The assessment of different operating strategies for minimising activated sludge deflocculation under temperature transient conditions

2004 ◽  
Vol 50 (3) ◽  
pp. 67-77 ◽  
Author(s):  
F. Morgan-Sagastume ◽  
D. Grant Allen
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Pulp Mill ◽  
Temperature Shift ◽  
Batch Reactors ◽  
Substrate Removal ◽  
Removal Capacity ◽  
Floc Structure ◽  
Fundamental Research ◽  
Operating Strategies

Three operating strategies were tested for decreasing activated sludge deflocculation due to temperature shifts from 30° to 45°C: magnesium sludge enrichment, increased sludge retention time (33 d), and spikes of an easily degradable substrate (methanol). The temperature shifts were conducted sequentially in 4 parallel lab-scale sequencing batch reactors (SBRs) treating kraft pulp mill effluent. Three SBRs operated at an SRT = 20 days, and in one of them the sludge was not manipulated, thus, serving as a reference SBR. The temperature shift was associated with decreased soluble chemical oxygen demand (SCOD) removals, decreased sludge settleability and substrate removal capacity, and increased effluent suspended solids (ESS) and turbidity levels. The shift also increased the sludge specific respiration rates and reduced the sludge substrate removal capacity. Sludge deflocculation was assessed as floc solubilisation (increased effluent SCOD levels) and floc fragmentation (increase in effluent solids smaller than 50 mm). Mg enrichment of the sludge and methanol spikes reduced the ESS levels (in 9 and 25%), and the three operating strategies decreased effluent turbidity (in 22-35%) compared to the maximum levels from the non-manipulated reactor (44 mg ESS/L). The stronger sludge floc structure achieved by magnesium enrichment and a high sludge age of 33 days was unsuccessful in significantly decreasing deflocculation. The mechanisms involved in sludge deflocculation require further fundamental research.

Are some putative glycogen accumulating organisms (GAO) in anaerobic : aerobic activated sludge systems members of the α-Proteobacteria?

Microbiology ◽  
2004 ◽  
Vol 150 (7) ◽  
pp. 2267-2275 ◽  
Author(s):  
Michael Beer ◽  
Yun H. Kong ◽  
Robert J. Seviour
Keyword(s):  
Activated Sludge ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Bacterial Populations ◽  
Removal Capacity ◽  
Large Numbers ◽  
Gradient Gel Electrophoresis ◽  
Polyphosphate Accumulating Organisms

Activated sludge plants designed to remove phosphorus microbiologically often perform unreliably. One suggestion is that the polyphosphate-accumulating organisms (PAO) are out-competed for substrates by another group of bacteria, the glycogen-accumulating organisms (GAO) in the anaerobic zones of these processes. This study used fluorescence in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE) to analyse the communities from laboratory-scale anaerobic : aerobic sequencing batch reactors. Members of the genus Sphingomonas in the α-Proteobacteria were present in large numbers in communities with poor phosphorus removal capacity where the biomass had a high glycogen content. Their ability to store poly-β-hydroxyalkanoates anaerobically, but not aerobically, and not accumulate polyphosphate aerobically is consistent with these organisms behaving as GAO there. No evidence was found to support an important role for the γ-Proteobacteria as possible GAO in these communities, although these bacterial populations have been considered in other studies to act as possible competitors for the PAO.

Occurrence of Microthrix parvicella in sequencing batch reactors

2014 ◽  
Vol 69 (10) ◽  
pp. 1984-1995 ◽  
Author(s):  
Lana Mallouhi ◽  
Ute Austermann-Haun
Keyword(s):  
Activated Sludge ◽  
Municipal Wastewater ◽  
Batch Reactor ◽  
Oxygen Demand ◽  
Volume Index ◽  
Batch Reactors ◽  
Sequencing Batch Reactors ◽  
Municipal Wastewater Treatment ◽  
Nitrogen And Phosphorus ◽  
Microthrix Parvicella

