Determination of thermal capacity of processed sorbents from residual biomass of Chlorella Sorokiniana and duckweed Lemna Minor

Abstract

Our article reviews the issues arising during the process of wastewater purification and utilization of spent adsorbents. We are offering different ways of utilization of spent sorbents produced from residual biomass of Chlorella Sorokiniana microalgae and Lemna Minor duckweed. We review the technology of adsorbent production from agricultural waste (carbonized millet husks), wastes of the thermally expanded graphite and chitosan biopolymer production, and residual biomass of Chlorella Sorokiniana microalgae and Lemna Minor duckweed, which is formed after all the valuable components have been extracted from the algae and duckweed. We have conducted a thermogravimetric analysis that demonstrated that the spent sorbents’ decomposition when exposed to high temperatures results in a variety of exothermic effects in the 300 to 500 °C range. This fact allows us to recommend application of spent sorbents as a fuel for energy generation.. For the first time we determine the specific heat of combustion of spent sorbents used in wastewater purification from oils (22,857–25,220 kJ/kg) and from heavy metal ions (19,079–21,117 kJ/kg). We demonstrate that the value of specific heat of combustion of spent sorbents produced from residual biomass is not less than that of classic fuels such as coals and brown coals. The specific heat value of combustion of spent sorbents used in wastewater purification from oils is higher than that of those used in wastewater purification from heavy metal ions because of the oil carbohydrates adsorbed on sorbents, which increases the material’s calorific value.

Keywords

• spent sorbents’ utilization
• fuel
• residual biomass of chlorella sorokiniana microalgae and lemna minor duckweed
• water purification