anaerobic digestion process Articles
-
An asymptotic observer-based monitoring scheme for a class of plug flow reactors
In this paper a monitoring tool is designed for a class of plug flow reactors whose mathematical model is described by a set of first-order partial differential equations with different coefficients in the convective terms. The infinite dimensional structure of such a tool is derived according to the methodology established in the design of the well-known asymptotic observer. As a consequence, it ...
-
The Anaerobic Digestion of Bio-Waste in Developing Countries
The anaerobic digestion process is typically used as a means of waste disposal or energy production. Anaerobic digestion of bio-waste in developing countries is extremely beneficial as it doesn’t just generate clean and safe energy, it also contributes towards other economic development issues and has considerable environmental benefits. In this article we will explore the many benefits of the ...
-
Use of real-time PCR with propidium monoazide for enumeration of viable Escherichia coli in anaerobic digestion
A combination of propidium monoazide (PMA) with real-time quantitative polymerase chain reaction (PMA-qPCR) was optimized to enumerate only viable Escherichia coli in anaerobic digestion processes. Repeating the PMA treatment twice and a final concentration of 100 μM resulted in an effective exclusion of DNA from heat-treated E. coli cells. In three anaerobic digestion processes, real-time ...
-
A review: factors affecting excess sludge anaerobic digestion for volatile fatty acids production
This paper presents a review of methods that improve the production of volatile fatty acids (VFA) from excess sludge during the anaerobic digestion process. These methods are mainly divided into two approaches. The first approach is located in the pre-treatment methods, which change the properties of the substrates, such as thermal pre-treatment, alkaline pre-treatment, microwave pre-treatment ...
-
Bioconversion of restaurant waste into Polyhydroxybutyrate (PHB) by recombinant E. coli through anaerobic digestion
The effect of temperature (30°C, 37°C, uncontrolled) and initial pH adjustment at pH 7 in the anaerobic digestion process was investigated to enhance the production of organic acids from restaurant waste. The highest organic acid level obtained was 39.6 g/L on the fifth day of fermentation conducted at 30°C and initial pH 7. The acids produced corresponded to 39.4% of the yield based ...
-
The effect of mixing conditions on anaerobic digester performance
The basic principle of aerobic wastewater treatment is the conversion of some parts of organic matters to biomass and this causes production of excessive sludge in aerobic processes. This excessive sludge is withdrawn from time to time to prevent accumulation of biomass in aeration basin. In most cases, this sludge requires the stabilization before the dewatering and disposal. Different processes ...
By ORBIT e.V.
-
Accelerated anaerobic release of K, Mg and P from surplus activated sludge for element recovery and struvite formation inhibition
Accelerated release of potassium (K), magnesium (Mg) and phosphorus (P) from surplus activated sludge (SAS) was investigated to develop a new system for the recovery of the elements. Anaerobic cultivation of SAS during 24 h released 78% of K and about 50% of Mg and P from SAS more effectively compared to aerobic cultivation (K: 40%, Mg: 15%, P: 15%). Furthermore, the addition of sodium ...
-
Start-up of a decentralized pilot plant for the anaerobic treatment of domestic wastewater
This paper is about the set-up and start-up of a decentralized anaerobic pilot plant for producing domestic service water from domestic wastewater. The plant consists of a two-stage anaerobic digestion process for degrading organic matter and a third-stage for ammonium removal using the Anammox process. Each reactor was started independently with synthetic wastewater of stage-specific ...
-
The effect of iron and aluminium for phosphorus removal on anaerobic digestion and organic sulfur generation
The addition of iron or aluminium into activated sludge basins for phosphorus removal is likely to impact both the efficiency of the anaerobic digestion process and the generation of odor-causing compounds following digestion and dewatering. In this study, the impact of iron and aluminium addition on digestion and odor-causing compounds was investigated by using batch digestion of combined ...
-
The effect of different mesophilic temperatures during anaerobic digestion of sludge on the overall performance of a WWTP in Sweden
This project was initiated to evaluate the effect of alternative process temperatures to 38 °C at the anaerobic digestion step in a Swedish wastewater treatment plant (WWTP) treating mixed sludge. The efficiency of the different temperatures was evaluated with respect to biogas production, volume of sludge produced and nutrient content in the reject water to find the optimum temperature for ...
