Enhanced anaerobic digestion of waste activated sludge of low organic content in a novel digester

2015 ◽  
Vol 72 (6) ◽  
pp. 966-973 ◽  
Author(s):  
J. Wu ◽  
Y. Jiang ◽  
Z. P. Cao ◽  
Z. H. Li ◽  
Y. Y. Hu ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Suspended Solids ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Organic Content ◽  
Waste Activated Sludge ◽  
Continuous Stirred Tank Reactor ◽  
Internal Circulation ◽  
Solid Retention Time

A novel digester, termed an internal circulation anaerobic digester (ICAD), was developed to intensify sludge digestion. It consists of reaction zone, settling zone, thickening zone, riser and downcomer. Internal circulation in the digester is intensified by backflow biogas. The mesophilic ICAD treating thermal pretreated waste activated sludge with volatile suspended solids (VSS)/suspended solids (SS) of 0.45–0.49 was conducted in this study to reduce and stabilize the low organic content sludge. The results showed that the VSS removal rate and biogas rate reached 46.0% and 0.72 m3/kg VSSfed at hydraulic retention time (HRT) of 15 days. VSS/SS and soluble chemical oxygen demand (SCOD) of the effluent sludge ranged from 0.39 to 0.41 and 274 mg/L to 473 mg/L, respectively, under various HRTs from 10 to 27 days. The degradation ability of ICAD derived from the improved mass transfer by internal circulation and long solid retention time at short HRT is compared with continuous stirred tank reactor.

scholarly journals Volatile Fatty Acids and Biomethane Recovery from Thickened Waste Activated Sludge: Hydrothermal Pretreatment’s Retention Time Impact

Processes ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 1580
Author(s):  
Farokh laqa Kakar ◽  
Ahmed El Sayed ◽  
Neha Purohit ◽  
Elsayed Elbeshbishy
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Oxygen Demand ◽  
Hydrothermal Pretreatment ◽  
Waste Activated Sludge ◽  
Optimum Conditions ◽  
Pretreatment Temperature ◽  
Biomethane Production

The main objective of this study was to evaluate the hydrothermal pretreatment’s retention time influence on the volatile fatty acids and biomethane production from thickened waste activated sludge under mesophilic conditions. Six different retention times of 10, 20, 30, 40, 50, and 60 min were investigated while the hydrothermal pretreatment temperature was kept at 170 °C. The results showed that the chemical oxygen demand (COD) solubilization increased by increasing the hydrothermal pretreatment retention time up to 30 min and stabilized afterwards. The highest COD solubilization of 48% was observed for the sample pretreated at 170 °C for 30 min. Similarly, the sample pretreated at 170 °C for 30 min demonstrated the highest volatile fatty acids yield of 14.5 g COD/Lsubstrate added and a methane yield of 225 mL CH4/g TCODadded compared to 4.3 g COD/Lsubstrate added and 163 mL CH4/g TCODadded for the raw sample, respectively. The outcome of this study revealed that the optimum conditions for solubilization are not necessarily associated with the best fermentation and/or digestion performance.

Anaerobic treatment of complex wastewater and waste activated sludge – application of an upflow anaerobic solid removal (UASR) reactor for the removal and pre-hydrolysis of suspended COD

1997 ◽  
Vol 35 (10) ◽  
pp. 121-128 ◽  
Author(s):  
Grietje Zeeman ◽  
Wendy T. M. Sanders ◽  
Kaijun Y. Wang ◽  
Gatze Lettinga
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Anaerobic Treatment ◽  
Dairy Wastewater ◽  
Waste Activated Sludge ◽  
Solid Retention Time ◽  
Methanogenic Activity ◽  
Wastewater Systems ◽  
Co Precipitation ◽  
Solids Removal

The application of one phase anaerobic wastewater systems for the treatment of complex wastewaters containing high amounts of suspended solids or lipids is usually limited by accumulation of these compounds in the sludge bed. This accumulation reduces the solid retention time and methanogenic activity of the sludge. The aim of the presented research was to achieve removal of suspended solids or lipids in an Upflow Anaerobic Solids Removal reactor to make higher reactor loadings possible. Raw sewage, waste activated sludge and dairy wastewater were pre-treated in an UASR reactor. When treating the raw sewage at 17°C and 3.0 h HRT 65% of the suspended COD could be entrapped in the sludge bed. Treatment of 2 g COD/l waste activated sludge at 9.6h HRT and 20°C resulted in 98% removal of the suspended COD. In both cases only 6–7% acidification of the complex wastewater took place. Dairy wastewater consists of mainly dissolved and colloidal COD. The lipids are surrounded by a protein membrane. These proteins will precipitate at pH <4.6 resulting in co-precipitation of the lipids. At 20°C and 4.5h HRT 57% of the lactose present in the wastewater was acidified, resulting in a pH of 4.0 and 98% lipids removal. It was concluded that the UASR reactor can achieve very high removal efficiencies for CODss and lipids, yet the retained COD is just partly hydrolysed. The produced sludge can be post-digested at thermophilic or mesophilic conditions to produce methane gas.

