Using excess sludge as carbon source for enhanced nitrogen removal and sludge reduction with hydrolysis technology

2010 ◽  
Vol 62 (7) ◽  
pp. 1536-1543 ◽  
Author(s):  
Yong-Qing Gao ◽  
Yong-Zhen Peng ◽  
Jing-Yu Zhang ◽  
Jian-Long Wang ◽  
Liu Ye
Keyword(s):  
Carbon Source ◽  
Nitrogen Removal ◽  
Wastewater Treatment Plants ◽  
Reduction Rate ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Batch Reactors ◽  
Sludge Reduction ◽  
Zero Order Kinetics ◽  
Soluble Chemical Oxygen Demand

In order to improve the nitrogen removal efficiency and to achieve the sludge reduction in traditional wastewater treatment plants, a combined hydrolysis-anoxic-oxic (H-A-O) pilot-scaled reactor was used in this study to investigate the possibility and validity of using excess activated sludge (EAS) fermentation liquids to enhance the nitrogen removal. The results clearly showed that sludge acidification rate in fermentation reactor can reach to 43.2%. The percentages of acetic acid, propionic acid and butyric acid in the fermentation liquids were 68.4, 25.3 and 6.3%, respectively, while those in domestic wastewater were 73.0, 12.2 and 13.8%, respectively. Bioavailability of soluble chemical oxygen demand (SCOD) from fermentation liquids and domestic wastewater were investigated in batch reactors with nitrate as the electron accepter as well. The corresponding specific denitrification rates were 0.15 g NO3−-N/g VSS d−1 and 0.09 g NO3−-N/g VSS d−1. When the substances were enough, the denitrification reaction appeared to follow the zero-order kinetics. The results also showed that, when the H-A-O pilot-scaled reactor was operated continuously and sludge fermentation liquids were applied as additional carbon source in the A-O reactor, the removal efficiencies of SCOD, NH4+-N and total nitrogen (TN) were higher than 90, 95 and 79%, respectively. EAS reduction rate in this system was able to reach 40.4%, and the sludge VSS/SS ratio decreased from 0.82 to 0.59 after hydrolysis step.

scholarly journals Efficiency and Technological Reliability of Contaminant Removal in Household WWTPs with Activated Sludge

2021 ◽  
Vol 11 (4) ◽  
pp. 1889 ◽  
Author(s):  
Agnieszka Micek ◽  
Krzysztof Jóźwiakowski ◽  
Michał Marzec ◽  
Agnieszka Listosz ◽  
Tadeusz Grabowski
Keyword(s):  
Activated Sludge ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Pollutant Removal ◽  
Treated Wastewater ◽  
Contaminant Removal ◽  
Nitrogen And Phosphorus ◽  
Wastewater Samples ◽  
Polish Law

The results of research on the efficiency and technological reliability of domestic wastewater purification in two household wastewater treatment plants (WWTPs) with activated sludge are presented in this paper. The studied facilities were located in the territory of the Roztocze National Park (Poland). The mean wastewater flow rate in the WWTPs was 1.0 and 1.6 m3/day. In 2017–2019, 20 series of analyses were done, and 40 wastewater samples were taken. On the basis of the received results, the efficiency of basic pollutant removal was determined. The technological reliability of the tested facilities was specified using the Weibull method. The average removal efficiencies for the biochemical oxygen demand in 5 days (BOD5) and chemical oxygen demand (COD) were 66–83% and 62–65%, respectively. Much lower effects were obtained for total suspended solids (TSS) and amounted to 17–48%, while the efficiency of total phosphorus (TP) and total nitrogen (TN) removal did not exceed 34%. The analyzed systems were characterized by the reliability of TSS, BOD5, and COD removal at the level of 76–96%. However, the reliability of TN and TP elimination was less than 5%. Thus, in the case of biogenic compounds, the analyzed systems did not guarantee that the quality of treated wastewater would meet the requirements of the Polish law during any period of operation. This disqualifies the discussed technological solution in terms of its wide application in protected areas and near lakes, where the requirements for nitrogen and phosphorus removal are high.

