Influence of chemically enhanced primary treatment on anaerobic digestion and dewaterability of waste sludge

To lower energy consumption at a sewage treatment plant (STP), primary settling could be enhanced to direct more chemical oxygen demand (COD) to anaerobic digestion (AD) for increased biogas production and decreased aeration. Primary settling can be chemically enhanced by applying flocculation aids (FAs). FAs are refractory compounds that may affect all sludge treatment facilities. In this study the consequences are investigated of the application of FAs for chemically enhanced primary treatment (CEPT) on AD and subsequent dewatering of digested sludge in a conventional STP. It was found that FAs maintain their effect throughout all sludge processing facilities. With CEPT, more readily degradable solids were removed, resulting in a higher bio methane potential of the primary sludge. In AD, FAs lowered the viscosity; meanwhile an increased hydrolysis rate was observed. But FAs also partially irreversibly bound substrate in such way that it is not available for biological degradation anymore. In subsequent dewatering of digested sludge, a higher dry solids concentration was observed with CEPT. A computer simulation showed that in a conventional STP, CEPT would not be economically feasible. However, several benefits were discussed that can make CEPT an interesting option for future low COD/N-tolerant STPs with, for example, Anammox processes for N removal.

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Increasing microbial activity in thermophilic anaerobic digestion of physicochemical sludge

Water Science & Technology ◽

10.2166/wst.2006.512 ◽

2006 ◽

Vol 54 (2) ◽

pp. 245-251

Author(s):

A. Tinajero ◽

A. Noyola

Keyword(s):

Biogas Production ◽

Treatment Plant ◽

Primary Treatment ◽

Fecal Coliforms ◽

Salmonella Spp ◽

Digested Sludge ◽

Class A ◽

Effect Of Additives ◽

Thermophilic Anaerobic Digestion ◽

Chemically Enhanced Primary Treatment

Two thermophilic lab-scale reactors of 5 L were operated on a daily fed basis. Digester T1 received raw sludge (control) and digester T2 was fed with raw sludge plus metallic micronutrients and a bacilli additive. Raw sludge was obtained from a municipal chemically enhanced primary treatment plant. The effect of additives was clear on methane production, since on day 50, digester T2 produced 900 ml more methane than T1, an increase of 64%. On day 80, T2 reached twice the production of biogas of T1. Volatile solid removal (% VSR) in T2 increased to 29%; while T1 achieved only 15%. Acetic acid concentration in T2 diminished to 100 mg/L, which related to the higher biogas production. Based on the Mexican biosolids standard, the digested sludge reached Class A biosolids, in both digesters: fecal coliforms were reduced to less than 1000 MPN/gTS; Salmonella spp was totally eliminated and helminth egg counts were lower than one viable egg per gram of total solids.

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Characterization of raw sludge, chemically modified sludge and anaerobically digested sludge in Hong Kong

Water Science & Technology ◽

10.2166/wst.1998.0095 ◽

1998 ◽

Vol 38 (2) ◽

pp. 25-32 ◽

Cited By ~ 2

Author(s):

C. W. Chu ◽

C. S. Poon ◽

R. Y. H. Cheung

Keyword(s):

Hong Kong ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Chemical Properties ◽

Primary Treatment ◽

Digested Sludge ◽

Total N ◽

Chemically Modified ◽

Anaerobically Digested Sludge

Chemically Enhanced Primary Treatment (CEPT) or Chemically Assisted Primary Sedimentation (CAPS) is being employed at the new sewage work on Stonecutters Island as part of the Strategic Sewage Disposal Scheme (SSDS) in Hong Kong. CAPS involves the use of chemical coagulants (such as lime or ferric chloride) to induce coagulation or flocculation and let these finely-divided particles form large aggregates (floc) so that they can settle out within a reasonable period of time. In this study, five sludge samples collected from different sewage treatment plants in Hong Kong were physically and chemically characterized. They were chemically modified sludge from Stonecutters Island (CAPS) raw sludge from Tai Po and Yuen Long Sewage Treatment Plant (STP) (rTP & rYL) and anaerobically digested sludge from Tai Po and Yuen Long STP (dTP & dYL). It was found that CAPS sludge was better than other 4 sludge samples in terms of settleability and dewaterability. CAPS sludge contained significant higher amounts (p<0.01) of extractable compounds than other sludges (except NO3− for dTP, NH4+ and PO43− for dYL). The concentration of total N and P in CAPS sludge were significantly higher (p<0.01) than other sludges (except dYL). The concentrations of total Cu, Pb, Ni, Cd, Cr and K in the CAPS sludge were also significantly higher (p<0.01) than other sludge samples. Most of the metals (Cr, Pb, Cr and Zn) in CAPS sludge were associated with the organically-bounded phase. It is concluded that there are significant differences in both physical and chemical properties between the chemically modified sludge and biological treated sludges.

