Clarifier Performance in Activated Sludge Process Treating Pulp and Paper Mill Effluents

1994 ◽  
Vol 29 (5-6) ◽  
pp. 313-328 ◽  
Author(s):  
Sakari Halttunen
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Paper Industry ◽  
Paper Mill ◽  
Field Studies ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Paper Mill Effluents ◽  
Sludge Settling ◽  
Activated Sludge Processes

High suspended solids concentrations are typical for pulp and paper industry treated effluents. A new clarifier model was developed to find the reasons for this problem. The model clarifier is divided into four different zones: inlet, settling, thickening and separation. In the inlet zone sludge is transported by water flow and neither thickening nor settling will happen. When water velocity decreases the main part of the sludge will settle until it reaches the thickening zone. Thickening will continue until the sludge is pumped away from the clarifier. Concentration increase depends on sludge concentration, time and specific thickening coefficient. The minor part, which is specific to the sludge, enters the separation zone and will either settle in the thickening zone or stay in the effluent. In intensive field studies on 12 different activated sludge processes sludge volume in the clarifier, effluent suspended solids concentrations and sludge settling qualities were examined. Modelled sludge blanket volumes were verified with blanket measurements. Modelled effluent suspended solids were also verified by concentration measurements. Sludge thickening characteristics can be estimated by DSVI. From the data collected two empirical relationships were noticed between sludge settling properties and process operation. Solids concentration in clarified water depends on settling number, which is the mean number of sludge settling during its residence time in the process (sludge age). Sludge settling properties seem to depend on collision load, which is defined as COD-load divided by return sludge biomass flow.

Regulatory Requirements for Pulp and Paper Mill Effluent Control: Scientific Basis and Consequences

1991 ◽  
Vol 24 (3-4) ◽  
pp. 19-31 ◽  
Author(s):  
J. Folke
Keyword(s):  
Suspended Solids ◽  
Paper Industry ◽  
Paper Mill ◽  
Pulp And Paper ◽  
Hazardous Substances ◽  
Pulp And Paper Mill ◽  
Indirect Measure ◽  
Paper Mill Effluent ◽  
Paper Mill Effluents ◽  
Hazardous Compounds

The Ministers' Declaration from the 2nd North Sea Conference recommended a goal to be set to diminish the discharge of hazardous substances via rivers by 50% over the next 10 years, e.g. to diminish the discharge of persistent halogenated compounds from pulp and paper mill effluents. The Paris Convention adopted this recommendation later. Based on a study conducted for the EEC Commission, we have arrived at the following conclusions to fulfil this goal. For historic reasons the regulation of the pulp and paper industry includes some parameters which may not be the most appropriate ones, e.g. BOD5 and AOX. To regulate the bleached pulp mills by AOX/TOC1 is not recommendable. PCDD/PDDFs are very difficult to regulate at present. Regulation of polychlorinated phenolics (PoCPs) in the effluent may prove to be a valid indirect measure of TCDD-equivalents, but this has yet to be proven. To ensure sufficient removal of hazardous compounds, we recommend that standards for TSS be stringent, as the major fraction of hazardous compounds is associated with suspended solids (including PoCPs and PCDD/PCDFs). Effluent control should be based on pH, COD (Chemical Oxygen Demand using dichromic acid), TSS (total suspended solids) and PoCPs. At present there are not sufficient data available to establish a regulation based on these parameters. So, further data should be obtained.

Mutagenicity in Pulp and Paper Mill Effluents and in Recipient

1988 ◽  
Vol 20 (2) ◽  
pp. 143-152 ◽  
Author(s):  
A. Langi ◽  
M. Priha
Keyword(s):  
Activated Sludge ◽  
Mutagenic Activity ◽  
Chinese Hamster Ovary Cells ◽  
Chinese Hamster ◽  
Paper Mill ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Sludge Treatment ◽  
Paper Mill Effluents ◽  
Kraft Mill

The mutagenic properties of pulp and paper mill effluents were studied in three mills: bleached kraft mill with aerated lagoon treatment (Mill 1), bleached kraft mill with activated sludge treatment (Mill 2) and mechanical pulp/paper mill (Mill 3). Both treated and untreated effluents, process streams and molecular fractions were tested for mutagenicity (Ames test. Salmonella typhimurium TA100 and SCE sister chromatid exchange test, Chinese hamster ovary cells). To verify the potential environmental effects the mutagenic activity of concentrated recipient lake water (Mill 2) was also studied. The Ames mutagenicity of the bleached kraft mill effluent (BKME) originated from the first chlorination filtrate, SCE mutagenicity also occurred in the alkali extraction stage filtrate (Mill 1). No Ames mutagenicity was detected in the paper mill effluent, but it was SCE mutagenic. Activated sludge treatment of BKME removed both Ames and SCE mutagenicity, but the aerated lagoon treated BKME was still SCE mutagenic. No mutagenic activity was detected in the recipient water concentrates.