Conditions and technologies of biological wastewater treatment in Hungary

2012 ◽  
Vol 65 (9) ◽  
pp. 1676-1683 ◽  
Author(s):  
G. M. Tardy ◽  
V. Bakos ◽  
A. Jobbágy
Keyword(s):  
Wastewater Treatment ◽  
Carbon Source ◽  
Nitrogen Removal ◽  
Wastewater Treatment Plants ◽  
Treatment Temperature ◽  
Low Carbon ◽  
Biological Phosphorus Removal ◽  
Wastewater Quality ◽  
Removal Technologies ◽  
Biological Nitrogen

A survey has been carried out involving 55 Hungarian wastewater treatment plants in order to evaluate the wastewater quality, the applied technologies and the resultant problems. Characteristically the treatment temperature is very wide-ranging from less than 10 °C to higher than 26 °C. Influent quality proved to be very variable regarding both the organic matter (typical COD concentration range 600–1,200 mg l−1) and the nitrogen content (typical NH4-N concentration range 40–80 mg l−1). As a consequence, significant differences have been found in the carbon availability for denitrification from site to site. Forty two percent of the influents proved to lack an appropriate carbon source. As a consequence of carbon deficiency as well as technologies designed and/or operated with non-efficient denitrification, rising sludge in the secondary clarifiers typically occurs especially in summer. In case studies, application of intermittent aeration, low DO reactors, biofilters and anammox processes have been evaluated, as different biological nitrogen removal technologies. With low carbon source availability, favoring denitrification over enhanced biological phosphorus removal has led to an improved nitrogen removal.

Characterization of slowly-biodegradable organic compounds and hydrolysis kinetics in tropical wastewater for biological nitrogen removal

2020 ◽  
Vol 81 (1) ◽  
pp. 71-80 ◽  
Author(s):  
Seow Wah How ◽  
Jia Huey Sin ◽  
Sharon Ying Ying Wong ◽  
Pek Boon Lim ◽  
Alijah Mohd Aris ◽  
...  
Keyword(s):  
Nitrogen Removal ◽  
Uptake Rate ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Hydrolysis Rate ◽  
Biological Nitrogen Removal ◽  
Tropical Region ◽  
Kinetic Coefficients ◽  
Wastewater Samples ◽  
Biological Nitrogen

Abstract Many developing countries, mostly situated in the tropical region, have incorporated a biological nitrogen removal process into their wastewater treatment plants (WWTPs). Existing wastewater characteristic data suggested that the soluble chemical oxygen demand (COD) in tropical wastewater is not sufficient for denitrification. Warm wastewater temperature (30 °C) in the tropical region may accelerate the hydrolysis of particulate settleable solids (PSS) to provide slowly-biodegradable COD (sbCOD) for denitrification. This study aimed to characterize the different fractions of COD in several sources of low COD-to-nitrogen (COD/N) tropical wastewater. We characterized the wastewater samples from six WWTPs in Malaysia for 22 months. We determined the fractions of COD in the wastewater by nitrate uptake rate experiments. The PSS hydrolysis kinetic coefficients were determined at tropical temperature using an oxygen uptake rate experiment. The wastewater samples were low in readily-biodegradable COD (rbCOD), which made up 3–40% of total COD (TCOD). Most of the biodegradable organics were in the form of sbCOD (15–60% of TCOD), which was sufficient for complete denitrification. The PSS hydrolysis rate was two times higher than that at 20 °C. The high PSS hydrolysis rate may provide sufficient sbCOD to achieve effective biological nitrogen removal at WWTPs in the tropical region.

Two-stage entrapped mixed microbial cell process for simultaneous removal of organics and nitrogen for rural domestic sewage application

2004 ◽  
Vol 49 (5-6) ◽  
pp. 281-288 ◽  
Author(s):  
S.J. Kim ◽  
P.Y. Yang
Keyword(s):  
Removal Efficiency ◽  
Loading Rate ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Microbial Cell ◽  
Two Stage ◽  
Rate Limiting Step ◽  
Soluble Chemical Oxygen Demand ◽  
Removal Efficiencies ◽  
Entrapped Mixed Microbial Cell

A two-stage entrapped mixed microbial cell (2SEMMC) process which separates nitrification and denitrification phases by the installation of the anoxic and oxic EMMC reactors packed with EMMC carriers was operated with 6, 4, 3, and 2 hours of hydraulic retention time (HRT) using simulated domestic wastewater. The activated sludge was immobilized using cellulose acetate for the EMMC carriers. Similar soluble chemical oxygen demand (SCOD) removal efficiencies of 90-97% were observed for all HRTs (SCOD loading rate of 0.84-2.30 g/L/d) applied. In order to achieve more than 80 % of TN removal efficiency, the HRT should be maintained higher than 4 hours (less than 0.24 g/L/d of TN loading rate). Denitrification was a rate-limiting step which controlled overall TN removal efficiency at TN loading rate of 0.15-0.31 g/L/d although nitrification efficiencies achieved 97-99 %. The effluent TSS of less than 25 mg/L in the 2SEMMC process was maintained at the SCOD loading rate of less than 1.23 g/L/d with back-washing intervals of 5 and 10 days in the anoxic and oxic EMMC reactors, respectively. The minimum HRT of 4 hours is required for high removal efficiencies of organics (average 95.6 %) and nitrogen (average 80.5 %) in the 2SEMMC process with 3 times of recirculation ratio.

