Use of recycled construction and demolition waste as substrate in constructed wetlands for the wastewater treatment of cheese production.

Recycled building debris has recently emerged as a suitable wetland infill substrate due to its low density, exceptional water absorption capabilities, and high porosity. This study investigated, for the first time, the use of construction demolition wastes (CDW), and rock processing residues (RPR) as substrate materials in vertical-horizontal flow hybrid constructed wetlands for the treatment of cheese production wastewater. Results showed that the use of both CDW as well as RPR, as substrate material, provided an equal or even better quality of treated wastewater compared to the conventional use of gravel as a substrate. High removal efficiencies were recorded for turbidity (CDW: 91-92%, RPR: 97%), solids (CDW: 85-88%, RPR: 96-97%), organic matter (CDW: 79-84%, RPR: 96-98%), and total phosphorus (CDW: 72-76%, RPR: 87%) for both examined recycled materials. During the experiment, different loadings rates (HLR) were tested: 25 mm d-1 and 37.5 mm d-1. Radiological measurements indicate that, their use did not cause toxic effects on the environment, as the amounts of radioactivity found in the effluent of the systems are not significant. Increasing the hydraulic loading rate appeared to have no negative effect on pollutant removal, as the systems and plants were fully acclimated and mature. This approach offers several advantages, including the use of readily available and abundant waste material, potential cost savings, and the environmental benefits of recycling CDW and RPR instead of disposing of them in landfills.

Cultivation of the macrophyte Lemna minor and the microalgae Chlorella sorokiniana in thermal mineral waters: Biomass characteristics, radioisotopes and heavy metals content.

Microalgae and macrophytes are commonly used as human and animal food supplements. We examined the cultivation of the microalgae Chlorella sorokiniana and the duckweed Lemna minor in thermal waters under batch and sequencing batch conditions and we characterized the produced biomass for the presence of essential nutrients as well as for heavy metals and radioisotope content. The highest specific growth rate for the microalgae was observed when 5 or 15 mg/L N were supplemented while the optimal conditions for Lemna minor were observed in the co-presence of 5 mg/L N and 1.7 mg/L P. Lemna minor presented higher concentrations of proteins and lipids comparing to the studied microalgae. Both organisms contained high amounts of lutein (up to 1378 mg/kg for Lemna minor) and chlorophyll (up to 1518 mg/kg for Lemna minor) while ß-carotene and tocopherols were found at lower concentrations, not exceeding a few tens of mg/kg. The heavy metal content varied between the two species. Lemna minor accumulated more Cd, Cu, K, Mn, Na, Ni, and Zn whereas Al, Ca and Mg were higher in Chlorella sorokiniana. Both organisms could be a significant source of essential metals but the occasional exceedance of the statutory levels of toxic metals in food products raises concern for potential risk to either humans or animals. Application of gamma-spectroscopy to quantify the effective dose to humans from 228Ra, 226Ra and 40K showed that Chlorella sorokiniana was well under the radiological limits while the collected mass of Lemna minor was too small for radiological measurements with confidence.

Risk assessment of triclosan released from sewage treatment plants in European rivers using a combination of risk quotient methodology and Monte Carlo simulation.

Ιn this study a probabilistic risk assessment was applied to investigate the environmental risks for the European aquatic environment associated with triclosan (TCS) occurrence in treated wastewater. The concentrations of TCS in effluents of European Sewage Treatment Plants (STPs) were recorded through literature review, while toxicity data was collected for three groups of aquatic organisms (algae, Daphnia magna and fish). The ratio of Measured Environmental Concentration (MEC) and Predicted No Effect Concentration (PNEC), expressed as a Risk Quotient (RQ), was calculated for risk characterization, while Monte Carlo simulation was applied to quantify the associated uncertainty. TCS monitoring data was available for 349 STPs located in 15 out of the 50 European countries. Its mean concentrations in STPs effluents ranged between 2.2ngL-1 and 47,800ngL-1. Higher TCS concentrations were observed in primarily treated wastewater; whereas no differences among countries or among secondary and tertiary effluents on the basis of the whole set of collected data were found. The 95th percentile of RQ for TCS was higher than 1 (in algae) for rivers with dilution factors (DFs) equal to or lower than 100, when the maximum concentration values were used, whereas the 95th percentile of RQ exceeded 1 for rivers with DFs up to 10, in cases where the calculations were based on mean concentration values. The probability that RQ exceeds 1 in rivers (for algae) ranged from 0.2% (DF=1000) to 45% (DF=2), when calculations are based on mean concentration values. The corresponding probabilities in rivers with DFs equal to 2 for Daphnia magna and fish were 0.7% and 0.4%, respectively. We propose that TCS monitoring should be intensified, especially on smaller rivers, to verify the findings of this study for possible environmental risks.