Importance of Composing Representative Samples According to the Theory of Sampling (TOS) for the Reuse of Water Treatment Sludge

Author(s)

Tsugawa, Juliana Keiko ; Silva Sabino, Evelyn Fernandes Da ; Monte, Renata ; Gimenez Boscov, Maria Eugenia ; LopezAcosta, NP ; MartinezHernandez, E ; EspinosaSantiago, AL ; MendozaPromotor, JA ; Lopez, AO

• Document type: Journal article
• Source: GEOTECHNICAL ENGINEERING IN THE XXI CENTURY: LESSONS LEARNED AND FUTURE CHALLENGES; v. N/A, p. 8-pg., 2019-01-01.

Abstract

In Brazil, water treatment sludge (WTS) production reaches 1.9 million m(3)/day(2), mostly discharged in rivers, and minorly destined to landfills or sludge treatment plants. WTS reuse as a geotechnical material, a sustainable alternative to reduce environmental impacts, demands knowledge about WTS behavior. However, WTS characteristics vary for each WTP and along time for the same WTP, due to local geology, quality of raw water, type and quantity of coagulant, dewatering process, among others. Sampling procedures may also cause significant variation of tests results. To separate sampling errors from "real" variation of characteristics, representative samples for laboratorial tests must be composed using concepts of the Theory of Sampling (TOS). This paper evaluates the effects of sampling method and number of increments to compose the representative sample on the variability of water content and specific gravity of WTS generated at Cubatao WTP in Sao Paulo, Brazil. Results, valuated by analysis of variance methodology (ANOVA), indicated that both control parameters are influenced by the sampling method and also by the number of increments. In conclusion, the application of TOS concepts to compose representative samples is mandatory to obtain reliable WTS parameters. (AU)