Biological nutrient removal wastewater treatments and sewage sludge anaerobic mesophilic digestion performances

2002 ◽  
Vol 46 (10) ◽  
pp. 199-208 ◽  
Author(s):  
D. Bolzonella ◽  
L. Innocenti ◽  
F. Cecchi
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Economic Assessment ◽  
Gas Production ◽  
Anaerobic Digester ◽  
Biological Nutrient Removal ◽  
Energetic Balance ◽  
Mesophilic Digestion ◽  
The Difference ◽  
Energy Balances

The paper deals with the performances of the mesophilic anaerobic digestion treatment of sewage sludge from a full scale BNR process without primary settling (nominally 300,000 PE). A relation between the activated sludge observed yields, Yobs, and the anaerobic digester performance was preliminarily found: for values of Yobs of 0.25 kgVSS/kgCOD the anaerobic digester specific gas production showed the best performances (0.22 m3/kgVSfed). This has to be confirmed with wider future studies. It was also shown the level of sludge pre-thickening to be reached for the self-sustaining warming of the digester also in wintertime. According to the energetic balance and to a comparison with an aerobic stabilisation process, it was pointed out as when a co-generation unit for heat and energy production was introduced about 3.4 kWh/PE y of energy were produced in the anaerobic digestion process. On the other hand, 4.3 kWh/PE y were spent if an aerobic stabilisation process was applied. The economic assessment, carried out on the basis of the energy balances, showed that the anaerobic digestion is always economically advantageous if compared to aerobic stabilisation processes, also for small WWTPs. According to the energetic evaluations an environmental balance was assessed, in terms of CO2 emissions. The difference between anaerobic and aerobic processes was about 5.3 kgCO2/PE y in favour of anaerobic processes application.

Gasification as an optimum alternative for the sludge management

2011 ◽  
Vol 6 (4) ◽  
Author(s):  
C. Peregrina ◽  
J. M. Audic ◽  
P. Dauthuille
Keyword(s):  
Power Generation ◽  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Combined Heat And Power ◽  
Gas Production ◽  
Waste Reduction ◽  
Fluidised Bed ◽  
Sludge Management ◽  
Gas Cleaning ◽  
Cleaning System

Assimilate sludge to a fuel is not new. Sludge incineration and Combined Heat and Power (CHP) engines powered with sludge-derived anaerobic digestion gas (ADG) are operations widely used. However, they have a room of improvement to reach simultaneously a positive net power generation and a significant level of waste reduction and stabilization. Gasification has been used in other realms for the conversion of any negative-value carbon-based materials, that would otherwise be disposed as waste, to a gaseous product with a usable heating value for power generation . In fact, the produced gas, the so-called synthetic gas (or syngas), could be suitable for combined heat and power motors. Within this framework gasification could be seen as an optimum alternative for the sludge management that would allow the highest waste reduction yield (similar to incineration) with a high power generation. Although gasification remains a promising route for sewage sludge valorisation, campaigns of measurements show that is not a simple operation and there are still several technical issues to resolve before that gasification was considered to be fully applied in the sludge management. Fluidised bed was chosen by certain technology developers because it is an easy and well known process for solid combustion, and very suitable for non-conventional fuels. However, our tests showed a poor reliable process for gasification of sludge giving a low quality gas production with a significant amount of tars to be treated. The cleaning system that was proposed shows a very limited removal performance and difficulties to be operated. Within the sizes of more common WWTP, an alternative solution to the fluidised bed reactor would be the downdraft bed gasifier that was also audited. Most relevant data of this audit suggest that the technology is more adapted to the idea of sludge gasification presented in the beginning of this paper where a maximum waste reduction is achieved with a great electricity generation thanks to the use of a “good” quality syngas in a CHP engine. Audit show also that there is still some work to do in order to push sludge gasification to a more industrial stage. Regardless what solution would be preferred, the resulting gasification system would involve a more complex scenario compared to Anaerobic Digestion and Incineration, characterised by a thermal dryer and gasifier with a complete gas cleaning system. At the end, economics, reliability and mass and energy yields should be carefully analysed in order to set the place that gasification would play in the forthcoming processing of sewage sludge.

