Anaerobic Digestion of Domestic Wastewater: The Role of Alkalinity in the Rate and Extent of Digestion

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
KM Foxon ◽  
CJ Brouckaert ◽  
CA Buckley
Keyword(s):  
Loading Rate ◽  
Domestic Wastewater ◽  
Microbial Consortia ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Kwazulu Natal ◽  
High Loading Rate ◽  
High Selection ◽  
The Stability ◽  
Anaerobic System

For an anaerobic baffled reactor (ABR) treating domestic wastewater, the major variables affecting the rate and extent of digestion are the organic loading/residence time, the upflow velocity and the pH/alkalinity characteristics of the wastewater. In this study, an ABR was operated at two different flow rates; in Phase A, a higher loading rate of 0.74 kgCOD/m3.d was employed, while in Phase B, the loading rate was reduced to 0.40 kgCOD/m3.d. At the higher organic loading rate, significantly higher solids accumulation rates per kgCOD treated were obtained, and it was estimated that only 30% of the influent COD was converted to CH4. At the lower loading rate the estimated conversion to methane was 60%. The most probable cause for the poor COD removal was failure of stable anaerobic microbial consortia to establish under the relatively high selection pressure experienced at the high loading rate, due to washout of anaerobic species. It was concluded that low wastewater alkalinity (240 mgCaCO3/l) characteristic of the KwaZulu-Natal East Coast region resulted in low compartment pH values and associated inhibition of microbial activity, causing slower digestion of organics, and greater washout, particularly of methanogenic organisms, at higher up-flow velocities. The implication was that critical value for up-flow velocity, above which washout of anaerobic species occurs, depends on the organic loading and the prevailing pH and alkalinity. This has implications for the stability of any anaerobic system, and the extent of treatment of the effluent, specifically, that low wastewater alkalinity has the potential to significantly affect reactor design in any anaerobic system.

Septic Tank Effluent Treatment by Subsurface Horizontal Flow Wetland

2010 ◽  
Vol 5 (4) ◽  
Author(s):  
Ellina S. Pandebesie ◽  
Ni Wayan Budi Arie
Keyword(s):  
Ground Water ◽  
Removal Efficiency ◽  
Open Space ◽  
Loading Rate ◽  
Domestic Wastewater ◽  
Septic Tank ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Septic Tank Effluent ◽  
Bod Removal

Domestic wastewater treatment in Indonesia, mostly treat by using septic tanks. The use of septic tanks preferred by the public because of the design, construction, and maintenance are easy and more economical for the system of domestic wastewater disposal. Effluent from the septic tank still contains BOD about 100 mg /l, COD about 250 mg/l and TSS about 100 mg /l. This effluent is still dangerous to public health and is not fulfill wastewater effluent standards yet. If there is open space available, extended treatment of septic tank effluent can be done by field infiltration. This open space must suitable for infiltration without contaminating the ground water or well water. In urban areas with ground water level is high such as Surabaya, water infiltrate into the ground causing the problem. Problems that arise are due to pollution of ground water and surface water contaminated by effluent from the septic tank. Because of these problems, it would require an alternative treatment of septic tank effluent. Appropriate technology would be a simple, economical, easy in operation and maintenance. One of wastewater processing that can be applied to the septic tank effluent is a constructed wetland system. Previous research carried out by using Cyperus papyrus plant with sand media in batch experiments showed satisfactory results. In this study, experiments conducted by using Cyperus papyrus plant with sand media with continuous flow in a horizontal subsurface flow wetland method. Wastewater flows with varying flow 90 ml /min and 180 ml /min. The objective of this research is to determine the ability of a horizontal subsurface flow wetland for treating septic tank effluent. The parameters analyzed were BOD and TSS. The results show the relation of organic loading rate with BOD removal efficiency. The highest organic loading rate of 0.051 kg BOD/m2.d on first day observations has BOD removal efficiency of 73.63% and the lowest organic loading rate of 0.029 kg BOD/m2.d with an efficiency of 70.82%. This shows that BOD removal efficiency is affected by organic loading rate. If BOD loading rate increase, it will decrease BOD removal efficiency. Organic loading rate recommended for domestic wastewater is 0.037-0.4 kg BOD5 /m2.d. Although in this study the organic loading rate exceeds the above recommendations, but efficiency is still good, above 70%.

