Combination of sonophotolysis and aerobic activated sludge processes for treatment of synthetic pharmaceutical wastewater.

The treatment ability and efficiency of sonophotolytic process, aerobic activated sludge (AS) process, and their combination in reduction of total organic carbon (TOC), total nitrogen (TN), chemical oxygen demand (COD), and biological oxygen demand (BOD) from a synthetic pharmaceutical wastewater (SPWW) were studied. Batch mode experiments were performed to obtain optimal experimental operating conditions for sonophotolysis process. Ultrasonic power of 140 W, initial pH solution of 2, and air flow rate of 3 L/min were found as optimum. The initial optimum molar ratio of H2O2/TOC was found to be 13.77 for sonophotolysis process alone in batch mode. In continuous mode, sonophotolysis was able to reduce TOC by 90% after 180 min retention time. Aerobic AS process alone after 48 h retention time reduced TOC by 67%. Combined sonophotolysis and aerobic AS processes improved the biodegradability of the SPWW and resulted in 98% TOC and 99% COD removal while decreasing the retention time in sonophotoreactor and aerobic AS reactor to 120 min and 24 h, respectively. Additionally, the consumption of H2O2 was reduced significantly in the combined processes.

Validation of On-line Respiration Meter and its Applications by Computer Simulation

10.2166/wst.1992.0578 ◽

1992 ◽

Vol 26 (5-6) ◽

pp. 1355-1363 ◽

Cited By ~ 2

Author(s):

C-W. Kim ◽

H. Spanjers ◽

A. Klapwijk

Keyword(s):

Steady State ◽

Activated Sludge ◽

Respiration Rate ◽

Oxygen Demand ◽

Operating Conditions ◽

Mass Balances ◽

Short Term ◽

Respiration Rates ◽

On Line ◽

Made In

An on-line respiration meter is presented to monitor three types of respiration rates of activated sludge and to calculate effluent and influent short term biochemical oxygen demand (BODst) in the continuous activated sludge process. This work is to verify if the calculated BODst is reliable and the assumptions made in the course of developing the proposed procedure were acceptable. A mathematical model and a dynamic simulation program are written for an activated sludge model plant along with the respiration meter based on mass balances of BODst and DO. The simulation results show that the three types of respiration rate reach steady state within 15 minutes under reasonable operating conditions. As long as the respiration rate reaches steady state the proposed procedure calculates the respiration rate that is equal to the simulated. Under constant and dynamic BODst loading, the proposed procedure is capable of calculating the effluent and influent BODst with reasonable accuracy.

Cost Effective Method for Toxicity Screening of Pharmaceutical Wastewater Containing Inorganic Salts and Harmful Organic Compounds

Environmental and Climate Technologies ◽

10.2478/rtuect-2019-0004 ◽

2019 ◽

Vol 23 (1) ◽

pp. 52-63 ◽

Cited By ~ 2

Author(s):

Elina Strade ◽

Daina Kalnina

Keyword(s):

Activated Sludge ◽

Biological Treatment ◽

Oxygen Demand ◽

Cost Effective ◽

Practical Implementation ◽

Toxicity Screening ◽

Pharmaceutical Wastewater ◽

Cost Effective Method ◽

Wide Range ◽

Wastewater Biological Treatment

Abstract Pharmaceutical wastewater biological treatment plants are stressed with multi-component wastewater and unexpected variations in wastewater flow, composition and toxicity. To avoid operational problems and reduced wastewater treatment efficiency, accurate monitoring of influent toxicity on activated sludge microorganisms is essential. This paper outlines how to predict highly toxic streams, which should be avoided, using measurements of biochemical oxygen demand (BOD), if they are made in a wide range of initial concentration. The results indicated that wastewater containing multivalent Al3+ cations showed a strong toxic effect on activated sludge biocenosis irrespectively of dilutions, while toxicity of phenol and formaldehyde containing wastewater decreased considerably with increasing dilution. Activated sludge microorganisms were not sensitive to wastewater containing halogenated sodium salts (NaCl, NaF) and showed high treatment capacity of saline wastewater. Our findings confirm that combined indicators of contamination, such as chemical oxygen demand (COD), alone do not allow evaluating potential toxic influence of wastewater. Obtained results allow identifying key inhibitory substances in pharmaceutical wastewater and evaluating potential impact of new wastewater streams or increased loading on biological treatment system. Proposed method is sensitive and cost effective and has potential for practical implementation in multiproduct pharmaceutical wastewater biological treatment plants.

