Regrowth of Potential Opportunistic Pathogens and Algae in Reclaimed-Water Distribution Systems

Abstract

A study of the quality of reclaimed water in treated effluent, after storage, and at three points in the distribution system of four plants in California, Florida, Massachusetts, and New York was conducted for 1 year. The plants had different treatment processes (conventional versus membrane bioreactor), production capacities, and methods for storage of the water, and the intended end uses of the water were different. The analysis focused on the occurrence of indicator bacteria (heterotrophic bacteria, coliforms, Escherichia coli, and enterococci) and opportunistic pathogens (Aeromonas spp., enteropathogenic E. coli O157:H7, Legionella spp., Mycobacterium spp., and Pseudomonas spp.), as well as algae. Using immunological methods, E. coli O157:H7 was detected in the effluent of only one system, but it was not detected at the sampling points, suggesting that its survival in the system was poor. Although all of the treatment systems effectively reduced the levels of bacteria in the effluent, bacteria regrew in the reservoir and distribution systems because of the loss of residual disinfectant and high assimilable organic carbon levels. In the systems with open reservoirs, algal growth reduced the water quality by increasing the turbidity and accumulating at the end of the distribution system. Opportunistic pathogens, notably Aeromonas, Legionella, Mycobacterium, and Pseudomonas, occurred more frequently than indicator bacteria (enterococci, coliforms, and E. coli). The Mycobacterium spp. were very diverse and occurred most frequently in membrane bioreactor systems, and Mycobacterium cookii was identified more often than the other species. The public health risk associated with these opportunistic pathogens in reclaimed water is unknown. Collectively, our results show the need to develop best management practices for reclaimed water to control bacterial regrowth and degradation of water before it is utilized at the point of use.

Removal of Pathogens by Membrane Bioreactors: A Review of the Mechanisms, Influencing Factors and Reduction in Chemical Disinfectant Dosing

“…However, the regrowth of pathogens, such as Aeromonas, Mycobacterium, and Legionella, has been reported in the distribution system irrespective of the treatment technology used, including CAS processes and MBRs [123,124]. Thus, the post-treatment of MBR effluents as well as effective effluent monitoring to confirm the integrity of the process is necessary in order to ensure environmental and public health protection.…”

Estabilización anaerobia mesofílica y termofílica de lodos activados provenientes de la industria cervecera

“…Otro factor asociado fue la disminución del sustrato. los microorganismos generan entre ellos interacciones positivas o negativas como consecuencia de la competencia por nutrientes, espacio y luz, lo cual origina la depredación interespecífica, acumulación de sustancias no degradables, tóxicas o materiales inorgánicos que actúan como inhibidores o activadores de los organismos que controlan el crecimiento a nivel de cada población y en consecuencia, de la producción y tipo de biomasa, Jjemba [14]. se puede inferir que la acción conjunta de estos factores conllevó al control de las densidades poblacionales, cuya dinámica dependió del afluente y se reflejó en la estabilización del reactor.…”

The effect of iron corrosion in cast iron pipes on the microbiological quality of drinking water: a laboratory and field investigation

“…The release of soluble or particulate iron corrosion byproducts to the water also decreases the aesthetic quality (Lytle et al, 2004). High levels of ferrous ion in drinking water can cause adverse health effects such as kidney diseases and tooth problems (Jjemba et al, 2010). The effects of toxic doses of iron include depression, rapid and shallow respiration, coma, convulsions, respiratory failure, and cardiac arrest.…”

“…This may reduce the amount of available chlorine all through the distribution system. Recent studies have documented that the rapid dissipation of the disinfectant in drinking water, promotes regrowth of microorganisms, some of which are potential opportunistic pathogens (Jjemba et al, 2010). Regrowth of microorganisms has been highlighted as the most likely source of organisms detected near the point of use in water distribution systems (Muyima, and Ngcakani, 1998).…”