scholarly journals Plantwide modelling – anaerobic digestion of waste sludge from parent nutrient (N and P) removal systems

Water SA ◽  
2019 ◽  
Vol 45 (3 July) ◽  
Author(s):  
DS Ikumi ◽  
GA Ekama
Keyword(s):  
Anaerobic Digestion ◽  
Activated Sludge ◽  
Volatile Fatty Acids ◽  
Treatment Plant ◽  
Anaerobic Digester ◽  
Hydrolysis Rate ◽  
Biological Nutrient Removal ◽  
Biomass Hydrolysis ◽  
Behavioural Patterns ◽  
Anaerobic Zone

Wastewater treatment plant (WWTP) mathematical models are based on the behavioural patterns of microorganisms involved in the treatment process. These microorganisms are assumed incapable of thinking or planning but simply act according to the capabilities afforded to them by their surrounding conditions – hence different microorganisms pre-dominate different WWTP zones according to how well the conditions suit them. When waste activated sludge (WAS) from biological nutrient removal (BNR) activated sludge (AS) systems, containing phosphorus-accumulating organisms (PAOs), is fed to an anaerobic digester, there is a release of high quantities of metals, phosphorus (P) and nitrogen (N). The manner in which we model the release of these metals and nutrients significantly affects the accuracy of predicted anaerobic digestion (AD) outcomes. Previous studies of PAOs show that in the anaerobic zone of the AS system, they can form energy-rich poly3-hydroxybutyrate (PHB) at the expense of their aerobically generated polyphosphate (PP). Thus, it is expected that the PAOs containing PP sent into an anaerobic digester with volatile fatty acids (VFAs) present, would utilize their PP reserves as they would in the anaerobic zone of an AS process ending up with formation and storage of some PHB. Ultimately, all the stored products of the PAO get released, since there is no alternating aerobic environment to cater for their growth. Since it has been established that the PP release in the AD occurs much faster than the PAO biomass hydrolysis rate, it is modelled as a separate process. Steps are presented in the development of this PP release mass-balanced stoichiometries that occur with AD of PAOs. By comparing outcomes from these proposed stoichiometries against measured experimental data, it is noticed that better predictions are obtained with acetate uptake for PHB formation than when modelling the AD PP release to occur with PAO death and hydrolysis.

Pretreatment followed by anaerobic digestion of secondary sludge for reduction of sewage sludge volume

2013 ◽  
Vol 67 (11) ◽  
pp. 2527-2533 ◽  
Author(s):  
Naoki Abe ◽  
Yue-Qin Tang ◽  
Makoto Iwamura ◽  
Shigeru Morimura ◽  
Kenji Kida
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Thermal Treatment ◽  
Low Pressure ◽  
Gas Production ◽  
Wet Oxidation ◽  
Thermophilic Anaerobic Digestion ◽  
Sludge Pretreatment ◽  
Secondary Sludge ◽  
Digestion Efficiency

The influence of two pretreatment methods, thermal treatment and low-pressure wet oxidation, on the sludge digestion efficiency was examined. Batch thermophilic anaerobic digestion was used to evaluate the effectiveness of the pretreatment methods in terms of volatile suspended solids (VSS) digestion efficiency and gas production. The results showed that the gas production was not proportional to the VSS degradation efficiency of either thermal treatment or low-pressure wet oxidation. Low-pressure wet oxidation treatment at 150 °C along with 40% of the theoretical oxygen required to oxidize organic carbon gave the highest gas production and the VSS digestion efficiency of 77% at a VSS loading rate of 8 g l−1 d−1. The digestion efficiency was about 30% higher than that of thermophilic anaerobic digestion without sludge pretreatment. Sewage sludge could be treated effectively at a high VSS digestion efficiency with this pretreatment followed by thermophilic anaerobic digestion.

