• Energy Research

The use of waste materials as organic amendments in soil remediation can affect metal solubility; this interaction will vary with the characteristics of the organic matter that is added to the soil. A pot experiment was carried out in a calcareous, metal-polluted soil, using Beta maritima L. as an indicator species for the treatment effects on metal solubility. The treatments were: fresh solid olive husk, a mature compost, their respective water extracts (as the most reactive and biodegradable fraction) and an unamended, control soil. The compost reduced metal availability and plant uptake, while fresh olive husk favoured Mn bioavailability and produced phytotoxicity. The water-soluble extract from fresh solid olive husk also provoked elevated Mn solubility in soil, but did not increase Mn uptake by plants. The application of water-soluble organic matter obtained from compost did not affect heavy metal solubility significantly. Therefore, composted olive husk seems to be the most-appropriate material for the development of bioremediation strategies.

Abstract The increasing shortage of conventional water for crop irrigation in arid and semiarid regions is encouraging the use of non-conventional resources. Nevertheless, concern about the presence and possible negative effects of Contaminants of Emerging Concern (CECs) in reclaimed waters can put in danger the possible use of this water source. To clarify the guarantees that reclaimed water offers, a mesocosm study was carried out. Pots with a lettuce were watered with three different types of water (distilled, reclaimed and spiked with CECs). The results showed a low concentration of these compounds in leachates and in plant tissues when reclaimed water was used. However, their concentrations were high when pots were watered with spiked water, mainly for carbamazepine (CBZ), reaching a maximum of 2982 ng L− 1 in leachates and 45.2 ng g− 1 in plant roots. In lettuces watered with spiked water, CBZ was found in edible part at very low concentrations that did not imply any human risk. Finally, an acute toxicity test was performed with the leachates, which resulted only slightly toxic for spiked water. This work confirms that, with the current technical improvements of active sludge water treatment, reclaimed water can be used for irrigation without risk for CECs contamination.