A new optical method for measuring suspended solids in pulp and paper mill effluents

1980 ◽  
Vol 13 (12) ◽  
pp. 9-22
Author(s):  
G. Fladda ◽  
T. Pettersson ◽  
L. Eriksson ◽  
G. Tidstam
Keyword(s):  
Optical Method ◽  
Suspended Solids ◽  
Paper Mill ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Paper Mill Effluents

A New Optical Method for Measuring Suspended Solids in Pulp and Paper Mill Effluents

1980 ◽  
Vol 13 (4) ◽  
pp. 9-22 ◽  
Author(s):  
G. Fladda ◽  
T. Pettersson ◽  
L. Eriksson ◽  
G. Tidstam
Keyword(s):  
Optical Method ◽  
Suspended Solids ◽  
Paper Mill ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Paper Mill Effluents

Molecular characterization of microbial communities in Canadian pulp and paper activated sludge and quantification of a novelThiothrix eikelboomii-like bulking filament

2006 ◽  
Vol 52 (5) ◽  
pp. 494-500 ◽  
Author(s):  
Tim J Dumonceaux ◽  
Janet E Hill ◽  
Carl P Pelletier ◽  
Michael G Paice ◽  
Andrew G Van Kessel ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Microbial Community ◽  
Activated Sludge ◽  
Type Strain ◽  
Suspended Solids ◽  
Paper Mill ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Chaperonin 60 ◽  
Paper Mill Wastewater

We examined the microbial community structure and quantified the levels of the filamentous bulking organism Thiothrix eikelboomii in samples of activated sludge mixed liquor suspended solids (MLSS) from Canadian pulp and paper mills. Libraries of chaperonin 60 (cpn60) gene sequences were prepared from MLSS total microbial community DNA and each was compared with cpnDB, a reference database of cpn60 sequences (http://cpndb.cbr.nrc.ca) for assignment of taxonomic identities. Sequences similar to but distinct from the type strain of T. eikelboomii AP3 (ATCC 49788T) (~89% identity over 555 bp) were recovered at high frequency from a mill sample that was experiencing bulking problems at the time of sample collection, which corresponded to microscopic observations using fluorescent in situ hybridization with commercially available 16S rDNA-based probes. We enumerated this strain in five mill-derived MLSS samples using real-time quantitative PCR (qPCR) and found that two samples had high levels of the bulking strain (>1012genomes/g MLSS) and two contained lower but detectable levels of this organism. None of the mill samples contained cpn60 sequences that were identical to the type strain of T. eikelboomii. This technique shows promise for monitoring pulp and paper mill wastewater treatment systems by detecting and enumerating this strain of T. eikelboomii, which may be specific to pulp and paper mill wastewater treatment systems.Key words: activated sludge, biological treatment, bulking; chaperonin 60, cpn60, filamentous bacteria, mixed liquor suspended solids, microbial communities, 021N, qPCR, settling, Thiothrix.

Anaerobic treatment of pulp and paper mill effluents – status quo and new developments

2007 ◽  
Vol 55 (6) ◽  
pp. 223-230 ◽  
Author(s):  
Leo Habets ◽  
Willie Driessen
Keyword(s):  
Paper Industry ◽  
Industrial Effluents ◽  
Paper Mill ◽  
Anaerobic Treatment ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Widespread Application ◽  
Paper Mills ◽  
Paper Mill Effluents ◽  
Pre Treatment

Since the early 1980s, anaerobic treatment of industrial effluents has found widespread application in the pulp and paper industry. Over 200 installations are treating a large variety of different pulp and paper mill effluents. Amongst various anaerobic systems the UASB and IC are the most applied anaerobic reactor systems. Anaerobic treatment is well feasible for effluents originated from recycle paper mills, mechanical pulping (peroxide bleached), semi-chemical pulping and sulphite and kraft evaporator condensates. The advantages of anaerobic pre-treatment are (1) net production of renewable energy (biogas), (2) minimized bio-solids production, (3) minimal footprint and (4) reduced emission of greenhouse gases. Via in-line application of anaerobic treatment in closed circuits (paper kidney technology) further savings on cost of fresh water intake and effluent discharge levies are generated.