Anaerobic digestion of Jatropha curcas L. press cake and effects of an iron-additive

2011 ◽  
Vol 29 (11) ◽  
pp. 1171-1176 ◽  
Author(s):  
Thomas Schmidt
Keyword(s):  
Anaerobic Digestion ◽  
Jatropha Curcas ◽  
Loading Rate ◽  
Press Cake ◽  
Biogas Production ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Biogas Yield ◽  
Jatropha Curcas L ◽  
The Stability

Oil production from Jatropha curcas L. seeds generates large amounts of Jatropha press cake (JPC) which can be utilized as a substrate for biogas production. The objective of this work was to investigate anaerobic mono-digestion of JPC and the effects of an iron additive (IA) on gas quality and process stability during the increase of the organic loading rate (OLR). With the increase of the OLR from 1.3 to 3.2 gVS L−1 day−1, the biogas yield in the reference reactor (RR) without IA decreased from 512 to 194 LN kgVS−1 and the CH4 concentration decreased from 69.3 to 44.4%. In the iron additive reactor (IAR), the biogas yield decreased from 530 to 462 LN kgVS−1 and the CH4 concentration decreased from 69.4 to 61.1%. The H2S concentration in the biogas was reduced by addition of the IA to values below 258 ppm in the IAR while H2S concentration in the RR increased and exceeded the detection limit of 5000 ppm. The acid capacity (AC) in the RR increased to more than 20 g L−1, indicating an accumulation of organic acids caused by process instability. AC values in the IAR remained stable at values below 5 g L−1. The results demonstrate that JPC can be used as sole substrate for anaerobic digestion up to an OLR of 2.4 gVS l−1 day−1. The addition of IA has effectively decreased the H2S content in the biogas and has improved the stability of the anaerobic process and the biogas quality.

Organic loading rate and food-to-microorganism ratio shape prokaryotic diversity in a demo-scale up-flow anaerobic sludge blanket reactor treating domestic wastewater

2013 ◽  
Vol 104 (6) ◽  
pp. 993-1003 ◽  
Author(s):  
Juliana Cardinali-Rezende ◽  
Juliana C. Araújo ◽  
Paulo G. S. Almeida ◽  
Carlos A. L. Chernicharo ◽  
José L. Sanz ◽  
...  
Keyword(s):  
Loading Rate ◽  
Scale Up ◽  
Domestic Wastewater ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Organic Loading ◽  
Prokaryotic Diversity ◽  
Anaerobic Sludge Blanket

scholarly journals Effects of Slurry Reflux on the Stability and Microbial Community Structure of Corn Stalk Anaerobic Digestion System

2021 ◽  
Author(s):  
ling zhao ◽  
yang gao ◽  
jiamin zhao ◽  
jiaixng sun ◽  
zhen wang ◽  
...  
Keyword(s):  
Microbial Community ◽  
Anaerobic Digestion ◽  
High Throughput Sequencing ◽  
Loading Rate ◽  
Ph Value ◽  
Community Diversity ◽  
System Stability ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
The Stability

Abstract Anaerobic digestion (AD) of corn stalks with slurry reflux and non-reflux was compared and evaluated，to clarify the effects of slurry reflux on AD. It was found that slurry reflux increased cumulative methane production by 45.80% and improved system stability. With the increase of organic loading rate (OLR), pH value and oxidation-reduction potential (ORP) of reflux group remained 7.16±0.23 and -338.71±9.22. High-throughput sequencing results showed that slurry reflux slowed down the decrease of microbial community diversity, and the richness of bacterial community increased by 9.16%. The dominant microorganisms were Bacteroidetes and Methanothrix in reflux group, the relative abundances were 32.41% and 41.75%, respectively. The increase of organic loading rate (OLR) altered the main methane-producing pathway of the AD system, and slurry reflux can delay this trend.

