Evaluating the excess sludge reduction in activated sludge system with ultrasonic treatment

2018 ◽  
Vol 77 (9) ◽  
pp. 2341-2347 ◽  
Author(s):  
Shuang Wu ◽  
Min Zheng ◽  
Qian Dong ◽  
Yanchen Liu ◽  
Chengwen Wang
Keyword(s):  
Activated Sludge ◽  
Ultrasonic Treatment ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Sludge Reduction ◽  
Treatment Technology ◽  
Ph Variation ◽  
Monod Equation ◽  
Soluble Chemical Oxygen Demand ◽  
Excess Sludge Reduction

Abstract Ultrasonic treatment for enhancing biological processes has recently attracted considerable attention in wastewater treatment. In this study, we systematically investigated the mixed liquor properties of activated sludge under ultrasonic treatment. The sludge samples were collected from the aerobic tank of a full-scale membrane bioreactor (MBR) treating municipal wastewater, and the volatile suspended solids (VSS) concentration was approximately 6.0 g/L. The results showed that ultrasonic treatment induced floc disintegration, organics release, temperature increase, microbial activity and pH variation. The maximum mg soluble chemical oxygen demand (COD) per mg VSS released was estimated to be 0.147 using the Monod equation. The exponential increase in the concentration of dissolved organic matter is related to the loss of relative heterotrophic bacterial activity. A sonolysis-cryptic growth model was demonstrated to be capable of describing ultrasonic sludge reduction, which would support the further development of ultrasonic treatment technology in activated sludge systems.

Anaerobic co-digestion of winery waste and waste activated sludge: assessment of process feasibility

2013 ◽  
Vol 69 (2) ◽  
pp. 269-277 ◽  
Author(s):  
C. Da Ros ◽  
C. Cavinato ◽  
F. Cecchi ◽  
D. Bolzonella
Keyword(s):  
Activated Sludge ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Waste Activated Sludge ◽  
Organic Loading ◽  
Operational Conditions ◽  
Loading Rates ◽  
Thermophilic Conditions ◽  
Soluble Chemical Oxygen Demand

In this study the anaerobic co-digestion of wine lees together with waste activated sludge in mesophilic and thermophilic conditions was tested at pilot scale. Three organic loading rates (OLRs 2.8, 3.3 and 4.5 kgCOD/m3d) and hydraulic retention times (HRTs 21, 19 and 16 days) were applied to the reactors, in order to evaluate the best operational conditions for the maximization of the biogas yields. The addition of lee to sludge determined a higher biogas production: the best yield obtained was 0.40 Nm3biogas/kgCODfed. Because of the high presence of soluble chemical oxygen demand (COD) and polyphenols in wine lees, the best results in terms of yields and process stability were obtained when applying the lowest of the three organic loading rates tested together with mesophilic conditions.

scholarly journals Improving and upgrading an existing activated sludge with a compact MBBR – disc filters parallel line for municipal wastewater treatment in touristic alpine areas

2020 ◽  
Vol 15 (2) ◽  
pp. 515-527
Author(s):  
L. Desa ◽  
P. Kängsepp ◽  
L. Quadri ◽  
G. Bellotti ◽  
K. Sørensen ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Wastewater Treatment Plants ◽  
Oxygen Demand ◽  
Parallel Line ◽  
Ammonium Nitrogen ◽  
Biofilm Reactor ◽  
Municipal Wastewater Treatment ◽  
Yearly Average

Abstract Many wastewater treatment plants (WWTP) in touristic areas struggle to achieve the effluent requirements due to seasonal variations in population. In alpine areas, the climate also determines a low wastewater temperature, which implies long sludge retention time (SRT) needed for the growth of nitrifying biomass in conventional activated sludge (CAS). Moreover, combined sewers generate high flow and dilution. The present study shows how the treatment efficiency of an existing CAS plant with tertiary treatment can be upgraded by adding a compact line in parallel, consisting of a Moving Bed Biofilm Reactor (MBBR)-coagulation-flocculation-disc filtration. This allows the treatment of influent variations in the MBBR and a constant flow supply to the activated sludge. The performance of the new 2-step process was comparable to that of the improved existing one. Regardless significant variations in flow (10,000–25,000 m3/d) and total suspended solids (TSS) (50–300 mg/L after primary treatment) the effluent quality fulfilled the discharge requirements. Based on yearly average effluent data, TSS were 11 mg/L, chemical oxygen demand (COD) 27 mg/L and total phosphorus (TP) 0.8 mg/L. After the upgrade, ammonium nitrogen (NH4-N) dropped from 4.9 mg/L to 1.3 mg/L and the chemical consumption for phosphorus removal was reduced.

