe ◽  
Quasi Steady State ◽  
Steady State Performance

Vacuum Operation for Overloaded Anaerobic Treatment Systems

1989 ◽  
Vol 21 (4-5) ◽  
pp. 87-95
Author(s):  
J. De Santis ◽  
A. A. Friedman
Keyword(s):  
Volatile Fatty Acids ◽  
Loading Rate ◽  
Anaerobic Treatment ◽  
Optimum Operating ◽  
Operating Pressure ◽  
Simple Modification ◽  
Anaerobic Reactors ◽  
Fixed Film ◽  
Solids Retention ◽  
High Concentrations

Overloaded anaerobic treatment systems are characterized by high concentrations of volatile fatty acids and molecular hydrogen and poor conversion of primary substrates to methane. Previous experiments with fixed–film reactors indicated that operation with reduced headspace pressures enhanced anaerobic treatment. For these studies, four suspended culture, anaerobic reactors were operated with headspace pressures maintained between 0.5 and 1.0 atm and a solids retention time of 15 days. For lightly loaded systems (0.4 g SCOD/g VSS-day) vacuum operation provided minor treatment improvements. For shock organic loads, vacuum operation proved to be more stable and to support quicker recovery from upset conditions. Based on these studies and a companion set of bioassay tests, it was concluded that: (a) a loading rate of about 1.0 g SCOD/g VSS-day represents a practical loading limit for successful anaerobic treatment, (b) a headspace pressure of approximately 0.75 atm appears to be an optimum operating pressure for anaerobic systems and (c) simple modification to existing systems may provide relief for organically overloaded systems.

A Novel Control Scheme for PWM Boost Converter based on Sliding Mode Control using Particle Swarm Optimization

2020 ◽  
Vol 14 ◽  
Author(s):  
Gang Liu ◽  
Dong Qiu ◽  
Xiuru Wang ◽  
Ke Zhang ◽  
Huafeng Huang ◽  
...  
Keyword(s):  
Particle Swarm Optimization ◽  
Steady State ◽  
Sliding Mode ◽  
Particle Swarm ◽  
Mathematic Model ◽  
Absolute Error ◽  
Boost Converter ◽  
Sliding Mode Controller ◽  
Swarm Optimization ◽  
Steady State Performance

Background: The PWM Boost converter is a strongly nonlinear discrete system, especially when the input voltage or load varies widely, therefore, tuning the control parameters of which is a challenge work. Objective: In order to overcome the issues, particle swarm optimization (PSO) is employed for tuning the parameters of a sliding mode controller of a boost converter. Methods: Based on the analysis of the Boost converter model and its non-linear characteristics, a mathematic model of a boost converter with a sliding mode controller is built firstly. Then, the parameters of the Boost controller are adjusted based on the integrated time and absolute error (ITAE), integral square error (ISE) and integrated absolute error (IAE) indexes by PSO. Results: Simulation verification was performed, and the results show that the controllers tuned by the three indexes all have excellent robust stability. Conclusion: The controllers tuned by ITAE and ISE indexes have excellent steady-state performance, but the overshoot is large during the startup. The controller tuned by IAE index has better startup performance and slightly worse steady-state performance.

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