Biocidal agents (BAs) are widely used in environmentally safe toilet complexes (ESTC) of passenger railcars to suppress microbial activity in fecal sludge (FS). The subsequent disposal of BA-containing FS at municipal sewage treatment facilities adversely affects their work due to the loss of activated sludge. The antimicrobial properties of BAs based on quaternary ammonium compounds (QAC) and polyhexamethylene guanidine (PHMG), as well as methods for its neutralization, have been studied. It was confirmed that BAs based on QAC and PHMG have an antimicrobial effect on various groups of bacteria, reducing their number by 10-100 or more times. It was found that FS contains two groups of microorganisms with different sensitivities to BA. Methods for the deactivation of BA antimicrobial action in FS were tested with (1) a deactivating agent; (2) incubation with thermophilically digested wastewater sludge as a source of the methanogenic microbial community; and (3) chemical deactivation via acidification or alkalization. The highest efficiency was obtained from thermophilic anaerobic digestion with the pretreatment of FS with a strong acid.

Rational ways of treatment of fecal sludge (FS) from environmentally friendly toilet complexes of railway cars preserved with a biocidal agent (BA) based on quaternary ammonium compounds (QAC) and polyhexamethylene guanidine (PHMG) are considered. The bacteriostatic effect of BA on different groups (aerobic and anaerobic) of microorganisms in preserved FS was shown. An effective method for reducing the toxic effect of BA in FS by means of pretreatment with acid prior to microbiological processing has been proposed. The conditions for carrying out the process were selected, allowing to increase the efficiency of anaerobic fermentation of FS containing BA.

Biocidal agents (BA) are widely used in environmentally safe toilet complexes (ESTC) of passenger railcars to suppress microbial activity in fаecal sludge (FS). Subsequent disposal of BA-containing FS at municipal sewage treatment facilities adversely affects their work due to the loss of activated sludge. The antimicrobial properties of BA, based on quaternary ammonium compounds (QAC) and polyhexamethylene guanidine (PHMG), as well as methods for its neutralization, have been studied. It was confirmed that BA based on QAC and PHMG has an antimicrobial effect on various groups of bacteria, reducing their number by 10-100 or more times. It was found that FS contains two groups of microorganisms with different sensitivity to BA. Methods for deactivation of the BA antimicrobial action in FS were tested using: (1), a deactivating agent; (2), incubation with thermophilically digested wastewater sludge as a source of the microbial methanogenic community; and (3), chemical deactivation by acidification or alkalization. The highest efficiency was shown by the method of deactivation of BA via thermophilic anaerobic digestion with pretreatment of FS with a strong acid biocide, fаecal sludge of ESTC of passenger railcars, antimicrobial activity, quaternary ammonium compounds, polyhexamethylene guanidine, deactivator, methanogenic microbial community This work was financially supported by the Ministry of Science and Higher Education of the Russian Federation.