Solar distillation of olive mill wastewater

A solar still was employed for the dewatering of olive mill wastewater over a series of consecutive days. The collected distillate and the remaining pulp were analyzed to test the method for treating agro-food industry wastewater. The efficiency of solar distillation of olive mill wastewaters was examined. Due to reduced energy consumption and relatively high temperatures achieved in the still, solar distillation could be applied in any process where separation of liquid and solid phase is required. A quantity of olive mill wastewater was left inside the solar still for 9 days, under outdoor conditions. Critical quality parameters (e.g. chemical oxygen demand, pH, total and volatile solids, total Kjeldahl nitrogen) were determined by daily sampling of both the distillate and the basin liquid. In addition, solar radiation and liquid, glass and ambient temperatures were recorded. It was shown that the distillate produced was free from solids, 80% lower in terms of COD and 90% in terms of TKN, while the basin residual was in solid form with only 15% water concentration and without any odor emissions

Stratified Energy-Storage Vessels - Characterization of Performance and Modeling of Mixing Behavior

WOS: A1994NA99700003The performance of several solar energy storage vessels is extensively tested and recorded according to the CSTG procedure and their efficiencies in energy delivering is calculated. The stratification inside the vessels is determined by matching the profiles to predictions from a layers-in-series model. The model is extended to account for dead spaces inside the vessel and is proven to be useful in evaluating the performance of stratified solar energy storage vessels

Selecting an appropriate Multi-Criteria Decision Aid Technique for renewable energy planning

This article develops a methodological framework to provide insights regarding the suitability of multi-criteria techniques in the context of renewable energy planning. The second section presents main characteristics of the particular decision-making process. The third section presents the main multi-criteria analysis methods, and the fourth section reveals the requirements of the techniques for renewable energy planning and the main attributes under which these methods should be evaluated. Subsequently, in the fifth section, a comparative matrix is created with the various appropriate multi-criteria techniques and their performance. Finally in the sixth sec tion, we present our conclusions

Evaluation of the performance of a pilot-scale solar still for olive mill wastewater treatment

A pilot-scale solar still was constructed to evaluate the use of solar distillation for olive mill wastewater management. Conventional distillation experiments were initially conducted and showed that the increase of temperature resulted to higher concentrations of total phenols, tyrosol and hydroxytyrosol in the distillates. Afterwards, four experiments were performed in the pilot system with different types of olive mill wastewater to examine the effect of temperature and the role of underfloor heating system on its performance. The use of the heated underfloor resulted to higher average and maximum daily temperatures in the still and increased the production rates of the distillates, which reached up to 4.10 L/d m2. Liquid chromatography – high resolution mass spectrometry analysis detected concentrations of tyrosol and 4- hydroxybenzoic acid in the collected distillates at concentrations up to 0.70 and 0.10 mg/L, respectively. At the same time, a strong correlation was observed between the average daily temperature in the solar still and the concentrations of total phenols in the recovered distillates. The implementation of mass balances showed that almost 33% of the total input phenols found in olive mill wastewater remained in the solid residue. Eight phenolic compounds were detected in this material at concentrations ranging between 0.04 mg/kg (quinic acid) and 8.8 mg/kg (hydroxytyrosol), while its calorific value ranged from 15.28 MJ/kg up to 25.12 MJ/kg. Economic evaluation was implemented for the case of upscaling the said pilot system for operation at a medium size three-phase Greek olive mill. Taking into consideration that the distillate could be reused for the washing and malaxation of olive fruits, while solid residual could be sold as biofuel, the operational and overall costs were estimated to 0.60 and 1.21 €/m3, respectively. © 2022 Elsevier Lt