Presentation Title

Analysis of Particle Size and Metal Content of a Decentralized Wastewater Treatment System

Start Date

November 2016

End Date

November 2016

Location

HUB 302-#69

Type of Presentation

Poster

Abstract

Decentralized Wastewater Treatment Systems (DEWATS) are sustainable, economical, and low maintenance wastewater treatment systems. The system treats domestic waste from 84 low-medium income households in the Newlands suburb in Durban, South Africa. Particle sizes were analyzed using total suspended solids, volatile suspended solids, chemical oxygen demand, microscopy, and elemental composition analysis. Raw samples and five particle fractions (20 μm, 11 μm, 1.5 μm, 0.7 μm, 0.45 μm) were investigated. Sludge metal content was determined via inductively coupled plasma optical emission spectrometry (ICP-OES). Digestions were completed using two different methods, the first used concentrated nitric acid and the second used Aqua Regia. Concentration of suspended solids in the 20 μm fraction decreased from 80 mg/L to 25 mg/L. The COD from the first anaerobic baffled reactor to the second anaerobic filter decreased from 500 mg/L to 375mg/L, which suggests that particles are not only broken down but also degraded as they moved through the system. Results indicate that the metal content within the sludge layer may be suitable for reuse applications. The trace metals Cd, Co, Ni and Pb were below detection limits of the ICP-OES. In addition, Al and Fe (which are not elements of concern when present in biosolids) ranged from 26.4 to 32.3 mg/g and 15.0 to 17.1 mg/g representing levels that will help the amended soil to keep potentially toxic trace elements in bound form. Understanding of the dynamics of metals and carbon in the DEWAT’s biosolids provides important information to achieve safe application for reuse purposes.

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Nov 12th, 4:00 PM Nov 12th, 5:00 PM

Analysis of Particle Size and Metal Content of a Decentralized Wastewater Treatment System

HUB 302-#69

Decentralized Wastewater Treatment Systems (DEWATS) are sustainable, economical, and low maintenance wastewater treatment systems. The system treats domestic waste from 84 low-medium income households in the Newlands suburb in Durban, South Africa. Particle sizes were analyzed using total suspended solids, volatile suspended solids, chemical oxygen demand, microscopy, and elemental composition analysis. Raw samples and five particle fractions (20 μm, 11 μm, 1.5 μm, 0.7 μm, 0.45 μm) were investigated. Sludge metal content was determined via inductively coupled plasma optical emission spectrometry (ICP-OES). Digestions were completed using two different methods, the first used concentrated nitric acid and the second used Aqua Regia. Concentration of suspended solids in the 20 μm fraction decreased from 80 mg/L to 25 mg/L. The COD from the first anaerobic baffled reactor to the second anaerobic filter decreased from 500 mg/L to 375mg/L, which suggests that particles are not only broken down but also degraded as they moved through the system. Results indicate that the metal content within the sludge layer may be suitable for reuse applications. The trace metals Cd, Co, Ni and Pb were below detection limits of the ICP-OES. In addition, Al and Fe (which are not elements of concern when present in biosolids) ranged from 26.4 to 32.3 mg/g and 15.0 to 17.1 mg/g representing levels that will help the amended soil to keep potentially toxic trace elements in bound form. Understanding of the dynamics of metals and carbon in the DEWAT’s biosolids provides important information to achieve safe application for reuse purposes.