Overview of AD

2020 ◽  
Author(s):  
Jacob Joseph Lamb
Keyword(s):  
Fatty Acid ◽  
Anaerobic Digestion ◽  
Mathematical Models ◽  
Volatile Fatty Acid ◽  
Biological Process ◽  
Gas Production ◽  
Anaerobic Digester ◽  
Chemical Parameters ◽  
Reactor Configuration ◽  
Biogas Output

There are many methodologies for improving the biogas output from anaerobic digestion. These techniques include physical (e.g., gas production and feedstock parameters), reactor configuration and chemical parameters (e.g., pH and volatile fatty acid concentrations) within the digester can help to link particular functions and features of the process. Using this expanse of data, mathematical models can be used to understand and forecast the biological process within an anaerobic digester. Such models can then be further developed on a process and biological level to improve their ability to mimic the function of the reactor. This chapter will provide background into modelling and reactor configuration in order to obtain a digital twin of an anaerobic digester.

Enhancement of Sewage Sludge Anaerobic Digestibility by Sulfate Radical Pretreatment

2012 ◽  
Vol 518-523 ◽  
pp. 3358-3362 ◽  
Author(s):  
De Dong Sun ◽  
Hua Mei Liang ◽  
Chun Ma
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Removal Rate ◽  
Gas Production ◽  
Sulfate Radical ◽  
Methane Yield ◽  
Control Group ◽  
Pretreatment Condition ◽  
The Stability ◽  
Anaerobic Digestibility

The effect of sulfate radical(SO4−•) pretreatment on mesophilic anaerobic digestion of sewage sludge was investigated and compared with a control group. The results showed that pretreatment can effectively improve sludge anaerobic digestion performance. After sulfate radical pretreatment, the removal rate of TCOD during the digestion was increased by 11.5% , the cumulative gas production was increased by 44.9%.The VFA concentration increased in the supernatant after pretreatment, but the alkalinity was also increased at the same time, so as to ensure the stability of whole system. The highest methane yield under pretreatment condition was 0.27m3 CH4/kgVSremoval, 180.0% of the control. The results indicated that persulfate /K2S2O8 pretreatment could be an effective method for improving methane yield.

scholarly journals An experimental study on Bio-gas production by anaerobic digestion of RiceMill Wastewater (RMW)

2020 ◽  
Vol 23 (1) ◽  
pp. 35-42
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Gas Production ◽  
Anaerobic Digester ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Working Volume ◽  
Mesophilic Temperature ◽  
Rice Mill Wastewater

<p>With the rising interest for sustainable power source and ecological security, anaerobic digestion of biogas technology has attracted considerable attention within the scientific researchers. This paper proposes a new research achievement on biogas production from Rice Mill Wastewater (RMW) with the utilization of anaerobic digester. An anaerobic digester is maintained with RMW and distillery anaerobic sludge at mesophilic temperature condition for 15 days as stabilization mode. After attaining stabilization stage, studies continued to examine the effect of Organic Loading Rate (OLR) and Hydraulic Retention Time (HRT) on the mesophilic anaerobic digestion of RMW. The OLR of the anaerobic reactor increased stepwise from 0.25 to 3.91 Kg COD/m3/dayand HRT ranged from 1 to 32.0 days. The total chemical oxygen demand (TCOD) utilized was higher than 75% and the CH4 percentage of the biogas was 62.00-63.00% for the OLRs studied. The efficient working volume of the digester is preserved as 25% of distillery anaerobic sludge and 75% of rice mill wastewater, loaded at Mesophilic temperature conditions for study purpose. By changing the conditions of OLR and HRT, biogas production, methane yield and percentage of COD reduction is examined. An anaerobic sludge is utilized as a seeding material to biodegrade the organic pollutants present in the wastewater. It will enhance the biological treatment of effluent with anaerobic sludge in a continuous mode of activity.The result showed that the proposed analysis obtains more biogas production with reduced COD when compared with existing approaches.</p>