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Improvement of anaerobic digestion of sludge

Water Science & Technology ◽

10.2166/wst.2004.0616 ◽

2004 ◽

Vol 49 (10) ◽

pp. 89-96 ◽

Cited By ~ 57

Author(s):

M. Dohányos ◽

J. Zábranská ◽

J. Kutil ◽

P. Jeníček

Keyword(s):

Particulate Matter ◽

Anaerobic Digestion ◽

Energy Balance ◽

Activated Sludge ◽

High Resistance ◽

Biogas Production ◽

Treatment Plant ◽

Process Conditions ◽

Digested Sludge ◽

Acceptable Method

Anaerobic digestion improvement can be accomplished by different methods. Besides optimization of the process conditions, pretreatment of input sludge and increase of process temperature is frequently used. The thermophilic process brings a higher solids reduction and biogas production, a high resistance to foaming, no problems with odour, better pathogens destruction and an improvement of the energy balance of the whole treatment plant. Disintegration of excess activated sludge in a lysate centrifuge was proved to cause increase of biogas production in full-scale conditions. The rapid thermal conditioning of digested sludge is an acceptable method of particulate matter disintegration and solubilization.

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Chemically enhanced primary treatment (CEPT) for removal of carbon and nutrients from municipal wastewater treatment plants: a case study of Shanghai

Water Science & Technology ◽

10.2166/wst.2009.547 ◽

2009 ◽

Vol 60 (7) ◽

pp. 1803-1809 ◽

Cited By ~ 32

Author(s):

Hongtao Wang ◽

Fengting Li ◽

Arturo A. Keller ◽

Ran Xu

Keyword(s):

Wastewater Treatment ◽

Wastewater Treatment Plant ◽

Municipal Wastewater ◽

Treatment Plant ◽

Primary Treatment ◽

Secondary Treatment ◽

Municipal Wastewater Treatment ◽

N Removal ◽

Chemically Enhanced Primary Treatment ◽

Discharge Criteria

With Chemically Enhanced Primary Treatment (CEPT) as the short-term process, the capacity of Bailonggang Wastewater Treatment Plant accounts for almost 25% of the total capacity of wastewater treatment in Shanghai, China. However, shortly after this plant was placed in operation in 2004, it was found that the effluent of CEPT couldn't meet the new national discharge criteria. Although the removal of phosphate is almost 80%, chemical oxygen demand (COD) and ammonia nitrogen (NH3-N) in the effluent is frequently found to exceed the standards. The primary goal of this research is to investigate the possibility of optimizing the CEPT to make it meet the discharge criteria before it is upgraded to a secondary treatment. An oxidant is adopted to remove NH3-N, and a high performance polyaluminum chloride (HP-PACl) is synthesized to enhance the removal of COD. It is found that HP-PACl improves the removal of COD, and the oxidant enhances NH3-N removal effectively. However, to meet the requirement of a newly implemented stricter discharge standard, it is necessary to upgrade this CEPT to a secondary treatment. The results of this study provide scientific evidence for the upgrade of the Bailonggang Wastewater Treatment Plant.