-
Determination of greenhouse gas emission reductions from sewage sludge anaerobic digestion in China
Sewage sludge is a considerable source of greenhouse gas (GHG) emission in the field of organic solid waste treatment and disposal. In this case study, total GHG emissions from sludge anaerobic digestion, including direct and indirect emissions as well as replaceable emission reduction due to biogas being reused instead of natural gas, were quantified respectively. The results indicated that ...
-
Anaerobic co-digestion of municipal organic wastes and pre-treatment to enhance biogas production from waste
Co-digestion and pre-treatment have been recognized as effective, low-cost and commercially viable approaches to reduce anaerobic digestion process limitations and improve biogas yields. In our previous batch-scale study, fat, oil, and grease (FOG) was investigated as a suitable potential co-substrate, and thermo-chemical pre-treatment (TCPT) at pH = 10 and 55 °C improved CH4 ...
-
Innovative approach to centrate nitrification accomplishes multiple goals: nitrogen removal and odour control
In 2001, the City of Phoenix, Arizona (USA) committed to the conversion of the existing high-rate anaerobic digestion process at the 8.9 m3/s 91st Avenue Wastewater Treatment Plant (WWTP) to a multi-phase process (acid/methane, mesophilic/thermophilic) to optimise existing digestion capacity and achieve Class A biosolids. The improved solids reduction is anticipated to double the ammonia load in ...
-
Methane conversion efficiency as a simple control parameter for an anaerobic digester at high loading rates
The anaerobic digestion process is globally applied to the treatment of highly concentrated wastes such as industrial and rural effluents, and sewage sludge. However, it is known to be relatively unstable. When loaded with high concentrations of organic material, unwanted volatile fatty acids (VFA) are often produced rather than methane (CH4) gas which can lead to digester acidification and ...
-
Combination of batch experiments with continuous reactor data for ADM1 calibration: application to anaerobic digestion of pig slurry
Modelling anaerobic digestion processes is a key aspect of studying and optimizing digesters and related waste streams. However, for the satisfactory prediction of biogas production and effluent characteristics, some parameters have to be calibrated according to the characteristics of the substrates. This article describes a calibration procedure for the IWA ‘Anaerobic Digestion Model no. 1’ ...
-
Thermophilic two-phase anaerobic digestion of source-sorted organic fraction of municipal solid waste for bio-hythane production: effect of recirculation sludge on process stability and microbiology over a long-term pilot-scale experience
A two-stage thermophilic anaerobic digestion process for the concurrent production of hydrogen and methane through the treatment of the source-sorted organic fraction of municipal solid waste was carried out over a long-term pilot scale experience. Two continuously stirred tank reactors were operated for about 1 year. The results showed that stable production of bio-hythane without inoculum ...
-
Use of an elemental balance over primary and secondary anaerobic digestion of sewage sludge to determine its carbon impact
This paper details how a mass balance, which was conducted for all of United Utilities’ anaerobic digestion plants, was used to calculate emission factors for various types of anaerobic digestion processes to enable calculation their carbon footprint. The mass balance showed average volatile solids destruction rates of 45% and 11% over primary and secondary digestion respectively. The calculated ...
-
Two-phase thermophilic anaerobic digestion process for biohythane production treating biowaste: preliminary results
This paper deals with the optimization of a two-phase anaerobic process treating biowaste for hydrogen and methane production. Neither physical nor chemical pre-treatments were used to optimize the process. The work was carried out at pilot scale, using two CSTRs (200 and 380 L working volume respectively) both maintained at thermophilic temperature (55 °C) and fed semi-continuously with ...
-
A modified anaerobic digestion process with chemical sludge pre-treatment and its modelling
Activated Sludge Models (ASMs) assume an unbiodegradable organic particulate fraction in the activated sludge, which is derived from the decay of active microorganisms in the sludge and/or introduced from wastewater. In this study, a seasonal change of such activated sludge constituents in a municipal wastewater treatment plant was monitored for 1.5 years. The chemical oxygen demand ratio of ...
-
Lab-scaled digestibility study of wastewater sludge treated by thermal hydrolysis
ABSTRACT High-solids mesophilic anaerobic digestion (HS-MAD) processes employing thermal hydrolytic pretreatment (THP) have gained much interest in recent years; primarily because they have been shown to produce Class A biosolids in accordance with EPA 503 regulations, but also because they represent an economical approach to the maximization of available anaerobic digester volume. The ...
Need help finding the right suppliers? Try XPRT Sourcing. Let the XPRTs do the work for you