China
Africa
Explore chapters and articles related to this topic
Biological Waste Treatment
Published in Syed R. Qasim, Wastewater Treatment Plants, 2017
Although sludge bulking is a part of an operational problem, this topic is briefly covered here because solids separation is an integral part of process design. Sludge bulking is the rising of sludge, poor settling, or foaming. The main causes of sludge bulking are (1) characteristics of wastewater, (2) design limitations, and (3) plant operation. Fluctuations in flow and strength, pH, temperature, nutrients, and nature of wastes are related to wastewater characteristics. The design limitations may include an insufficient capacity of aeration, mixing, and return sludge. The plant operation factors constitute low DO, nutrient limitations, low F/M ratio, excessive aeration, and Nocardia growth. Sludge bulking, troubleshooting and control measures are covered in the operation and maintenance section of this chapter (Sec. 13-12).
Optimal control of anoxic selector based on activated sludge with different phosphorus removal ability
Published in Ai Sheng, Energy, Environment and Green Building Materials, 2015
The activated sludge process is widely applied in wastewater treatment plant, but it is usually troubled by sludge bulking. Most sludge bulking is induced by filamentous bacteria over-proliferation compared with floc-forming bacteria (Paolo et al, 2000). Till date, many methods such as adding oxidants or coagulants have been established to control filamentous bulking, but it is prone to recur when agents are finished. Otherwise, the cost of agents is expensive (Alejandro et al, 2003. Agridiotis et al, 2007). Recently, selector has become the promoted strategy to enhance sludge settleability (aerobic selector, anoxic selector and anaerobic selector) (Wu et al, 2003). As the discharge standard for nutrients, which are the major cause of eutrophication, is stricter than ever before (Auvray et al, 2006), the anoxic selector own nutrient removal ability is becoming more popular. Although many efforts have been made to optimize anoxic selector operation, there are still reports showing failure events in controlling sludge bulking (Eikelboom, 1998.).
Secondary Treatment
Published in David H.F. Liu, Béla G. Lipták, Wastewater Treatment, 2020
Major operational problems of the activated-sludge process are caused by bulking sludge, rising sludge, and Nocardia foam (Metcalf and Eddy, Inc. 1991). A bulking sludge has poor settleability and comparability and is usually caused by excessive growth of filamentous microorganisms. Factors such as waste characteristics and composition, nutrient contents, pH, temperature, and oxygen availability can cause sludge bulking. The absence of certain components in the wastewater such as nitrogen, phosphorus, and trace elements can lead to the development of a bulking sludge. This absence is critical when industrial wastes are mixed with municipal wastewater for combined treatment.
Microbial community composition in different carbon source types of biofilm A/O-MBR systems with complete sludge retention
Published in Environmental Technology, 2021
Adoonsook Dome, Chia-Yuan Chang, Wongrueng Aunnop, Pumas Chayakorn
The proportion of Chloroflexi ranged from 2.54–2.96% in the sludge biomass samples, and it was higher than that in PUS-biofilm samples (1.66–2.05%). For the different carbon sources, the smallest proportion of Chloroflexi was observed in the glucose feed system. However, they accounted for the largest proportion in the acetate feed system, while the proportion was lower in the propionate feed system. Chloroflexi, a group of filamentous bacteria generally observed in wastewater treatment plants, is crucial in the MBR system [37]. The growth of filamentous bacteria is also the main cause of sludge bulking in activated sludge. Sludge bulking is believed to be one of the causal agents in membrane fouling because filamentous bacteria can easily become attached to the membrane surface due to EPS production, lowering zeta potential, and producing higher values of hydrophobicity in the sludge floc [38]. Chudoba [39] indicated that long SRT favoured filamentous growth because of their low specific growth rates. Therefore, the higher abundance of filamentous bacteria in this study seemed to be caused by a very long SRT and may be one of the main reasons for the severe fouling found in this study.