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Life Cycle Assessment of an intensive sewage treatment plant in Barcelona (Spain) with focus on energy aspects

Water Science & Technology ◽

10.2166/wst.2011.522 ◽

2011 ◽

Vol 64 (2) ◽

pp. 440-447 ◽

Cited By ~ 26

Author(s):

L. Bravo ◽

I. Ferrer

Keyword(s):

Life Cycle Assessment ◽

Life Cycle ◽

Anaerobic Digestion ◽

Environmental Impacts ◽

Biogas Production ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Pre Treatment ◽

Energy Aspects

Life Cycle Assessment was used to evaluate environmental impacts associated to a full-scale wastewater treatment plant (WWTP) in Barcelona Metropolitan Area, with a treatment capacity of 2 million population equivalent, focussing on energy aspects and resources consumption. The wastewater line includes conventional pre-treatment, primary settler, activated sludge with nitrogen removal, and tertiary treatment; and the sludge line consists of thickening, anaerobic digestion, cogeneration, dewatering and thermal drying. Real site data were preferably included in the inventory. Environmental impacts of the resulting impact categories were determined by the CLM 2 baseline method. According to the results, the combustion of natural gas in the cogeneration engine is responsible for the main impact on Climate Change and Depletion of Abiotic Resources, while the combustion of biogas in the cogeneration unit accounts for a minor part. The results suggest that the environmental performance of the WWTP would be enhanced by increasing biogas production through improved anaerobic digestion of sewage sludge.

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Sludge minimization by disintegration at different wastewater treatment plants

Water Practice & Technology ◽

10.2166/wpt.2008.010 ◽

2008 ◽

Vol 3 (1) ◽

Author(s):

Luchien Luning ◽

Paul Roeleveld ◽

Victor W.M. Claessen

Keyword(s):

Organic Matter ◽

Wastewater Treatment ◽

Anaerobic Digestion ◽

Sewage Sludge ◽

New Technologies ◽

Wastewater Treatment Plants ◽

Treatment Plant ◽

Biological Degradation ◽

Ongoing Research ◽

Sludge Minimization

In recent years new technologies have been developed to improve the biological degradation of sewage sludge by anaerobic digestion. The paper describes the results of a demonstration of ultrasonic disintegration on the Dutch Wastewater Treatment Plant (WWTP) Land van Cuijk. The effect on the degradation of organic matter is presented, together with the effect on the dewatering characteristics. Recommendations are presented for establishing research conditions in which the effect of sludge disintegration can be determined in a more direct way that is less sensitive to changing conditions in the operation of the WWTP. These recommendations have been implemented in the ongoing research in the Netherlands supported by the National Institute for wastewater research (STOWA).

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Simulation of the Impact of Higher Ammonia Recycle Loads Caused by Upgrading Anaerobic Sludge Digesters

Water Quality Research Journal ◽

10.2166/wqrj.2005.053 ◽

2005 ◽

Vol 40 (4) ◽

pp. 491-499 ◽

Cited By ~ 2

Author(s):

Jeremy T. Kraemer ◽

David M. Bagley

Keyword(s):

Anaerobic Digestion ◽

Biogas Production ◽

Treatment Plant ◽

Anaerobic Sludge ◽

Content Increase ◽

Limited Information ◽

Dynamic Simulations ◽

Treatment Train ◽

Temperature Liquid ◽

The Impact

Abstract Upgrading conventional single-stage mesophilic anaerobic digestion to an advanced digestion technology can increase sludge stability, reduce pathogen content, increase biogas production, and also increase ammonia concentrations recycled back to the liquid treatment train. Limited information is available to assess whether the higher ammonia recycle loads from an anaerobic sludge digestion upgrade would lead to higher discharge effluent ammonia concentrations. Biowin, a commercially available wastewater treatment plant simulation package, was used to predict the effects of anaerobic digestion upgrades on the liquid train performance, especially effluent ammonia concentrations. A factorial analysis indicated that the influent total Kjeldahl nitrogen (TKN) and influent alkalinity each had a 50-fold larger influence on the effluent NH3 concentration than either the ambient temperature, liquid train SRT or anaerobic digestion efficiency. Dynamic simulations indicated that the diurnal variation in effluent NH3 concentration was 9 times higher than the increase due to higher digester VSR. Higher recycle NH3 loads caused by upgrades to advanced digestion techniques can likely be adequately managed by scheduling dewatering to coincide with periods of low influent TKN load and ensuring sufficient alkalinity for nitrification.