scholarly journals The effects of a full-scale anaerobic side-stream reactor on sludge decay and biomass activity

2019 ◽  
Vol 79 (6) ◽  
pp. 1081-1091 ◽  
Author(s):  
V. F. Velho ◽  
G. Andreottola ◽  
P. Foladori ◽  
R. H. R. Costa
Keyword(s):  
Activated Sludge ◽  
Mass Balance ◽  
Oxygen Demand ◽  
Full Scale ◽  
Sludge Reduction ◽  
Solid Mass ◽  
Anaerobic Conditions ◽  
Side Stream ◽  
Biomass Activity ◽  
Heterotrophic Biomass

Abstract A full-scale anaerobic side-stream reactor (ASSR) for sludge reduction was monitored in terms of sludge production and compared with the previous conventional activated sludge configuration (CAS). A detailed solid mass balance was calculated on the whole full-scale plant to estimate the sludge reduction associated with the ASSR. The activity of the biomass, which undergoes alternation of aerobic and anaerobic conditions, was investigated by the respirometric test. The ASSR promoted a reduction of heterotrophic biomass activity and the substrate consumption rate in the activated sludge implemented with ASSR (AS + ASSR) was 36% smaller than in the CAS period. The solid mass balance indicated a sludge reduction of 28%. During the 270-day operation, the observed sludge yield passed from 0.438 kgTSS/kgCOD in the CAS to 0.315 in the AS + ASSR configuration. The solubilization of chemical oxygen demand (COD), NH4+-N and orthophosphate were verified under anaerobic conditions. The results suggest that the possible mechanisms of sludge reduction were the increase of the system sludge retention time (SRT) by ASSR addition, and the reduction in heterotrophic biomass activity added to the organic compounds' hydrolysis.

scholarly journals Performance and Microbial Community Dynamics in Anaerobic Digestion of Waste Activated Sludge: Impact of Immigration

Energies ◽  
2019 ◽  
Vol 12 (3) ◽  
pp. 573 ◽  
Author(s):  
Juhee Shin ◽  
Si-Kyung Cho ◽  
Joonyeob Lee ◽  
Kwanghyun Hwang ◽  
Jae Chung ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Growth Rates ◽  
Municipal Wastewater ◽  
Community Dynamics ◽  
Oxygen Demand ◽  
Waste Activated Sludge ◽  
Municipal Wastewater Treatment ◽  
Microbial Community Dynamics ◽  
Ch4 Production

Waste activated sludge (WAS) is a byproduct of municipal wastewater treatment. WAS contains a large proportion of inactive microbes, so when it is used as a substrate for anaerobic digestion (AD), their presence can interfere with monitoring of active microbial populations. To investigate how influent cells affect the active and inactive microbial communities during digestion of WAS, we operated model mesophilic bioreactors with conventional conditions. Under six different hydraulic retention times (HRTs; 25, 23, 20, 17, 14, and 11.5 d), the chemical oxygen demand (COD) removal and CH4 production of the AD were within a typical range for mesophilic sludge digesters. In the main bacteria were proteobacteria, bacteroidetes, and firmicutes in both the WAS and the bioreactors, while in main archaeal methanogen group was Methanosarcinales in the WAS and methanomicrobiales in the bioreactors. Of the 106 genera identified, the estimated net growth rates were negative in 72 and positive in 34. The genera with negative growth included many aerobic taxa. The genera with positive growth rates included methanogens and syntrophs. In some taxa, the net growth rate could be positive or negative, depending on HRT, so their abundance was also affected by HRT. This study gives insights into the microbial dynamics of a conventional sludge anaerobic digester by distinguishing potentially active (growing) and inactive (non-growing, dormant) microbes and by correlating population dynamics with process parameters.