Fine Bubble Aeration Using a High Density Diffuser System

10.2166/wst.1992.0756 ◽

1992 ◽

Vol 26 (9-11) ◽

pp. 2437-2440 ◽

Cited By ~ 1

Author(s):

K. Thatcher

Keyword(s):

Activated Sludge ◽

Oxygen Transfer ◽

Oxygen Demand ◽

High Density ◽

Plant Performance ◽

Energy Usage ◽

High Quality ◽

Transfer Rates ◽

Fine Bubble ◽

Current developments with the activated sludge processes with highly concentrated effluents highlight the requirement to (a) reduce energy usage (b) promote the production of high quality effluent. Having observed the efforts being made to improve plant performance we became aware that current methods had to be improved. It was also noted that a period of stagnation had occurred in the development of effective aeration systems. Improved aeration methods are needed which would allow for oxygen transfer efficiencies to be greater than 2kg/kWh. Such oxygen transfer rates should be continually variable in line with the oxygen demand prevailing at any given time. In our study of activated sludge plants we found that operational and electrical/mechanical maintenance was proving to be time consuming and very costly. With these problems in mind we have designed and developed the Fine Bubble High Density Diffuser System.

Use of microtox tests for screening industrial wastewater toxicity

10.2166/wst.1996.0237 ◽

1996 ◽

Vol 34 (10) ◽

pp. 43-50 ◽

Cited By ~ 7

Author(s):

Oliver J. Hao ◽

Shin Chien-Jen ◽

Lin Cheng-Fang ◽

Jeng Fu-Tien ◽

Chen Zen-Chyuan

Keyword(s):

Activated Sludge ◽

Oxygen Demand ◽

Industrial Wastes ◽

Wastewater Management ◽

Waste Discharge ◽

Significant Toxicity ◽

Microtox Toxicity ◽

Microtox Test ◽

Activated Sludge Processes ◽

The Impact

Conventional parameters such as chemical oxygen demand and suspended solids may not detect toxic compounds present in a variety of industrial wastewaters and treated wastes. Thus, the presence of toxicity in many industrial wastes presents a significant impact on biological wastewater treatment, and exerts adverse effects on receiving waters. Because of their easy technique and rapid turnaround results, the Microtox tests were used in this study to pinpoint unusual wastewaters, evaluate the toxicity reduction through activated sludge processes, observe the impact of excessive chemical addition to meet the transparency standard, and measure the impact of waste discharge on one particular receiving water. It was found that the results of Microtox tests were useful for such purposes; i.e., low COD wastes exhibited high Microtox toxicity; some activated sludge processes removed significant toxicity; and some effluents from coagulation/oxidation processes showed an increased toxicity. The application of the Microtox test to wastewater management is discussed.

Volatile Fatty Acids and Biomethane Recovery from Thickened Waste Activated Sludge: Hydrothermal Pretreatment’s Retention Time Impact

Processes ◽

10.3390/pr8121580 ◽

2020 ◽

Vol 8 (12) ◽

pp. 1580

Author(s):

Farokh laqa Kakar ◽

Ahmed El Sayed ◽

Neha Purohit ◽

Elsayed Elbeshbishy

Keyword(s):

Fatty Acids ◽

Activated Sludge ◽

Retention Time ◽

Volatile Fatty Acids ◽

Oxygen Demand ◽

Hydrothermal Pretreatment ◽

Waste Activated Sludge ◽

Optimum Conditions ◽

Pretreatment Temperature ◽

Biomethane Production

The main objective of this study was to evaluate the hydrothermal pretreatment’s retention time influence on the volatile fatty acids and biomethane production from thickened waste activated sludge under mesophilic conditions. Six different retention times of 10, 20, 30, 40, 50, and 60 min were investigated while the hydrothermal pretreatment temperature was kept at 170 °C. The results showed that the chemical oxygen demand (COD) solubilization increased by increasing the hydrothermal pretreatment retention time up to 30 min and stabilized afterwards. The highest COD solubilization of 48% was observed for the sample pretreated at 170 °C for 30 min. Similarly, the sample pretreated at 170 °C for 30 min demonstrated the highest volatile fatty acids yield of 14.5 g COD/Lsubstrate added and a methane yield of 225 mL CH4/g TCODadded compared to 4.3 g COD/Lsubstrate added and 163 mL CH4/g TCODadded for the raw sample, respectively. The outcome of this study revealed that the optimum conditions for solubilization are not necessarily associated with the best fermentation and/or digestion performance.

Trade-off between carbon emission and effluent quality of activated sludge processes under seasonal variations of wastewater temperature and mean cell retention time

The Science of The Total Environment ◽

10.1016/j.scitotenv.2015.12.102 ◽

2016 ◽

Vol 547 ◽

pp. 331-344 ◽

Cited By ~ 9

Author(s):

Jingbo Guo ◽

Xin Fu ◽

G. Andrés Baquero ◽

Reza Sobhani ◽

Daniel A. Nolasco ◽

...

