Temperature Effects on Physiology of Biological Phosphorus Removal

Production of polyhydroxyalkanoates (PHAs) by an open mixed culture enriched in glycogen accumulating organisms (GAOs) under alternating anaerobic-aerobic conditions with acetate as carbon source was investigated. The culture exhibited a stable enrichment performance over the 450-day operating period with regards to phenotypic behavior and microbial community structure. Candidatus Competibacter phosphatis dominated the culture at between 54% and 70% of the bacterial biomass throughout the study, as determined by fluorescence in situ hybridization. In batch experiments under anaerobic conditions, PHA containing 3-hydroxybutyrate (3HB) and 27 mol-% 3-hydroxyvalerate (3HV) was accumulated up to 49% of cell dry weight utilizing the glycogen pool stored in the SBR cycle. Under aerobic and ammonia limited conditions, PHA comprising only 3HB was accumulated to 60% of cell dry weight. Glycogen was consumed during aerobic PHA accumulation as well as under anaerobic conditions, but with different stoichiometry. Under aerobic conditions 0.31 C-mol glycogen was consumed per consumed C-mol acetate compared to 0.99 under anaerobic conditions. Both the PHA biomass content and the specific PHA production rate obtained were similar to what is typically obtained using the more commonly applied aerobic dynamic feeding strategy.

Section: Enrichment Of Gaoscontrasting

confidence: 52%

The utilization of glycogen accumulating organisms for mixed culture production of polyhydroxyalkanoates

Bengtsson

2009

“…This observation was recorded in conjunction with a period of abnormally cold weather that brought the process temperature suddenly from 17 to below 148C. The sensitivity of the EBPR kinetics to short-term temperature transients is well documented in the literature (Brdjanovic et al, 1997). As can be observed from Figure 8, the MEBPR system demonstrated a much faster recovery (40 vs. 60 days) in activity, relative to the CEBPR system, likely caused by the ability of the membrane to retain all the organisms and by the slightly longer bioreactor SRT.…”

Section: Bio-p Failure 3 Andmentioning

confidence: 76%

Comparative study of biological nutrient removal (BNR) processes with sedimentation and membrane‐based separation

Monti

Hall

Dawson

et al. 2006

A membrane-enhanced biological phosphorus removal (MEBPR) process was operated in parallel with a conventional EBPR (CEBPR) process under challenging operating conditions to uncover fundamental differences in their ability to remove chemical oxygen demand (COD), nitrogen (N), and phosphorus (P) from municipal wastewater. Both systems exhibited the same potential to achieve excellent soluble-P removal when a favorable COD to P ratio was maintained in the influent. The MEBPR train generated a superior effluent quality when measured as total P. The CEBPR effluent contained significantly lower levels of nitrates due to the extra denitrification occurring in the sludge blanket of the secondary clarifier. The observed sludge yield in the MEBPR system was estimated to be between 0.23 and 0.28 g VSS/g COD, and this was 15% lower than the CEBPR sludge yield. When the influent volatile fatty acids (VFAs) became limiting, the CEBPR train exhibited better performance in the removal of soluble-P, due to the higher observed sludge yield and an overall greater denitrification activity that led to a more efficient use of VFAs in the anaerobic zone. After experiencing a severe deterioration of the biological P activity in both processes, the MEBPR train exhibited faster recovery than the CEBPR side. In this experimental work, it was demonstrated that an MEBPR process can sustain long-term satisfactory bio-P performance at HRTs as low as 7 h. However, the lower sludge yield and the reduced denitrification capacity are two important factors that impact the design of high rate membrane-assisted biological nutrient removal (BNR) processes.

“…It is still unknown whether the EBPR deterioration occurred because: (a) PAO are not able to adapt to higher temperature levels (>208C) giving GAO the chance to proliferate, (b) GAO have metabolic advantages over PAO at high temperatures, or (c) a combination of both previous causes. Brdjanovic et al (1997Brdjanovic et al ( , 1998a carried out a systematic study on an enriched PAO culture in order to understand the short-and long-term temperature effects on the EBPR process from 5 to 308C. According to their observations, the observed temperature dependencies at short-(a few hours) and long-term (weeks) were well described by applying the Arrhenius temperature coefficients calculated in that research.…”

Section: Introductionmentioning

confidence: 92%

Short‐term temperature effects on the anaerobic metabolism of glycogen accumulating organisms

López-Vázquez

Song

Hooijmans

et al. 2006

Self Cite

Proliferation of glycogen accumulating organisms (GAO) has been identified as a potential cause of enhanced biological phosphorus removal (EBPR) failure in wastewater treatment plants (WWTP). GAO compete for substrate with polyphosphate accumulating organisms (PAO) that are the microorganisms responsible for the phosphorus removal process. In the present article, the effects of temperature on the anaerobic metabolism of GAO were studied in a broad temperature range (from 10 to 40 degrees C). Additionally, maximum acetate uptake rate of PAO, between 20 and 40 degrees C, was also evaluated. It was found that GAO had clear advantages over PAO for substrate uptake at temperatures higher than 20 degrees C. Below 20 degrees C, maximum acetate uptake rates of both microorganisms were similar. However, lower maintenance requirements at temperature lower than 30 degrees C give PAO metabolic advantages in the PAO-GAO competition. Consequently, PAO could be considered to be psychrophilic microorganisms while GAO appear to be mesophilic. These findings contribute to understand the observed stability of the EBPR process in WWTP operated under cold weather conditions. They may also explain the proliferation of GAO in WWTP and thus, EBPR instability, observed in hot climate regions or when treating warm industrial effluents. It is suggested to take into account the observed temperature dependencies of PAO and GAO in order to extend the applicability of current activated sludge models to a wider temperature range.