Sequencing batch reactors (SBRs) are known for high process stability and usually have a good sludge volume index (SVI). Nevertheless, in many SBRs in Germany for municipal wastewater treatment, scum and foam problems can occur, and SVI can be larger than 200 mL/g. The microscopic investigations of the activated sludge from plants with nitrogen and phosphorus removal have shown that Microthrix parvicella is dominant in the activated sludge in most of them. Studies showed that the optimum growth of M. parvicella is performed at a high sludge age (>20 d) and low sludge load in the range of 0.05–0.2 kg of biochemical oxygen demand per kg of total suspended solids per day (kg BOD5/(TSS·d)). The investigations in 13 SBRs with simultaneous aerobic sludge stabilization (most of them are operated with a system called differential internal cycle strategy sequential batch reactor (DIC-SBR)) show that M. parvicella is able to grow in sludge loads less than 0.05 kg BOD5/(kg TSS·d) as well. To optimize the operation of those SBRs, long cycle times (8–12 h) and dosing of iron salts to eliminate long-chain fatty acids are both recommended. This leads to better SVI and keeps M. parvicella at a low frequency.

Grease biodegradation: is bioaugmentation more effective than natural populations for start-up?

1996 ◽  
Vol 34 (5-6) ◽  
pp. 303-308 ◽  
Author(s):  
Leopoldo Mendoza-Espinosa ◽  
Tom Stephenson
Keyword(s):  
Activated Sludge ◽  
Natural Populations ◽  
Oxygen Demand ◽  
Cod Removal ◽  
Batch Reactors ◽  
Optimum Conditions ◽  
Start Up ◽  
Degradation Rates ◽  
Activated Sludge Reactor ◽  
Micro Organisms

Investigations were undertaken in order to compare the grease degradation rates for a natural population of acclimatised activated sludge micro-organisms with a commercial bioaugmentation product (bioadditive) under optimum conditions in laboratory-scale batch reactors. Lard was chosen as the source of grease because it contains the fatty acids more commonly found in urban wastewaters. During acclimatisation, the bioadditive reactor achieved a slightly better chemical oxygen demand (COD) removal efficiency than the activated sludge reactor. Therefore, under optimum conditions, activated sludge was able to degrade grease at nearly the same rate as a bioadditive solution. Moreover, the bioadditive and the activated sludge reactors had very similar kinetics of COD removal under different grease concentrations. It was concluded that the use of natural activated sludge micro-organisms was sufficient to acclimatise biological processes to removing grease.

PACTTM process for treatment of kraft mill effluent

1997 ◽  
Vol 35 (2-3) ◽  
pp. 283-290 ◽  
Author(s):  
R. M. Narbaitz ◽  
R. L. Droste ◽  
L. Fernandes ◽  
K. J. Kennedy ◽  
D. Ball
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Pulp Mill ◽  
Operating Conditions ◽  
Activated Sludge Process ◽  
Conventional Activated Sludge ◽  
Adsorbable Organic Halides ◽  
Organic Halides ◽  
Solids Retention ◽  
Year 2000

The PACTTM process (powdered activated carbon addition to the activated sludge process) was evaluated for the treatment of Kraft pulp mill wastewater in a series of bench scale experiments. Possibly due to the relatively low strength wastewater, the PACTTM process with carbon doses between 0.5 and 1.0 g/L of influent only performed marginally better than the conventional activated sludge process. Chemical oxygen demand and toxicity, evaluated with the Microtox® assay, were among the parameters monitored. For the operating conditions tested the solids retention time had no impact on performance. The main improvement was increased in adsorbable organic halides (AOX) removal, the magnitude of the improvement was dependent on the wastewater batch and the carbon dose. However conventional activated sludge treatment will meet Ontario's year 2000 AOX regulations. An empirical model from the literature described the data fairly well.

Substrate removal and sludge production in a batch activated-sludge process with blending

1982 ◽  
Vol 9 (3) ◽  
pp. 558-566 ◽  
Author(s):  
Ronald L. Droste ◽  
Jatinder K. Bewtra
Keyword(s):  
Oxygen Uptake ◽  
Activated Sludge ◽  
Oxygen Uptake Rate ◽  
Oxygen Demand ◽  
Effluent Quality ◽  
Mixed Liquor ◽  
Substrate Removal ◽  
Uptake Rates ◽  
Absorption Phenomenon ◽  
Similar Unit

Bench-scale studies were conducted on a batch-operated, activated-sludge system in which the mixed liquor was blended periodically in an Osterizer blender. A similar unit without mechanical blending was operated as a control. Synthetic organic feed of known characteristics was used as a substrate. Tests were conducted for mixed liquor volatile suspended solids (MLVSS), effluent chemical oxygen demand (COD), settleability, and oxygen uptake rate under steady-state conditions.Substrate uptake in both units was observed to be a rapid adsorption–absorption phenomenon. The nonremovable COD was significantly lower in the blended unit. Also, the oxygen uptake rates showed significant increases due to floc breakup. Settleability was good in the blended unit and the overall effluent quality had improved considerably.

