Particle size distribution as a useful tool for microbial detection.
Worldwide, raw or treated wastewater is used for irrigation. However, this practice implies that the microbial content must be controlled. Unfortunately, detection techniques for microorganisms are costly, time consuming, and require highly trained personnel. For these reasons, this study used particle size distribution to measure the microbial quality of wastewater through correlations between the number or volume of particles and the concentration of fecal coliforms, Salmonella spp. and helminth ova. Such correlations were obtained for both raw and chemically treated wastewater. The best fit was the one for helminth ova, which applies for both the influent and effluent and also for all the coagulants involved. This technique allows the on-line quantification of helminth ova at a cost of US$3 and it takes only 5 minutes, instead of the US$70 and 5 days for the standard technique. With respect to the coagulants applied, their behavior is different only for particles smaller than 8 microm, and thus this value is considered as the critical size for this particular treatment. The best coagulant was the aluminium polychloride. In addition, this work establishes the distribution of COD, TSS, nitrogen, and phosphorous for particles smaller and larger than 20 microm.
Chavez
A
A
Engineering Institute Group, Treatment and Reuse, UNAM, Ciudad Universitaria, Coyoacan 04510 Mexico City, DF. AChavezM@iingen.unam.mx
Jimenez
B
B
Maya
C
C
D000383:Agriculture; D003247:Conservation of Natural Resources; D003365:Costs and Cost Analysis; D004784:Environmental Monitoring / Q000191:economics / Q000379:methods; D010316:Particle Size; D014865:Waste Disposal, Fluid / Q000379:methods; D014871:Water Microbiology; D018508:Water Purification