scholarly journals Enhanced Nitrogen Removal from Domestic Wastewater by Partial-Denitrification/Anammox in an Anoxic/Oxic Biofilm Reactor

Processes ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 109
Author(s):  
Yu Huang ◽  
Yongzhen Peng ◽  
Donghui Huang ◽  
Jiarui Fan ◽  
Rui Du
Keyword(s):  
Nitrogen Removal ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Biofilm Reactor ◽  
Anammox Bacteria ◽  
Stable Operation ◽  
Ammonium Oxidation ◽  
N Accumulation ◽  
Carbon Demand ◽  
Oxidation Efficiency

A partial-denitrification coupling with anaerobic ammonium oxidation (anammox) process (PD/A) in a continuous-flow anoxic/oxic (A/O) biofilm reactor was developed to treat carbon-limited domestic wastewater (ammonia (NH4+-N) of 55 mg/L and chemical oxygen demand (COD) of 148 mg/L in average) for about 200 days operation. Satisfactory NH4+-N oxidation efficiency above 95% was achieved with rapid biofilm formation in the aerobic zone. Notably, nitrite (NO2−-N) accumulation was observed in the anoxic zone, mainly due to the insufficient electron donor for complete nitrate (NO3−-N) reduction. The nitrate-to-nitrite transformation ratio (NTR) achieved was as high as 64.4%. After the inoculation of anammox-enriched sludge to anoxic zones, total nitrogen (TN) removal was significantly improved from 37.3% to 78.0%. Anammox bacteria were effectively retained in anoxic biofilm utilizing NO2−-N produced via the PD approach and NH4+-N in domestic wastewater, with the relative abundance of 5.83% for stable operation. Anammox pathway contributed to TN removal by a high level of 38%. Overall, this study provided a promising method for mainstream nitrogen removal with low energy consumption and organic carbon demand.

scholarly journals Effect of digester F/M ratio on gas production and sludge minimization of ultrasonically treated sludge

2010 ◽  
Vol 62 (7) ◽  
pp. 1510-1517 ◽  
Author(s):  
Gözde T. Köksoy ◽  
F. Dilek Sanin
Keyword(s):  
Oxygen Demand ◽  
Gas Production ◽  
Batch Reactors ◽  
Thermal Methods ◽  
Anaerobic Digesters ◽  
Sludge Pretreatment ◽  
Sludge Minimization ◽  
Effect Of Food ◽  
Soluble Chemical Oxygen Demand ◽  
Sonication Parameters

Sludge pretreatment by mechanical, chemical or thermal methods before anaerobic digestion has been applied to increase the digestability of excess sludge. Pretreatment processes rely on their ability to disrupt cell membranes and to release organic materials from the cells into the aqueous phase. Pretreatment by mechanical disintegration has grown rapidly in recent years in parallel with the advances in technology. Ultrasonic sludge disintegration –one of the most commonly used mechanical pretreatment methods- enables the occurrence of cavitation bubbles for the break-up of microorganism cells to extract intracellular materials. The purpose of this study was to conduct disintegration experiments to optimize sonication parameters and to operate subsequent batch anaerobic digesters to examine the effect of food to microorganism ratio (F/M) in sonicated and unsonicated samples. Results showed that high sonication powers and longer treatment times were effective in sludge disintegration in terms of soluble chemical oxygen demand release. Sonicated sludge digested in batch reactors with higher initial F/M ratio caused higher methane generations, higher sludge reductions and had better dewatering characteristics.

The effects of external carbon loading on nitrogen removal in sequencing batch reactors

1994 ◽  
Vol 30 (6) ◽  
pp. 73-81 ◽  
Author(s):  
N. F. Y. Tam ◽  
G. L. W. Leung ◽  
Y. S. Wong
Keyword(s):  
Nitrogen Removal ◽  
Sodium Acetate ◽  
Batch Reactor ◽  
Carbon Sources ◽  
Domestic Wastewater ◽  
Nitrate Content ◽  
Carbon Substrate ◽  
High Dose ◽  
Batch Reactors ◽  
Sodium Propionate