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Biochemical Methane Potential of Cork Boiling Wastewater at Different Inoculum to Substrate Ratios

Applied Sciences ◽

10.3390/app11073064 ◽

2021 ◽

Vol 11 (7) ◽

pp. 3064

Author(s):

Roberta Mota-Panizio ◽

Manuel Jesús Hermoso-Orzáez ◽

Luis Carmo-Calado ◽

Gonçalo Lourinho ◽

Paulo Sérgio Duque de Brito

Keyword(s):

Anaerobic Digestion ◽

Biogas Production ◽

Treatment Plant ◽

Organic Substrates ◽

Biochemical Methane Potential ◽

Volatile Solids ◽

Working Volume ◽

Methane Potential ◽

Bmp Test ◽

Cork Industry

The present study evaluates the digestion of cork boiling wastewater (CBW) through a biochemical methane potential (BMP) test. BMP assays were carried out with a working volume of 600 mL at a constant mesophilic temperature (35 °C). The experiment bottles contained CBW and inoculum (digested sludge from a wastewater treatment plant (WWTP)), with a ratio of inoculum/substrate (Ino/CBW) of 1:1 and 2:1 on the basis of volatile solids (VSs); the codigestion with food waste (FW) had a ratio of 2/0.7:0.3 (Ino/CBW:FW) and the codigestion with cow manure (CM) had a ratio of 2/0.5:0.5 (Ino/CBW:CM). Biogas and methane production was proportional to the inoculum substrate ratio (ISR) used. BMP tests have proved to be valuable for inferring the adequacy of anaerobic digestion to treat wastewater from the cork industry. The results indicate that the biomethane potential of CBWs for Ino/CBW ratios 1:1 and 2:1 is very low compared to other organic substrates. For the codigestion tests, the test with the Ino/CBW:CM ratio of 2/0.7:0.3 showed better biomethane yields, being in the expected values. This demonstrated that it is possible to perform the anaerobic digestion (AD) of CBW using a cosubstrate to increase biogas production and biomethane and to improve the quality of the final digestate.

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Mesophilic and Thermophilic Digestion of Thickened Waste Activated Sludge: A Comparative Study

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.113-116.450 ◽

2010 ◽

Vol 113-116 ◽

pp. 450-458 ◽

Cited By ~ 2

Author(s):

Yong Zhi Chi ◽

Yu You Li ◽

Min Ji ◽

Hong Qiang ◽

Heng Wei Deng ◽

...

Keyword(s):

Anaerobic Digestion ◽

Activated Sludge ◽

Municipal Wastewater ◽

Treatment Plant ◽

Methane Content ◽

Waste Activated Sludge ◽

Digested Sludge ◽

Anaerobic Digestion Process ◽

Digestion Process ◽

Significant Difference

This paper presents an experimental study over 204 days on anaerobic degradation of thickened waste activated sludge (TWAS) from a municipal wastewater treatment plant (WWTP). The experiments were conducted under thermophilic (55°C) and mesophilic (35°C) condition, respectively, by using the semi-continuous flow completely mixed reactors. The influent total solids (TS), hydraulic retention time (HRT) and chemical oxygen demand (COD) loading levels were around 4%, 30 days and 1.67 kg-CODCr•m-3•d-1 , respectively. During the opration period, the thermophilic anaerobic digestion process (TADP) and the mesophilic anaerobic digestion process (MADP) were stable and well-functioned without ammonia inhibition. Particulate organic matters reduction of TADP was superior to that of MADP. This result implies that TADP has higher sludge reduction efficiency than MADP. According to the simulated chemical formula of TWAS, C5.85H9.75O3.96N, and the stoichiometric equation, the methane content and the ammonia yield in the anaerobic process could be calculated, which were consistent with the experimental results. The methane yield of TADP was a little higher than that of MADP. The statistical mean values of methane content for TADP and MADP were 60.97% and 62.38%, respectively.According to paired t-test, there was a significant difference in methane content between TADP and MADP(α=0.01, n=62). Compared with the mesophilic digested sludge, the dewaterability of thermophilic digested sludge was lower.

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