Effects of Thermal Pretreatment of Sewage Sludge on Anaerobic Digestion

1989 ◽  
Vol 21 (4-5) ◽  
pp. 97-108 ◽  
Author(s):  
J. Pinnekamp
Keyword(s):  
Anaerobic Digestion ◽  
Energy Balance ◽  
Sewage Sludge ◽  
Electricity Generation ◽  
Treatment Plant ◽  
Economic Advantage ◽  
Thermal Pretreatment ◽  
Sludge Treatment ◽  
Additional Advantage ◽  
Energy Balances

The study examines the constraints on thermal pretreatment of sludge at temperatures in excess of 100 °C and its effects on subsequent anaerobic digestion. The table below summarizes the maximum measured increase rates and the corresponding optimum pretreatment temperatures as a function of the type of sludge tested. The influence of the sludge type is considerable.Sludge TypeGas Yield without/with PretreatmentMaximum increase RateOptimum Pretreatment Temperaturel/kg VSinfl%°CDigested Sludge60.4223.0+ 269.2180Excess Sludge SLR = 0.03124.7278.1+ 123.0135Excess Sludge SLR = 0.15314.7546.7+ 73.7170Excess Sludge SLR = 2.00234.7334.2+ 42.4135Primary Sludge259.0326.6+ 20.3170Excess Sludge SLR = 0.60596.8600.0+ 0.5135 Calculation of detailed energy balances for various sludge treatment systems with and without thermal pretreatment revealed a clear economic advantage for thermal pretreatment. The excess heat for an overall system composed of thermal pretreatment, anaerobic stabilisation and digester-gas electricity generation is significantly higher than that for a system without pretreatment. Sludge pasteurisation represents an additional advantage of thermal pretreatment. In general, it may be stated that, provided certain conditions are satisfied, thermal pretreatment of sewage sludge prior to anaerobic stabilisation can positively affect the energy balance of the treatment plant.

scholarly journals Application of Hydrothermal Treatment to High Concentrated Sewage Sludge for Anaerobic Digestion Process

2013 ◽  
Vol 2 (3) ◽  
pp. 165-168 ◽  
Author(s):  
M. Orikawa ◽  
H. Kamahara ◽  
Y. Atsuta ◽  
H. Daimon
Keyword(s):  
Anaerobic Digestion ◽  
Sewage Sludge ◽  
Organic Carbon ◽  
Hydrothermal Treatment ◽  
Treatment Time ◽  
Gas Production ◽  
Total Carbon ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Sludge Concentration

Tomato and seaweed were produced by utilizing CO2 and heat discharged from power generation using biogas in Toyogawa biomass park, Japan. The biogas was obtained by anaerobic digestion with hydrothermal treatment. The hydrothermal treatment was applied to the high concentrated sewage sludge (22 % total solids (TS) dewatered sludge). The purpose of this study is to clarify the effect of hydrothermal treatment on the qualities of high concentrated sewage sludge, by analyzing particulate organic carbon (POC) and dissolved organic carbon (DOC). The hydrothermal treatment was investigated under 10-60 min of treatment time, 180-200 °C of temperature, 10-22 %-TS of sewage sludge concentration. The results showed that the DOC in each conditions increased through hydrothermal treatment. The highest DOC obtained was 67 % of total carbon concentration, when the temperature was 180 °C, treatment time was 60 min and sewage sludge concentration was 10 %-TS. Furthermore, the viscosity of treated sewage sludge was decreased by hydrothermal treatment. In batch anaerobic digestion test, methane gas production was confirmed. In addition, this study evaluated the energy balance of this system. Thus, the results of this study indicated that the possibility of application of hydrothermal treatment to high concentrated sewage sludge for anaerobic digestion process. Keywords: anaerobic reaction, hydrothermal treatment, sewage sludge, solubilization

Sludge minimization by disintegration at different wastewater treatment plants

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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