Changes in process performance and microbial characteristics of retained sludge during low-temperature operation of an EGSB reactor

In this study, a lab scale EGSB reactor was operated for 400 days to investigate the influence of temperature-decrease on the microbial characteristic of retained sludge. The EGSB reactor was started-up at 15°C seeding with 20°C-grown granular sludge. The influent COD of synthetic wastewater was set at 0.6–0.8 gCOD/L. The process-temperature was stepwise reduced from 15°C to 5°C during 400 days operation. Decrease of temperature of the reactor from 15°C to 10°C caused the decline of COD removal efficiency. However, continuous operation of the EGSB reactor led the efficient treatment of wastewater (70% of COD removal, 50% of methane recovery) at 10°C. We confirmed that the both acetate-fed and hydrogen-fed methanogenic activities of retained sludge clearly increased under 15 to 20°C. Changes of microbial profiles of methanogenic bacteria were analyzed by 16S rDNA-targeted DGGE analysis and cloning. It shows that genus Methanospirillum as hydrogen-utilizing methanogen proliferated due to low temperature operation of the reactor. On the other hand, genus Methanosaeta presented in abundance as acetoclastic-methanogen throughout the experiment.

Download Full-text

Ammonia oxidizing bacterial community composition and process performance in wastewater treatment plants under low temperature conditions

Water Science & Technology ◽

10.2166/wst.2012.643 ◽

2012 ◽

Vol 65 (2) ◽

pp. 197-204 ◽

Cited By ~ 27

Author(s):

A. Rodriguez-Caballero ◽

S. Hallin ◽

C. Påhlson ◽

M. Odlare ◽

E. Dahlquist

Keyword(s):

Wastewater Treatment ◽

Low Temperature ◽

Removal Efficiency ◽

Wastewater Treatment Plants ◽

Bacterial Community Composition ◽

Ammonia Removal ◽

Ammonia Oxidizer ◽

Process Performance ◽

Temperature Conditions ◽

N Removal

Nitrification can be difficult to maintain at wastewater treatment plants (WWTPs) during cold periods resulting in disrupted nitrogen removal. The aim of this study was to relate nitrification process performance to abundance and composition of the ammonia oxidizer communities in two closely located municipal WWTPs in Sweden during an eight month period covering seasonal changes and low temperature conditions. Both facilities showed lower NH4+-N removal efficiency and nitrification rates as temperature decreased. However, one of the plants had a more stable nitrification rate and higher ammonia removal efficiency throughout the entire period. The differences in performance was related to a shift in the composition of the bacterial ammonia oxidizing community from a Nitrosomonas oligotropha-dominated community to a mixed community including also Nitrosomonas ureae-like ammonia oxidizers. This was likely a response to differences in NH4+-N and organic loading.

Download Full-text

Study on Low Temperature on SBR Process Performance

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.113-116.770 ◽

2010 ◽

Vol 113-116 ◽

pp. 770-774

Author(s):

Xing Bin Sun ◽

Zhao Chao Hou ◽

Jin Long Zuo

Keyword(s):

Water Quality ◽

Low Temperature ◽

The State ◽

Experimental Results ◽

Process Performance ◽

Temperature Influence ◽

Effluent Water ◽

Sludge Bulking ◽

Do Concentration ◽

Pollutants Removal

In order to investigate low-temperature influence on the SBR process and sludge bulking, the SBR process pollutants removal effect was studied with normal and low temperature. The experimental results showed that the effluent water quality was better with temperature 22~24°C and DO 2mg/L. During this period, sludge bulking did not happen and the SVI was stable for 30d at the range of 60~80mL/g. The sludge settlement became worse when the temperature sharply dropped to 13~15°C and DO concentration was unchanged, the SVI was sharply increased to 240~270mL/g from 60~80mL/g in several cycles, and it was in the state of sludge bulking for 60d. The system denitrification effect was almost lost and the nitrification effect had been seriously affected. When the temperature returned to normal, the nitrification effect was gradually improved. The effluent water was clear and the SVI returned gradually, but the SVI eventually maintained at 150mL/g without retune to previous range.

Download Full-text

Application of low temperature soaking liquid in combined freezing-based desalination processes in summer

Journal of Water Reuse and Desalination ◽

10.2166/wrd.2021.122 ◽

2021 ◽

Author(s):

Hui Yang ◽

Yuanfei Jiang ◽

Mengxiao Fu ◽

Rui Wang

Keyword(s):

Low Temperature ◽

Removal Efficiency ◽

Air Temperature ◽

Melting Time ◽

Process Performance ◽

Industrial Practice ◽

Soaking Time ◽

Yield Rate ◽

Cold Energy ◽

Made In

Abstract In our previous study, it was noticed that the combined freezing, soaking and centrifugal desalination (FSCD) process is unsuitable to be applied in summer, because very little pure ice can be produced when the temperature of raw seawater used as soaking liquid reaches 27 °C. Therefore, two main efforts on the process optimization were made in this paper. One is that low-temperature seawater was served as soaking liquid in all the experiments. In real industrial practice, the low-temperature soaking liquid can be obtained through melting pure ice products or recovering cold energy from cold concentrated brine. The effects of centrifugal parameters and soaking time on salt removal efficiency and ice yield rate were investigated. Second, the gravity-induced method was combined to form freezing, soaking, gravity-induced and centrifugal desalination (FSGCD) process for further improvement of the salt removal efficiency. The influence of melting time of gravity-induced process was studied by keeping the samples ambient with an air temperature of 30 °C. Finally, the performance among different processes was compared. Results showed that the salt removal efficiency of FSGCD process can reach up to 97.03%. The study is effectively helpful to improve the process performance of soaking treatment in summer application.

Download Full-text