Keyword(s):

Activated Sludge ◽

Retention Time ◽

Seasonal Variations ◽

Carbon Emission ◽

Cell Retention ◽

Trade Off ◽

Effluent Quality ◽

Modelling and simulation of the steady-state of secondary settlers in wastewater treatment plants

10.2166/wst.2001.0384 ◽

2001 ◽

Vol 43 (7) ◽

pp. 39-46 ◽

Cited By ~ 12

Author(s):

I. Queinnec ◽

D. Dochain

Keyword(s):

Fluid Dynamics ◽

Computational Fluid Dynamics ◽

Wastewater Treatment ◽

Steady State ◽

Activated Sludge ◽

Parameter Identification ◽

Wastewater Treatment Plants ◽

Operating Conditions ◽

Sensitivity Studies ◽

This paper discusses the steady-state modelling of thickening in circular secondary settlers of activated sludge processes. The limitations of the solid flux theory basic models to represent steady-state operating conditions serve as a basis to introduce more sophisticated models derived from computational fluid dynamics. Parameter identification and sensitivity studies have been performed from lab-scale continuous experiments.

Population Dynamics of Bacteria for Phosphorus Removal in Sequencing Batch Reactor (SBR) Activated Sludge Processes

10.2166/wst.1991.0526 ◽

1991 ◽

Vol 23 (4-6) ◽

pp. 755-763 ◽

Cited By ~ 5

Author(s):

M. Okada ◽

A. Murakami ◽

C. K. Lin ◽

Y. Ueno ◽

T. Okubo

Keyword(s):

Activated Sludge ◽

Retention Time ◽

Growth Rates ◽

Sodium Acetate ◽

Sequencing Batch Reactor ◽

Specific Growth ◽

Batch Reactor ◽

Organic Substrates ◽

Specific Growth Rates ◽

Laboratory-scale sequencing batch reactor (SBR) activated sludge processes were operated using synthetic wastewater to clarify the effects of sludge retention time(SRT) and organic substrates on the accumulation of bio-P-bacteria. The accumulation of bio-P-bacteria could be enhanced by wide variation in concentration of organic substrates by giving a short fill period and sufficient anaerobic conditions. However, the accumulation could not be enhanced in the reactor operated with SRT less than 25 d in spite of the higher, more than 0.1 d−1, specific growth rates observed in the isolated strains of bio-P-bacteria. The specific growth rates of bio-P-bacteria were estimated at 0.040 d−1, 0.030 d−1 and 0.035 d−1 in the SBR activated sludge processes fed with sodium acetate (A), glucose and polypeptone (GP) and polypeptone (P), respectively. Therefore, a large sludge retention time would be necessary for the accumulation of bio-P-bacteria. Volatile fatty acids (VFA), such as sodium acetate (A), seemed to be more effective than other organic substrates (GP and P) for the accumulation of bio-P-bacteria in activated sludge ecosystems.

Influences of wastewater composition and operating conditions on activated sludge bulking and scum formation

10.2166/wst.1994.0558 ◽

1994 ◽

Vol 30 (11) ◽

pp. 181-189 ◽

Cited By ~ 8

Author(s):

Jürg Kappeler ◽

Willi Gujer

Keyword(s):

Activated Sludge ◽

Retention Time ◽

Mass Fraction ◽

Oxygen Supply ◽

Reactor Design ◽

Operating Conditions ◽

Reactor Configuration ◽

Growth Requirements ◽

Filamentous Microorganisms ◽

Solids Retention

Bulking and scum formation (scumming) are common phenomena in activated sludge plants. Four main problem groups with filamentous microorganisms with different growth requirements are distinguished: (1) “Aerobic Bulking”, (2) “Scumming due to Actinomycetes”, (3) “Low F/M Bulking and Scumming” and (4) “Bulking due to Sulphide Oxidising Bacteria”. Various wastewater fractions, such as readily biodegradable substrate, surfactants, hydrophilic and lipophilic slowly-biodegradable substrate, inoculated filamentous microorganisms and sulphide, strongly influence the biocenosis composition. Apart from wastewater composition, operating conditions, such as solids retention time, reactor configuration, mechanical stress by recirculation pumps and insufficient oxygen supply, are often decisive for the occurrence of a bulking or scumming problem, as well. A predictive scheme for the possible occurrence of the four main problem groups is presented for different combinations of wastewater compositions, operating conditions and reactor design. All four problem groups can occur in aerobic nitrifying systems. In non-nitrifying systems, only “Aerobic Bulking” and “Bulking due to Sulphide Oxidising Bacteria” are expected, depending on wastewater composition and operating conditions. In systems with a large anoxic mass fraction, “Low F/M Bulking and Scumming” is typically the only problem group. Since wastewater fractions can hardly be manipulated in practice, at least operating conditions and reactor design should be optimised in order to obtain a better performance of the plants.