Riboflavin boosts fermentative valeric acid generation from waste activated sludge

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3962-3969
Author(s):  
Binfang Shi ◽  
Jingang Huang ◽  
Zhenjiang Yin ◽  
Wei Han ◽  
Shanshan Qiu ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Acid Production ◽  
Volatile Fatty Acids ◽  
Suspended Solids ◽  
Oxygen Demand ◽  
Valeric Acid ◽  
Waste Activated Sludge ◽  
Acid Generation

Fermentative valeric acid production is a promising way to recycle valuable resources from waste activated sludge (WAS). This study investigated the feasibility of using riboflavin (RF) to enhance volatile fatty acids (VFAs) production, especially valeric acid production from WAS coupled with solid reduction. The results indicated that RF (0.5 mM) promoted the VFAs production by up to 41.0%. Valeric acid accounted for the most abundance within the VFAs components. When RF dosages were 0.05 to 5.0 mM in the WAS fermentation systems, the chemical oxygen demand fractions of valeric acid to the total VFAs were 41.0% to 62.8%, which were much higher than those using other chemical supplements. Moreover, RF enhanced the reduction of mixed liquor volatile suspended solids (MLVSS). When RF dosage was 0.2 mM, MLVSS reduction achieved a maximum at 47.4%, compared to that in the RF-free control (33.9% reduction). Riboflavin in this study was considered as a feasible chemical to enhance the fermentative valeric acid generation coupled to MLVSS reduction, realizing the reduction of solids and the reutilization of valuable resources from WAS.

Kinetic Modeling of Continuous Stirred Tank Reactor - Operating On Distillery Effluent

2020 ◽  
Author(s):  
Dhananjay Mohite ◽  
S.S. Salimath
Keyword(s):  
Volatile Fatty Acids ◽  
Removal Rate ◽  
Oxygen Demand ◽  
Organic Content ◽  
Stirred Tank ◽  
Distillery Effluent ◽  
Continuous Stirred Tank Reactor ◽  
Stirred Tank Reactor ◽  
Tank Reactor ◽  
Continuous Stirred Tank

Abstract To identify the viability and performance, distillery effluent having very high organic content was studied on continuous stirred tank reactor (CSTR). Under different organic loading rates (OLR), optimum conditions for highest chemical oxygen demand (COD) removal and biogas generation was found to be for OLR of 0.10 COD kg /d to 0.11 COD kg /d. Highest COD exertion efficiency was found to be around 73% for OLR of 9.166 kg COD/m3/d when hydraulic retention time (HRT) reduced from 15 to 14 days. Biogas generation was observed to be around 30 L/d with a conversion coefficient of 0.405 and 0.12 volatile fatty acids (VFA) to alkalinity ratio were recorded in this stage. Applying the modified Stovere Kincannon model to the reactor, the maximum removal rate constant (Umax) and saturation value constant (Kb) were found to be 17.123 kg/m3/day, and 33.471 kg/m3/day respectively. These records are predominantly significant, when operating the anaerobic biodigesters for treating the distillery effluent along with the production of biogas as an energy sources. CSTR can effectively be employed in treatment of this effluent however post bio-digestion effluent still contains considerable COD. To meet the pollution norms and standards it needs to be treated further. To understand the complex biological treatment process of this effluent further trials are required to be conducted.

scholarly journals Effect of pH and hydraulic retention time on volatile fatty acids production from real waste in dark fermentation process

2021 ◽  
Author(s):  
Muhammed Ali Abdullah Khan
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Biological Nutrient Removal ◽  
Waste Activated Sludge ◽  
Carbon Substrate ◽  
Primary Sludge

Waste-derived volatile fatty acids (VFAs) is an important carbon substrate for microorganisms engaged in the production of bioenergy, biodegradable plastics, and biological nutrient removal process. In this project, the generation and applications of waste-derived VFA were examined. Three solid wastes were used Primary sludge (PS), thickened waste activated sludge (TWAS) which were collected from Ashbridges Bay and source separated organics (SSO) that was collected from Disco Road facility. All the water quality analyses such as pH, TCOD, SCOD, TVFA, TSS, VSS, NH3 and, alkalinity were monitored. The results of this study showed that with increasing the Hydraulic retention time (HRT), the percentage of acidification increased. Furthermore, the results showed that alkaline pH was better than the acid pHs. Keywords: Total Volatile Fatty Acids, Soluble Chemical Oxygen Demand, Primary Sludge, Thickened Waste Activated Sludge, Source Separated Organics.

