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Recent Advancement and Combination of Different Molecular Tools and Techniques for Applications in Wastewater Treatment
Published in Maulin P. Shah, Wastewater Treatment, 2022
Ritwija Bhattacharya, Indraneel Rakshit, Aniruddha Mukhopadhyay, Pritha Bhattacharjee
The activated sludge system should comprise well-settling properties to separate sludge from the treated wastewater. Settling problems are caused due to bulking and foaming, which occur as a result of the excess growth of the filamentous bacteria. Stable foam formation takes place due to the presence of a high amount of filaments with a hydrophobic cell surface. Poor settling properties were reported in case of flocs containing a high amount of filaments. Bulking and foaming of sludge create trouble in the treatment plant and are a risk to public health as well. The filamentous microbial communities are comprised of a huge number of phylogenetically and physiologically different bacteria that are uncultured and not well characterized, although, the molecular techniques have helped to understand the bacterial composition and ecophysiology compared with the traditional morphology-based studies. Moreover, recent studies have reported the in situ uptake of organic compounds by various filamentous species. The studies gave an idea of the versatility and diversity of filamentous species, which would help to counter the mass proliferation. Cultivation-dependent and independent techniques extensively reported the activity of filamentous Microthrix parvicella as responsible for sludge bulking and foaming. The studies found that M. parvicella can utilize a wide range of organic substrates starting from simple molecules like acetic acid to complex substrates like long-chain fatty acids. As the simpler molecules were already consumed by other competing bacteria, uptake of larger molecules by M. parvicella has been observed mostly as this bacterium has a more hydrophobic cell surface compared with other bacteria of activated sludge, which helps in the process of lipid uptake. Adding polyaluminum chloride to the water affected surface lipid lipases and their ability to metabolize lipids and partially suppressed the growth of this bacterium (Wagner et al. 2002; Daims, Taylor and Wagner 2006).
SBR treatment of tank truck cleaning wastewater: sludge characteristics, chemical and ecotoxicological effluent quality
Published in Environmental Technology, 2018
Michel Caluwé, Thomas Dobbeleers, Dominique Daens, Luc Geuens, Ronny Blust, Jan Dries
The feeding pattern in a CAS system is widely known to be sensitive for the development of poor settling characteristics and filamentous bulking sludge [12–14]. Houtmeyers et al. [15] operated lab-scale reactors under regimes of continuous and intermittent feeding of substrate (glucose as main carbon source). Continuously fed systems rapidly resulted in the development of filamentous bacteria and bulking of the sludge. Intermittently fed systems, on the other hand, did form good settling sludge. The same results were obtained by Verachtert et al. [16] by using nutrient broth, acetate and starch. Van den Eynde et al. [17] confirmed this with brewery, petrochemical and dairy wastewater. The same findings were also observed by Caluwé et al. [18] during the treatment of tank truck cleaning (TTC) wastewater. Ciğgin et al. [19], Cubas et al. [20] and Martins et al. [21] investigated the influence of the feeding pattern during the treatment of starch, bactopeptone and acetate, respectively. The shorter the feeding period, the better the settling characteristics. As a general conclusion, it was stated that a feast/famine regime in an SBR supresses the development of filaments and stimulates the growth of floc-forming bacteria.
Energy saving control strategies for Haliscomenobacter hydrossis filamentous sludge bulking in the A/O process treating real low carbon/nitrogen domestic wastewater
Published in Environmental Technology, 2018
Erlong Jiao, Chundi Gao, Renfei Li, Ye Tian, Yongzhen Peng
In this study, the dominant filamentous bacteria in the bulking process treating real low C/N domestic wastewater were observed by using fluorescent in situ hybridization (FISH) [28]. To restrain the H. hydrossis, corresponding strategies with low energy cost were investigated by increasing the compartment numbers and DO in aerobic zones. Consequently, the H. hydrossis filamentous sludge bulking was controlled, and the sludge settleability and effluent quality also improved. Meanwhile, energy was saved by adjusting the DO concentration. Finally, the method provided an economical, simple and longstanding operation condition for WWTP.
Low sediment redox promotes cyanobacteria blooms across a trophic range: implications for management
Published in Lake and Reservoir Management, 2021
Lewis A. Molot, Sherry L. Schiff, Jason J. Venkiteswaran, Helen M. Baulch, Scott N. Higgins, Arthur Zastepa, Mark J. Verschoor, Daniel Walters
Harmful algal blooms, especially those consisting of filamentous and colonial cyanobacteria (cHABs), are a hallmark characteristic of eutrophic (nutrient-enriched) waters. cHABs produce numerous toxins that affect environmental health and public safety, and taste and odor compounds that alter the quality of drinking water supplies (Watson et al. 2008). Hence, mitigating cHABs remains a high management priority, especially as cHAB incidence has been increasing in eutrophic as well as oligotrophic lakes (Paerl and Huisman 2009, Winter et al. 2011, Scavia et al. 2014).