Evaluation of aerobic and anaerobic treatment of Kraft pulp mill effluent for organochlorines removal

2006 ◽  
Vol 1 (3) ◽  
Author(s):  
A. P. Buzzini ◽  
M. A. Nolasco ◽  
A. M. Springer ◽  
E. C. Pires
Keyword(s):  
Activated Sludge ◽  
Black Liquor ◽  
Oxygen Demand ◽  
Pulp Mill ◽  
Anaerobic Treatment ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Individual Values ◽  
Activated Sludge Reactor

The purposes of the experiments described in this paper were to evaluate the performance of an upflow anaerobic sludge blanket (UASB) activated sludge reactor, both bench scale reactors, in the treatment of wastewaters containing organochlorines compounds, which simulate a kraft plant wastewater. Both reactors received a wastewater prepared with diluted black liquor and a mixture of organochlorines: 2 Chlorophenol (2 CP); 2,4 Dichlorophenol (2,4 DCP); 2,6 Dichlorophenol (2,6 DCP); 2,4,6 Trichlorophenol (2,4,6 TCP); and Tetrachlorocatechol (TeCC). The activated sludge reactor also received 4, 5, 6 Trichloroguaiacol (4, 5, 6 TCG). The chemical oxygen demand (COD) and organochlorine concentrations in the effluent indicated that the two systems displayed a similar performance in terms of COD removal, with average efficiencies of 79% for the UASB reactor and of 77% for the activated sludge reactor. The average individual values for organochlorine removal efficiency, the first figure representing the UASB reactor removal, were: 99.9% and 91% for the 2 CP; 97% and 80% for the 2,4 DCP; 94% and 80% for the 2,6 DCP; 99% and 75% for the 2,4,6 TCP; and 93% and 90% for the TeCC. Both systems showed to be capable of treating pulp plant wastewaters containing chlorophenols, with a certain advantage for the anaerobic system from the standpoint of removal efficiencies.

Biological activity of bleached kraft pulp mill effluents before and after activated sludge and ozone treatments

2013 ◽  
Vol 67 (2) ◽  
pp. 333-339 ◽  
Author(s):  
Alessandra Cunha Lopes ◽  
Ann H. Mounteer ◽  
Teynha Valverde Stoppa ◽  
Davi Santiago Aquino
Keyword(s):  
Biological Activity ◽  
Activated Sludge ◽  
Kraft Pulp ◽  
Chronic Toxicity ◽  
Estrogenic Activity ◽  
Oxygen Demand ◽  
Pulp Mill ◽  
Ozone Treatment ◽  
Kraft Pulp Mill ◽  
Bleached Kraft Pulp

Eucalyptus bleached kraft pulp production, an important sector of the Brazilian national economy, is responsible for generating large volume, high pollutant load effluents, containing a considerable fraction of recalcitrant organic matter. The objectives of this study were to quantify the biological activity of the effluent from a eucalyptus bleached kraft pulp mill, characterize the nature of compounds responsible for biological activity and assess the effect of ozone treatment on its removal. Primary and secondary effluents were collected bimonthly over the course of one year at a Brazilian bleached eucalypt kraft pulp mill and their pollutant loads (biochemical oxygen demand (BOD), chemical oxygen demand (COD), total organic carbon (TOC), adsorbable organic halogen (AOX), lignin, extractives) and biological activity (acute and chronic toxicity and estrogenic activity) quantified. The effluent studied did not present acute toxicity to Daphnia, but presented the chronic toxicity effects of algal growth inhibition and reduced survival and reproduction in Ceriodaphnia, as well as estrogenic activity. Chronic toxicity and estrogenic activity were reduced but not eliminated during activated sludge biological treatment. The toxicity identification evaluation revealed that lipophilic organic compounds (such as residual lignin, extractives and their byproducts) were responsible for the toxicity and estrogenic activity. Ozone treatment (50 mg/L O3) of the secondary effluent eliminated the chronic toxicity and significantly reduced estrogen activity.