Anaerobic Treatment of Polyethylene Terephthalate (PET) Wastewater from Lab to Full Scale

1999 ◽  
Vol 40 (8) ◽  
pp. 229-236 ◽  
Author(s):  
F. Fdz-Polanco ◽  
M. D. Hidalgo ◽  
M. Fdz-Polanco ◽  
P. A. García Encina
Keyword(s):  
Polyethylene Terephthalate ◽  
Loading Rate ◽  
Treatment Plant ◽  
Textile Wastewater ◽  
Anaerobic Treatment ◽  
Cod Removal ◽  
Organic Loading Rate ◽  
Foam Formation ◽  
Organic Loading ◽  
Start Up

In the last decade Polyethylene Terephthalate (PET) production is growing. The wastewater of the “Catalana de Polimers” factory in Barcelona (Spain) has two main streams of similar flow rate, esterification (COD=30,000 mg/l) and textile (COD=4000 mg/l). In order to assess the anaerobic treatment viability, discontinuous and continuous experiments were carried out. Discontinuous biodegradability tests indicated that anaerobic biodegradability was 90 and 75% for esterification and textile wastewater. The textile stream revealed some tendency to foam formation and inhibitory effects. Nutrients, micronutrients and alkali limitations and dosage were determined. A continuous lab-scale UASB reactor was able to treat a mixture of 50% (v) esterification/textile wastewater with stable behaviour at organic loading rate larger than 12 g COD/l.d (0.3 g COD/g VSS.d) with COD removal efficiency greater than 90%. The start-up period was very short and the recuperation after overloading accidents was quite fast, in spite of the wash-out of solids. From the laboratory information an industrial treatment plant was designed and built, during the start-up period COD removal efficiencies larger than 90% and organic loading rate of 0.6 kg COD/kg VSS.d (5 kg COD/m3.d) have been reached.

Performance of an anaerobic baffled reactor (ABR) as a hydrolysis-acidogenesis unit in treating landfill leachate mixed with municipal sewage

2000 ◽  
Vol 42 (12) ◽  
pp. 115-121 ◽  
Author(s):  
B. Wang ◽  
Y. Shen
Keyword(s):  
Landfill Leachate ◽  
Loading Rate ◽  
Granular Sludge ◽  
Operational Performance ◽  
Municipal Sewage ◽  
Organic Loading Rate ◽  
Stable Operation ◽  
Organic Loading ◽  
Anaerobic Baffled Reactor ◽  
Biological Treatability

A study on the performance of an Anaerobic Baffled Reactor(ABR) as a hydrolysis-acidogenesis unit in treating the mixed wastewater of landfill leachate and municipal sewage in different volumetric ratios was carried out. The results showed that ABR substantially improved the biological treatability of the mixed wastewater by increasing its BOD5/COD ratio to 0.4–0.6 from the initial values of 0.15–0.3. The formation of bar-shaped granular sludge of 0.5–5 mm both in diameter and length with an SVI of 7.5–14.2 ml/g was observed in all compartments of the ABR when the organic loading rate reached 4.71 kgCOD/m3 · d. The effects of the ratios of NH4+-N/COD and COD/TP in mixed wastewater on the operational performance were also studied, from which it was found that a reasonable NH4+-N/COD ratio should be lower than 0.02, and the phosphorus supplement was needed when the volumetric ratio was higher than 4:6 for stable operation of ABR.

Impact of organic loading rate and reactor design on thermophilic anaerobic digestion of mixed supermarket waste

2021 ◽  
Vol 123 ◽  
pp. 52-59
Author(s):  
L. Megido ◽  
L. Negral ◽  
Y. Fernández-Nava ◽  
B. Suárez-Peña ◽  
P. Ormaechea ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Loading Rate ◽  
Reactor Design ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Thermophilic Anaerobic Digestion
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