scholarly journals Colloids, flocculation and carbon capture – a comprehensive plant-wide model

2018 ◽  
Vol 79 (1) ◽  
pp. 15-25 ◽  
Author(s):  
Hélène Hauduc ◽  
Ahmed Al-Omari ◽  
Bernhard Wett ◽  
Jose Jimenez ◽  
Haydee De Clippeleir ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Carbon Capture ◽  
Oxygen Demand ◽  
High Rate ◽  
Reactor Performance ◽  
Whole Plant ◽  
Solids Retention ◽  
Methane Potential ◽  
Intracellular Storage ◽  
Activated Sludge Systems

Abstract The implementation of carbon capture technologies such as high-rate activated sludge (HRAS) systems are gaining interests in water resource and recovery facilities (WRRFs) to minimize carbon oxidation and maximize organic carbon recovery and methane potential through biosorption of biodegradable organics into the biomass. Existing activated sludge models were developed to describe chemical oxygen demand (COD) removal in activated sludge systems operating at long solids retention times (SRT) (i.e. 3 days or longer) and fail to simulate the biological reactions at low SRT systems. A new model is developed to describe colloidal material removal and extracellular polymeric substance (EPS) generation, flocculation, and intracellular storage with the objective of extending the range of whole plant models to very short SRT systems. In this study, the model is tested against A-stage (adsorption) pilot reactor performance data and proved to match the COD and colloids removal at low SRT. The model was also tested on longer SRT systems where effluents do not contain much residual colloids, and digestion where colloids from decay processes are present.

Validating the Colloid model to optimise the design and operation of both moving-bed biofilm reactor and integrated fixed-film activated sludge systems

2014 ◽  
Vol 69 (7) ◽  
pp. 1552-1557 ◽  
Author(s):  
J. Albizuri ◽  
P. Grau ◽  
M. Christensson ◽  
L. Larrea
Keyword(s):  
Activated Sludge ◽  
Oxygen Demand ◽  
Biofilm Reactor ◽  
Nitrification Rate ◽  
Moving Bed Biofilm Reactor ◽  
Moving Bed ◽  
Fixed Film ◽  
Solids Retention ◽  
Lower Effect ◽  
Activated Sludge Systems

The paper presents a systematic study of simulations, using a previously calibrated Colloid model, from which it was found that: (i) for pure moving-bed biofilm reactor (MBBR) processes with tertiary nitrification conditions (no influent chemical oxygen demand (COD)), dissolved oxygen = 5 mg/L and residual NH4-N > 4 mgN/L, a nitrification rate of 1.2 gN/(m2d) was obtained at 10 °C. This rate decreases sharply when residual NH4-N is lower than 2 mgN/L, (ii) for MBBR systems with predenitrification–nitrification zones and COD in the influent (soluble and particulate), the nitrification rate (0.6 gN/(m2d)) is half of that in tertiary nitrification due to the effect of influent colloidal XS (particulate slowly biodegradable COD) and (iii) for integrated fixed-film activated sludge (IFAS) processes the nitrification rate in the biofilm (0.72 gN/(m2d)) is 20% higher than for the pure MBBR due to the lower effect of influent XS since it is adsorbed onto flocs. However, it is still 40% lower than the tertiary nitrification rate. In the IFAS, the fraction of the nitrification rate in suspension ranges from 10 to 70% when the aerobic solids retention time varies from 1.4 to 6 days.

scholarly journals Carbon capture for blackwater: chemical enhanced high-rate activated sludge process

2019 ◽  
Vol 80 (8) ◽  
pp. 1494-1504 ◽  
Author(s):  
Haixin Jiang ◽  
Xianchun Tang ◽  
Yexuan Wen ◽  
Yi He ◽  
Hongbin Chen
Keyword(s):  
Activated Sludge ◽  
Carbon Capture ◽  
Carbon Mineralization ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Appropriate Technology ◽  
Capture Efficiency ◽  
High Rate ◽  
Iron Salt ◽  
Carbon Recovery