A bench-scale study was undertaken to examine the effects of easily biodegradable organic carbon substrate on denitrification reaction and overall nitrogen removal from domestic wastewater under a modified sequencing batch reactor (SBR) system. The operation strategy of the SBR consisted of 0.75 h FILL, 8 h REACT separated into 4 h aerobic, 3 h anoxic and 1 h aerobic stages, 1.5 h SETTLE, 1 h DRAW and 0.75 h IDLE. Methanol, sodium acetate and sodium propionate, at the concentrations equivalent to theoretical COD values of 50, 100 and 150 mg O2 1−1 were used as the external carbon sources and added to the reactors prior to the anoxic stage. The study reveals that 4 h aerobic stage was sufficient to nitrify more than 98% NH4+-N and carbon addition caused slightly more nitrification than the control. Addition of sodium propionate at a low concentration (50 mg O2 1−1) significantly enhanced the denitrification process, the nitrate content in this reactor dropped to 3 mg 1−1 (89% reduction) at the end of the anoxic stage. Among the three substrate added at low dose, sodium propionate was the most effective carbon source, followed by acetate and the least effective one was methanol. When the carbon substrate were added at the doses of 100 and 150 mg O2 1−1, the denitrification rates of the acetate reactors recorded at the first hour of the anoxic stage were similar to those of the propionate's and significantly higher than the methanol reactors. When high dose (150 mg O2 1−1) of acetate or propionate was used, 95% reduction in wastewater NOx-N was found after 1 h anoxic stage while 3 h anoxic stage was required when the carbon dose was at 100 mg O2 1−1, indicating that addition of external carbon substrate at large quantity could shorten the denitrification time. However, the final effluent discharged from reactors treated with high dose of acetate and propionate contained more than 20 mg 1−1 BOD5 which might cause a contamination problem. Therefore, addition of sodium acetate or propionate at the concentration equivalent to theoretical COD values of 100 mg O2 1−1 appeared to be the most economical and reliable option.

scholarly journals Multivariate analysis of activated sludge community in full-scale wastewater treatment plants

2020 ◽  
Vol 28 (3) ◽  
pp. 3579-3589
Author(s):  
Mateusz Sobczyk ◽  
Agnieszka Pajdak-Stós ◽  
Edyta Fiałkowska ◽  
Łukasz Sobczyk ◽  
Janusz Fyda
Keyword(s):  
Multivariate Analysis ◽  
Wastewater Treatment ◽  
Activated Sludge ◽  
Community Composition ◽  
Process Parameters ◽  
Wastewater Treatment Plants ◽  
Reduction Rate ◽  
Oxygen Demand ◽  
Principal Component ◽  
Composition Process

AbstractWe investigated changes in protozoa and metazoa community in relation to process parameters in activated sludge from four wastewater treatment plants (WWTPs) throughout the period of 1 year. Principal component analysis (PCA) showed that activated sludge from investigated treatment plants had different dominating species representatives and community composition mainly depends on individual features of the treatment plants. Redundancy analysis (RDA) showed that the temperature in bioreactors was the most relevant factor explaining changes in the microorganism community, whereas reduction rate of chemical oxygen demand (COD), biological oxygen demand (BOD5), suspended solids (SS), and total nitrogen (TN) did not sufficiently explain the variation in protozoa and metazoan community composition. The results indicate that in stable working WWTP it is difficult to find a pronounced link between activated sludge species composition, process parameters, and plant configuration. Applied multivariate analysis can be a valuable tool for the exploration of the relations between community composition and WWTP process parameters.

Tech-IA floating system introduced in urban wastewater treatment plants in the Veneto region – Italy

2013 ◽  
Vol 68 (5) ◽  
pp. 1144-1150 ◽  
Author(s):  
Anna Mietto ◽  
Maurizio Borin ◽  
Michela Salvato ◽  
Paolo Ronco ◽  
Nicola Tadiello
Keyword(s):  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Alnus Glutinosa ◽  
Primary Treatment ◽  
Ammonia Nitrogen ◽  
Surface Flow ◽  
Treatment Wetland ◽  
N Removal ◽  
Floating System

The performance of three integrated wetland treatment plants (horizontal sub-surface flow (h-SSF) and floating treatment wetland (FTW) with differentiated primary treatments) designed for treating domestic wastewater was investigated, monitoring total (TN), nitrate (NO3-N), nitrite (NO2-N) and ammonia nitrogen (NH4-N), total (TP) and phosphate phosphorus (PO4-P), chemical (COD) and biological oxygen demand (BOD5), and dissolved oxygen (DO) at the inlet and outlet of each wetland section from February 2011 to June 2012. Sediments settled in the FTW were collected and analyzed. The growth of plants in each system was also monitored, observing their general conditions. The chemical–physical characteristics of the pretreated domestic wastewater depended on the primary treatment installed. During the monitoring period we observed different reduction performance of the wetland sector in the three sites. In general, the wetland systems demonstrated the capacity to reduce TN, COD, BOD5 and Escherichia coli, whereas NO3-N and NH4-N removal was strictly influenced by the chemical conditions, in particular DO concentration, in the h-SSF and FTW. Vegetation (Phragmites australis, Alnus glutinosa and Salix eleagnos) was well established in the h-SSF as well as in the floating elements (Iris pseudacorus), although there were some signs of predation. FTW is a relatively novel wetland system, so the results obtained from this study can pave the way for the application of this technology.

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