391 Sludge Solar Drying: Thermal, Physical and Chemical Characterization

Friday, November 6, 2009: 9:40 AM
Charolais (Camino Real Hotel)
Alma Delia Cota , Department of Chemistry, Universidad Autonoma de Ciudad Juarez, Cd. Juarez, Mexico
Edgar Espinoza , Department of Chemistry, Universidad Autonoma de Ciudad Juarez, Cd. Juarez, Mexico
Cynthia Figueroa , Department of Chemistry, Universidad Autonoma de Ciudad Juarez, Cd. Juarez, Mexico
Diego Fayett , Department of Chemistry, Universidad Autonoma de Ciudad Juarez, Cd. Juarez, Mexico
Claudia Avitia , Department of Chemistry, Universidad Autonoma de Ciudad Juarez, Cd. Juarez, Mexico
Gilberto Lares , Department of Chemistry, Universidad Autonoma de Ciudad Juarez, Cd. Juarez, Mexico
Katya Carrasco , Department of Chemistry, Universidad Autonoma de Ciudad Juarez, Cd. Juarez, Mexico

ABSTRACT

The large volumes of sludge produced during wastewater treatment  (WWT) make difficult and costly its handling and disposal. In Mexico, as in most developing countries, WWT has not yet reached its maximum production. Figure 1 shows the number of WWT plants and the capacity installed in Mexico according to Secretariat of Environment and Natural Resources (SEMARNAT). The 135 tons of sludge produced per day in the WWT Plant zona Norte of Ciudad Juarez, in Mexico represents a social and environmental problem. Sludge is composed by more than 95% of water and high concentrations of bacteria, viruses and parasites, as well as toxic organic compounds and heavy metals. Several studies have demonstrated its potential use in agricultural activities due to its high content of macronutrients. However, its use could cause problems toward human health and environment. Solar drying of sludge is a  feasible technology for improving its management at low cost. The solar experimental setup used on this study was designed and built to evaluate such technology for reducing volume and also to determine its capability for disinfecting sludge with high-pathogenic content. The effectiveness of the process was carried out by thermal, microbiological, chemical and physicochemical parameters. Water content in sludge, fecal coliforms, Salmonella spp., helmint eggs, heavy metals, pH, phosphates and nitrates were included as the effectiveness indicators (Figure 2). All of them were dynamically quantified during the solar drying of wastewater sludge.

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Figure 1. Number of WWT Plants and Installed capacities in Mexico.

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Figure 2. Presence of Salmonella spp. in  sludge during solar drying.