scholarly journals Effect of pH and hydraulic retention time on volatile fatty acids production from real waste in dark fermentation process

2021 ◽  
Author(s):  
Muhammed Ali Abdullah Khan
Keyword(s):  
Fatty Acids ◽  
Activated Sludge ◽  
Retention Time ◽  
Volatile Fatty Acids ◽  
Hydraulic Retention Time ◽  
Oxygen Demand ◽  
Biological Nutrient Removal ◽  
Waste Activated Sludge ◽  
Carbon Substrate ◽  
Primary Sludge

Waste-derived volatile fatty acids (VFAs) is an important carbon substrate for microorganisms engaged in the production of bioenergy, biodegradable plastics, and biological nutrient removal process. In this project, the generation and applications of waste-derived VFA were examined. Three solid wastes were used Primary sludge (PS), thickened waste activated sludge (TWAS) which were collected from Ashbridges Bay and source separated organics (SSO) that was collected from Disco Road facility. All the water quality analyses such as pH, TCOD, SCOD, TVFA, TSS, VSS, NH3 and, alkalinity were monitored. The results of this study showed that with increasing the Hydraulic retention time (HRT), the percentage of acidification increased. Furthermore, the results showed that alkaline pH was better than the acid pHs. Keywords: Total Volatile Fatty Acids, Soluble Chemical Oxygen Demand, Primary Sludge, Thickened Waste Activated Sludge, Source Separated Organics.

Recalcitrant organic matter removal from textile wastewater by an aerobic cell-immobilized pellet column

2013 ◽  
Vol 67 (9) ◽  
pp. 2124-2131 ◽  
Author(s):  
Moonil Kim ◽  
Dukkyu Han ◽  
Fenghao Cui ◽  
Wookeun Bae
Keyword(s):  
Activated Sludge ◽  
Retention Time ◽  
Cell Immobilization ◽  
Oxygen Demand ◽  
Textile Wastewater ◽  
Organic Content ◽  
Organic Loading Rate ◽  
Conventional Activated Sludge ◽  
Interactional Functions ◽  
Aerobic Cell

The treatment of textile wastewater is difficult because of its recalcitrant organic content. The biological removal of recalcitrant organics requires a long retention time for microbial growth. Activated sludge was immobilized in a polyethylene glycol pellet to allow for sufficient sludge retention time. The pellets were filled in an aerobic cell-immobilized pellet column (CIPC) reactor in order to investigate the removal of recalcitrant organics from textile wastewater. A textile wastewater effluent treated by a conventional activated sludge reactor was used as a target wastewater. The chemical oxygen demand (COD) removal efficiency of the aerobic CIPC reactor at various empty bed contact times was in the range of 42.2–60.5%. Half of the input COD was removed in the lower part (bottom 25% of the reactor volume) of the reactor when the organic loading rate was less than 1.5 kg COD/(m3•d). About 15–30% of the input COD was removed in the remaining part of the column reactor. The COD removed in this region was limitedly biodegradable. The biodegradation of recalcitrant organics could be carried out by the interactional functions of the various bacteria consortia by using a cell-immobilization process. The CIPC process could effectively treat textile wastewater using a short retention time because the microorganisms that degrade limitedly biodegradable organics were dominant in the reactor.

scholarly journals Enrich waste activated sludge digestibility via natural enzyme supplementation

2019 ◽  
Vol 83 ◽  
pp. 01012 ◽  
Author(s):  
Mohamed Elsamadony
Keyword(s):  
Activated Sludge ◽  
Chemical Oxygen Demand ◽  
Suspended Solids ◽  
Carica Papaya ◽  
Oxygen Demand ◽  
Total Suspended Solids ◽  
Enzyme Concentration ◽  
Waste Activated Sludge ◽  
Protein Molecules ◽  
Natural Enzyme

Upgrading of low biodegradable waste activated sludge (WAS) accomplished through supplement the hydrolysis step with natural enzymes source. Whereas, WAS is rich in particulate fractions in terms of total chemical oxygen demand (tCOD), total suspended solids (TSS) and volatile suspended solids (VSS) of 15.78, 14.92 and 12.15 g/L, respectively. Therefore, carica papaya enzymes were utilized to break down the peptide ponds in protein molecules such as papain and protease, as well as, lipases that catalyzed the degradation of lipids. The optimum mixture between papain, protease, and lipase enzymes was found to be 3: 1: 2 while the optimum enzyme concentration was 8%. This conditions was attributed to enhance the H2 productivity form WAS by 97.8%

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