Effect of ozonation on activated sludge from pulp and paper industry

2010 ◽  
Vol 62 (7) ◽  
pp. 1676-1681 ◽  
Author(s):  
S. Gupta ◽  
S. K. Chakrabarti ◽  
S. Singh
Keyword(s):  
Activated Sludge ◽  
Paper Industry ◽  
Bacterial Biomass ◽  
Cost Effective ◽  
Paper Mill ◽  
Pulp And Paper Industry ◽  
Pulp And Paper ◽  
Pulp And Paper Mill ◽  
Secondary Sludge ◽  
Predominant Process

Aerobic biological treatment with activated sludge is the predominant process all over the world for treatment of pulp and paper industry wastewater. 50–70% of the biodegradable organic material is oxidized to CO2 and the rest is converted to bacterial biomass, typically termed as excess sludge or waste activated sludge (WAS). Handling and disposal of WAS in general and in particular from the pulp and paper industry face different processing difficulties, regulatory stringency due to organochlorine contamination and reluctance of people for reuse. With an objective of reducing the net disposable biomass, ozonation of WAS from a pulp and paper mill and from a laboratory scale batch activated sludge process operated with the wastewater and bacterial seed of the same pulp and paper mill have been carried out. With the mill sludge having predominant filamentous organisms 18% MLSS was reduced at an ozone dosage of 55 mg O3/g dry MLSS solid (DS) resulting in 2.5 times COD increase. With the laboratory sludge which is well structured and flocculating, only 6% MLSS was reduced at an ozone dosage of 55 mg O3/g DS. Ozonation mineralizes 26% and 20% AOX compounds embedded in the secondary sludge in the mill and laboratory sludge respectively at an ozone dosage of 55 mg O3/g DS. During ozonation, absorbed/adsorbed lignin on biomass was released which resulted in increased colour concentration. Ozonation can be a potential oxidative pretreatment process for reducing the WAS and paving the way for cost effective overall treatment of WAS.

The formation of colour during biological treatment of pulp and paper wastewater

2004 ◽  
Vol 50 (3) ◽  
pp. 87-94 ◽  
Author(s):  
C.B. Milestone ◽  
R.R. Fulthorpe ◽  
T.R. Stuthridge
Keyword(s):  
Activated Sludge ◽  
Paper Industry ◽  
Paper Mill ◽  
Anaerobic Treatment ◽  
Subsequent Treatment ◽  
Pulp And Paper ◽  
Effluent Treatment ◽  
Pulp And Paper Mill ◽  
Anaerobic Conditions ◽  
Significant Change

Colour discharges are gaining renewed focus in the pulp and paper industry as increasingly strict regulatory limits are placed on wastewater quality and aesthetics. In-mill process improvements, such as ECF bleaching and oxygen delignification, have decreased wastewater colour loadings. However, a survey of 12 pulp and paper mill systems found that effluent treatment using aerated stabilisation basins (ASB) leads to average increases in colour of 20-40%. In some instances, this phenomenon may even double the influent colour levels. Activated sludge systems did not produce a colour increase. The measured increases that follow ASB secondary treatment may be sufficient for a mill to fail prescribed discharge standards. A detailed field survey focusing on sections of an integrated bleached kraft mill ASB treatment system was undertaken. The average increase in colour at the final point of discharge was 45%. The major changes in colour concentration occurred in the inlet to the main treatment pond, and in polishing ponds that followed the main treatment pond. Both of these areas receive little or no aeration. No significant change was observed in the highly aerated main pond. These results, along with literature reports, suggested that redox conditions play a major role in influencing colour behaviour. To test this, two series of paired continuously stirred reactors were used to treat whole mill effluent from two ECF bleached kraft mills in parallel. The first series initially treated under anaerobic conditions, followed by an aerobic reactor, while the second series reversed this order. With the initial anaerobic stage, effluent colour increased by 18% and 19% for the first and second series respectively. Subsequent treatment by aerobic bacteria further increased colour by 14% and 6%, for a total increase of 32% and 25%. Initial aerobic treatment, however, did not lead to any significant change in colour for either effluent. Further anaerobic treatment following aerobic conditions produced only small increases in colour. These results are consistent with the ASB and activated sludge system survey, suggesting that anaerobic conditions at the head of treatment systems initiate the observed increases in effluent colour in ASB treatment systems.

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