Abstract Blackwater has more benefits for carbon recovery than conventional domestic wastewater. Carbon capture and up-concentration are crucial prerequisites for carbon recovery from blackwater, the same as domestic wastewater. Both chemical enhanced primary treatment (CEPT) and high-rate activated sludge (HRAS) processes have enormous potential to capture organics. However, single CEPT is subject to the disruption of influent sulfide, and single HRAS has insufficient flocculation capacity. As a result, their carbon capture efficiencies are low. By combining CEPT and HRAS with chemical enhanced high rate activated sludge (CEHRAS) process, the limitations of single CEPT and single HRAS offset each other. The carbon mineralization efficiency was significantly influenced by SRT rather than iron salt dosage. An iron dosage significantly decreased chemical oxygen demand (COD) lost in effluent. Both SRT and iron dosage had a significant influence on the carbon capture efficiency. However, HRT had no great impact on the organic mass balance. CEHRAS allowed up to 78.2% of carbon capture efficiency under the best conditions. The results of techno-economic analysis show that decreasing the iron salt dosage to 10 mg Fe/L could promise profiting for blackwater treatment. In conclusion, CEHRAS is a more appropriate technology to capture carbon in blackwater.

Nitrogen removal in activated sludge systems including denitrification in secondary clarifiers

1994 ◽  
Vol 30 (6) ◽  
pp. 101-111 ◽  
Author(s):  
H. Siegrist ◽  
W. Gujer
Keyword(s):  
Activated Sludge ◽  
Nitrogen Removal ◽  
Retention Time ◽  
Secondary Clarifier ◽  
Solids Retention Time ◽  
Solids Retention ◽  
Activated Sludge Systems

Denitrification in the secondary clarifier can contribute substantially to the nitrogen removal of activated sludge systems. This is illustrated on two treatment plants with different secondary clarifier systems. A model to estimate denitrification capacity and to design activated sludge systems for nitrogen removal is developed and verified with data from two treatment plants. The model includes denitrification in the secondary clarifier, wastewater composition (soluble readily biodegradable COD, particulate degradable COD), oxygen input into the anoxic volume, temperature, and solids retention time (SRT). The influence of aerated grit chambers and primary sedimentation on denitrification is discussed.

Investigation of sludge reduction and biogas generation in high-rate anaerobic side-stream reactors for wastewater treatment

2018 ◽  
Vol 4 (11) ◽  
pp. 1829-1838 ◽  
Author(s):  
Chul Park ◽  
Dong-Hyun Chon ◽  
Aaron Brennan ◽  
Heonseop Eom
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
High Rate ◽  
Sludge Reduction ◽  
Waste Sludge ◽  
Side Stream ◽  
Activated Sludge Systems ◽  
Sludge Production

Activated sludge systems incorporating a 2 day anaerobic side-stream reactor (ASSR) show significantly decreased waste sludge production.

Dynamic Modeling of Diffused Aeration Requirements for High-Rate Plug-Flow and Step-Feed Activated Sludge Systems

2010 ◽  
Vol 2010 (9) ◽  
pp. 7226-7245
Author(s):  
Peter Schauer ◽  
S. Murthy ◽  
S. Kharkhar ◽  
A. Shaw ◽  
C. deBarbadillo ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Dynamic Modeling ◽  
Plug Flow ◽  
High Rate ◽  
Activated Sludge Systems

Modeling of organic substrate transformation in the high-rate activated sludge process

2015 ◽  
Vol 71 (7) ◽  
pp. 971-979 ◽  
Author(s):  
Thomas Nogaj ◽  
Andrew Randall ◽  
Jose Jimenez ◽  
Imre Takacs ◽  
Charles Bott ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Extracellular Polymeric Substances ◽  
Oxygen Demand ◽  
Organic Substrate ◽  
High Rate ◽  
State Variables ◽  
Modified Model ◽  
Soluble Substrate ◽  
Substrate Model ◽  
Dual Substrate

This study describes the development of a modified activated sludge model No.1 framework to describe the organic substrate transformation in the high-rate activated sludge (HRAS) process. New process mechanisms for dual soluble substrate utilization, production of extracellular polymeric substances (EPS), absorption of soluble substrate (storage), and adsorption of colloidal substrate were included in the modified model. Data from two HRAS pilot plants were investigated to calibrate and to validate the proposed model for HRAS systems. A subdivision of readily biodegradable soluble substrate into a slow and fast fraction were included to allow accurate description of effluent soluble chemical oxygen demand (COD) in HRAS versus longer solids retention time (SRT) systems. The modified model incorporates production of EPS and storage polymers as part of the aerobic growth transformation process on the soluble substrate and transformation processes for flocculation of colloidal COD to particulate COD. The adsorbed organics are then converted through hydrolysis to the slowly biodegradable soluble fraction. Two soluble substrate models were evaluated during this study, i.e., the dual substrate and the diauxic models. Both models used two state variables for biodegradable soluble substrate (SBf and SBs) and a single biomass population. The A-stage pilot typically removed 63% of the soluble substrate (SB) at an SRT <0.13 d and 79% at SRT of 0.23 d. In comparison, the dual substrate model predicted 58% removal at the lower SRT and 78% at the higher SRT, with the diauxic model predicting 32% and 70% removals, respectively. Overall, the dual substrate model provided better results than the diauxic model and therefore it was adopted during this study. The dual substrate model successfully described the higher effluent soluble COD observed in the HRAS systems due to the partial removal of SBs, which is almost completely removed in higher SRT systems.