scholarly journals Determination of inert Chemical Oxygen Demand (COD) fractions of Cumhuriyet University wastewater

2013 ◽  
Vol 8 (1) ◽  
pp. 31-36
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Batch Reactor ◽  
Treatment Plant ◽  
Oxygen Demand ◽  
Batch Reactors ◽  
Biological Degradation ◽  
University Campus ◽  
Activated Sludge System ◽  
Wastewater Samples

Some amounts of inert products are given into environment due to biological degradation of substrate in activated sludge system. The effluent of biological wastewater treatment consists of inert substrate in influent flow, soluble microbial products and non degradable or slowly degradable organic products. Soluble inert COD (SI) must be determined for discharge standards since it did not give any reaction in activated sludge system and was given with wastewater discharge. However particular inert COD (XI) accumulated in system depending on sludge retention time due to it is only wasted from system by wasted sludge. This study focused on inert fractions of Cumhuriyet University campus wastewater which consists of domestic, hospital and laboratory wastewaters. Experimental method was used suggested by Orhon et al. and modified by Germirli et al. in order to determine directly influent particulate and soluble inert fractions. According to the experimental procedure three aerobic batch reactors, two with the wastewater and the third with glucose were run parallel. In the reactors, the change in the soluble COD profiles is observed for a period during which all degradable COD is entirely depleted, in other words, the COD profiles reach a plateau and remain unchanged. Wastewater samples were taken equalization tank in wastewater treatment plant. The conventional parameters of campus wastewater characterization were as follows: Total COD (CT0) = 372 mg l-1, total soluble COD (STO) = 124 mg l-1, total suspended solids (TSS) =177 mg l-1, ammonia (NH3) = 31.2 mg l-1, ortho-phosphate (PO4-P) = 11.3 mg l-1 and pH=7,4 . In this study, in order to determine inert COD fractions in Cumhuriyet University campus wastewater, three aerobic batch reactor systems were used. At the end of approximately 381 h operation, COD composition of campus wastewater were found to be CT0=372 mg l-1, XS0=56 mg l-1, SS0=104 mg l-1, CS0=149 mg l-1, SI=12 mg l-1, XI=211 mg l-1, respectively.

scholarly journals Rapid cultivation of aerobic granular sludge by xanthan gum in SBR reactors

2018 ◽  
Vol 2017 (2) ◽  
pp. 360-369 ◽  
Author(s):  
Sha Liu ◽  
Hanhui Zhan ◽  
Yaqi Xie ◽  
Weijiang Shi ◽  
Siming Wang
Keyword(s):  
Activated Sludge ◽  
Xanthan Gum ◽  
Oxygen Demand ◽  
Granular Sludge ◽  
Surface Characteristics ◽  
Aerobic Granular Sludge ◽  
Batch Reactors ◽  
Close Monitoring ◽  
Sludge Granulation ◽  
Aerobic Sludge

Abstract This study focuses on the effect of xanthan gum on aerobic sludge granulation, through close monitoring of the physical and chemical changes of the aerobic granular sludge, and treatment performance. Two sequencing batch reactors (SBRs), R1 and R2, were seeded with activated sludge only (R1) and with a mixture of activated sludge and 40 mg/L of xanthan gum (R2). The results showed that granulation finished on the 20th day in R2, far faster than the granulation time of 30 days in R1. Meanwhile, there was a reliably higher sludge concentration, better settling properties and better particle mechanical strength in R2, and better removal performance of total nitrogen (TN) and chemical oxygen demand (COD). The results demonstrated that seeding xanthan gum enhanced the aerobic sludge granulation in the SBR. Maybe its anionic and hydrophilic surface characteristics facilitate interactions with cations and other polysaccharides, inducing stronger gelation, which promoted the formation of particles or increased the internal relationship between particles, thereby increasing the cohesion within the sludge, so that the granular sludge was not easily broken.

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