Environmental performance of an integrated fixed-film activated sludge (IFAS) reactor treating actual municipal wastewater during start-up phase

2015 ◽  
Vol 72 (10) ◽  
pp. 1840-1850 ◽  
Author(s):  
Nitin Kumar Singh ◽  
Absar Ahmad Kazmi ◽  
Markus Starkl
Keyword(s):  
Activated Sludge ◽  
Pathogenic Bacteria ◽  
Municipal Wastewater ◽  
Oxygen Demand ◽  
Pilot Scale ◽  
Lessons Learned ◽  
Present System ◽  
Salmonella Spp ◽  
Start Up ◽  
Fixed Film

The present study summarizes the start-up performance and lessons learned during the start-up and optimization of a pilot-scale plant employing integrated fixed film activated sludge (IFAS) process treating actual municipal wastewater. A comprehensive start-up was tailored and implemented to cater for all the challenges and problems associated with start-up. After attaining desired suspended biomass (2,000–3,000 mg/L) and sludge age (∼7 days), the average biological oxygen demand (BOD) and chemical oxygen demand (COD) removals were observed as 77.3 and 70.9%, respectively, at optimized conditions, i.e. hydraulic retention time (HRT), 6.9 h; return sludge rate, 160%. The influent concentrations of COD, BOD, total suspended solids, NH3-N, total nitrogen and total phosphorus were found to be in the range of 157–476 mg/L, 115–283 mg/L, 152–428 mg/L, 23.2–49.3 mg/L, 30.1–52 mg/L and 3.6–7.8 mg/L, respectively, and the minimum effluent concentrations were achieved as ∼49 mg/L, 23 mg/L, 35 mg/L, 2.2 mg/L, 3.4 mg/L and 2.8 mg/L, respectively, at optimum state. The present system was found effective in the removal of pathogenic bacteria (Escherichia coli, 79%; Salmonella spp., 97.5%; Shigella spp., 92.9%) as well as coliforms (total coliforms, 97.65%; faecal coliforms, 80.35%) without any disinfection unit. Moreover it was observed that the time required for the stabilization of the plant was approximately 3 weeks if other parameters (sludge age, HRT and dissolved oxygen) are set to optimized values.

scholarly journals Initiating Biodegradation of Polyvinylpyrrolidone in an Aqueous Aerobic Environment: Technical Note / Zainicjowanie Biodegradacji Poliwinylopirolidonu W Środowisku Wodno-Tlenowym: Notatki Techniczne

2013 ◽  
Vol 20 (1) ◽  
pp. 199-208 ◽  
Author(s):  
Marketa Julinova ◽  
Jan Kupec ◽  
Roman Slavik ◽  
Maria Vaskova
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Municipal Wastewater ◽  
Waste Treatment ◽  
Wastewater Treatment Plants ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Technical Note ◽  
Aerobic Biodegradation ◽  
Municipal Wastewater Treatment

Abstract A synthetic polymer, polyvinylpyrrolidone (PVP - E 1201) primarily finds applications in the pharmaceutical and food industries due to its resistance and zero toxicity to organisms. After ingestion, the substance passes through the organism unchanged. Consequently, it enters the systems of municipal wastewater treatment plants (WWTP) without decomposing biologically during the waste treatment process, nor does it attach (through sorption) to particles of activated sludge to any significant extent, therefore, it passes through the system of a WWTP, which may cause the substance to accumulate in the natural environment. For this reason the paper investigates the potential to initiate aerobic biodegradation of PVP in the presence of activated sludge from a municipal wastewater treatment plant. The following agents were selected as the initiators of the biodegradation process - co-substrates: acrylamide, N-acethylphenylalanine and 1-methyl-2-pyrrolidone, a substance with a similar structure to PVP monomer. The biodegradability of PVP in the presence of co-substrates was evaluated on the basis of biological oxygen demand (BOD) as determined via a MicroOxymax O2/CO2/CH4 respirometer. The total substrate concentration in the suspension equaled 400 mg·dm-3, with the ratio between PVP and the cosubstrate being 1:1, while the concentration of the dry activated sludge was 500 mg·dm-3. Even though there was no occurrence of a significant increase in the biodegradation of PVP alone in the presence of a co-substrate, acrylamide appeared to be the most effective type of co-substrate. Nevertheless, a recorded decrease in the slope of biodegradation curves over time may indicate that a process of primary decomposition was underway, which involves the production of metabolites that inhibit activated sludge microorganisms. The resulting products are not identified at this stage of experimentation.

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