Methods for quantification of biosorption in high-rate activated sludge systems

2017 ◽  
Vol 128 ◽  
pp. 33-44 ◽  
Author(s):  
Arifur Rahman ◽  
Harold Yapuwa ◽  
Manel Garrido Baserba ◽  
Diego Rosso ◽  
Jose A. Jimenez ◽  
...  
Keyword(s):  
Activated Sludge ◽  
High Rate ◽  
Activated Sludge Systems

Sludge reduction and performance analysis of a modified sludge reduction process

2013 ◽  
Vol 69 (5) ◽  
pp. 934-940 ◽  
Author(s):  
Zhen Zhou ◽  
Weimin Qiao ◽  
Can Xing ◽  
Yingjun Wang ◽  
Chunying Wang ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Nitrogen Concentration ◽  
Oxygen Demand ◽  
Reduction Process ◽  
Ammonium Nitrogen ◽  
Aeration Tank ◽  
Sludge Reduction ◽  
Oxidation Reduction ◽  
Solids Retention ◽  
And Performance

A modified sludge process reduction activated sludge (SPRAS) technology was developed by inserting a sludge process reduction (SPR) module, composed of an aeration tank and a settler, before the activated sludge system was proposed in this study. Compared with the anaerobic/anoxic/aerobic (AAO) process, the SPRAS resulted in a remarkable decrease in sludge production by 76.6%; sludge decay owing to lengthy solids retention time (about 121.5 d) could be the major cause. During the 217-day operation, the oxidation-reduction potential (ORP) (from 54 to −198 mV) and pH (from 7.8 to 5.0) at the bottom of the SPR settler gradually decreased, and low ORP and pH were in favor of sludge reduction in the SPRAS system. The insertion of the SPR module improved the removal efficiencies of suspended solids, chemical oxygen demand and ammonium nitrogen, and total nitrogen concentration in the effluent was reduced from 23.89 ± 4.82 to 14.16 ± 3.98 mg/L by 50% influent bypassing the SPR module. These results indicated that the SPRAS process could produce much less excess sludge and guarantee better effluent quality than the AAO process.

scholarly journals Design and assessment of species-level qPCR primers targeting comammox

2018 ◽  
Author(s):  
Natalie Keene-Beach ◽  
Daniel R. Noguera
Keyword(s):  
Activated Sludge ◽  
Pcr Primers ◽  
Species Level ◽  
Minor Role ◽  
Ammonium Oxidation ◽  
Candidate Species ◽  
Solids Retention ◽  
A Minor ◽  
Activated Sludge Systems ◽  
Low Do

AbstractPublished PCR primers targeting the ammonia monooxygenase gene (amoA) were applied to samples from activated sludge systems operated with low dissolved oxygen (DO) to quantify total and clade-levelNitrospirathat perform complete ammonium oxidation (comammox); however, we found these existing primers resulted in significant artifact-associated non-target amplification. This not only overestimated comammoxamoAcopies but also resulted in numerous false positive detections in the environmental samples tested, as confirmed by gel electrophoresis. Therefore, to more accurately quantify known comammox, we designed specific and sensitive primers targeting three candidate species:Candidatus(Ca.) Nitrospira nitrosa,Ca.N. inopinata, andCa.N. nitrificans. The primers were tested withamoAtemplates of these candidate species, and used to quantify comammox at the species level in low DO activated sludge systems. We found that comammox related toCa.N. nitrosa were present and abundant in the majority of samples from low DO bioreactors and were not detected in samples from a high DO system. In addition, the greatest abundance ofCa.N. nitrosa was found in bioreactors operated with a long solids retention time.Ca.N. inopinata andCa.N. nitrificans were only detected sporadically in these samples, indicating a minor role of these comammox in nitrification under low DO conditions.Abstract art

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