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Access type: UnknownAuthor: search.filters.author.Khanthongthip, Passkorn

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    The Structure of the Cannibal Sludge flocs generated under the fast and the slow feed conditions and their Digestibility
    (2024-06-01)
    Khanthongthip, Passkorn
    ;
    Novak, John T.
    An activated sludge system that incorporates a sidestream anaerobic bioreactor, called the Cannibal process, generated about 60 % less solids than conventional activated sludge without any negative effects on the effluent quality. In addition, operating the Cannibal process with different feeding patterns can result in different system performance. When the feed is provided to the Cannibal system over a period of 5 minutes (fast feed), the system generates less solid than the Cannibal system fed over a period of 4 hours (slow feed). In this study, the cation exchange resin (CER) and sulfide addition procedures were utilized to extract the Cannibal sludge flocs generated under the fast and the slow feed conditions to gain a fundamental insight on the structure and their components of those flocs. In addition, the fast and the slow feed Cannibal sludge was anaerobically and aerobically digested to evaluate the effect of feeding patterns on their digestibility. It was found that the readily biodegradable (1 kDa.) CER and sulfide extracted protein is larger in the flocs from the fast feed than the slow feed Cannibal system. When these two different types of flocs were anaerobically digested, the major fractions to be degraded were the sulfide extractable proteins. It was also found that the proteins in the fast feed Cannibal sludge flocs were degraded more than that in the slow feed Cannibal sludge flocs under anaerobic conditions. Consequently, it can be proposed that the influence of the high substrate pressure (fast feed) is to generate larger readily biodegradable proteins in the fast feed than the slow feed Cannibal sludge flocs. Because the 1 kDa. sulfide extracted proteins released from the fast feed Cannibal sludge floc are more biodegradable than that from the slow feed Cannibal sludge under anaerobic environment, it can be thought that the 1 kDa. proteins generated under the fast feed condition may consist of either many simple amino acids that are easily degradable or amino acids that microorganisms cannot produce but need to consume for their survival.
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    Generation and fate of volatile organic sulfur compounds during anaerobic digestion of waste activated sludge
    (2021-01-01)
    Khanthongthip, Passkorn
    ;
    Yagci, Nevin
    ;
    Orhon, Derin
    ;
    Novak, John
    This study investigates the generation and fate of volatile organic sulfur compounds (VOSCs) during biodegradation of waste activated sludge under anaerobic conditions. Experiments involved the operation of laboratory-scale anaerobic digesters at a solid retention time of 20 d. Concentration profiles of methanethiol, dimethyl sulfide (DMS), dimethyl disulfide, and hydrogen sulfide were monitored. Methanethiol (MT) and DMS are the main organic sulfur compounds exhibiting con-secutive increase/decline phases. In the second step, aliquots taken from bioreactors were supple-mented with two sulfur-containing amino acids, cysteine, and methionine. The results suggest that the biodegradation of the two sulfur-containing proteins are the primary source of hydrogen sulfide, methanethiol, and DMS generation. Finally, ethyl-2-butynote was added to aliquots taken from the bioreactors to explore the role of methanogenic activity. Methane production is stopped, and result-ing MT and DMS profiles are no longer included as a declining phase. The results suggest that sulfur amino acids are a potential primary source for the formation of MT and DMS that were subsequently degraded by methanogens. Therefore, reducing proteins containing sulfur amino acids along with increasing methanogenic activity appears to be an effective strategy to control VOSCs and the associated odor problem.
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    Impact of substrate feed patterns on solids reduction by the cannibal process
    (2015-03-01)
    Khanthongthip, Passkorn
    ;
    Novak, John T.
    ;
    Doyle, Michael L.
    A biological solids reduction process that uses a sidestream anaerobic reactor (Cannibal process) was investigated to better understand why variations in solids reduction occur in field installations. Field observations indicated that single stage, high sludge age processes would frequently not provide a low solids yield. To study this, laboratory sequencing batch reactors were operated, one as a conventional activated sludge system and the other two with a side-stream anaerobic reactors. The controland oneanaerobic side-stream system were operated with a 5-minute feed cycle to mimic a plug flow system. The other anaerobic side-stream system operated with a 4-hour feed cycle to simulate complete mix. The 5 minutes feed Cannibal system generated up to 80% less biological solids than the control. The 4 hours feed Cannibal system produced less biological solids than the conventional activated sludge system but remained higher than for system with a 5-minute feed time.