Landfill leachate treatment by immediate one-step lime precipitation, carbonation, and phytoremediation fine-tuning.

The high pollutant load of sanitary landfill leachates poses a huge challenge in the search for efficient and environment friendly solutions for their treatment. The objective of this work was to study an integrated solution of environmentally friendly technologies - immediate one-step lime precipitation (IOSLP), carbonation (CB), and phytoremediation (Phyt) - to treat a sanitary landfill leachate. In the leachate sample treatment by IOSLP, the influence of CaO concentration (18.2-33.3 gCaO L-1) and stirring time (2-60 min) on the sludge sedimentability and pollutant removal was studied. Organic load and ammonia nitrogen (AN) removal increases with CaO added, as well as sludge volume. Stirring time has a small influence on organic load and AN removal, presenting a minimum for sludge volume. Thus, the best operational conditions were chosen as 27.6 gCaO L-1, and 40-min stirring time, with 64% chemical oxygen demand (COD) removal. Sludge humidity was 2.1%, making dewatering needless. IOSLP supernatant was submitted to CB by atmospheric CO2, and 100% removals in AN and hardness were attained. Effluents from IOSLP and IOSLP + CB were utilized in Phyt tests, with Vetiver (Chrysopogon zizanioides (L.) Roberty). The best COD removal (37%) during Phyt was attained for the samples treated by IOSLP + CB.

Immediate one-step lime precipitation process for the valorization of winery wastewater to agricultural purposes.

The winery wastewater (WW) of the Village of Vidigueira, in south of Portugal, presented an acid pH (4.26 ± 0.029), a high content of chemical oxygen demand (COD = 3236 ± 30.43 mg L-1), turbidity (160.0 ± 7.68 NTU), total P (155.5 ± 6.36 mg L-1) K (100.5 mg L-1), and low level of metals: Pb, Cd, Cu, Ni, Mn, Fe, Zn. The K and the total P content could make them attractive from an agricultural point of view. However, the high turbidity biochemical oxygen demand (BOD5 = 1266.7 ± 208.7 mg O2 L-1) fecal coliforms (45 ± 29.8 ufc/100 mL) and toxicological total phenols 13.239 ± 3.007 mg galic acid L-1 is the main limiting parameters. By using 5 g L-1 of lime solution, the best reactional conditions are achieved: pH = 12 with a minimum volume of the produced sludge's, 33.5 ± 4.92 mL L-1. These reactional conditions allow reaching high removal levels of BOD5, turbidity, total P, and total phenols: 77.9, 98.7%, 87.1%, and 99.9%, respectively. Simultaneously, the fecal coliforms and Enterococcus are 100% eliminated. The precipitate obtained is rich in calcium (2.7891 ± 0.4350 mg Ca kg-1) organic matter (10.05 ± 0.11%), P (895.0 ± 35.4 mg P2O5 kg-1), and K (990.0 ± 84.9 mg K2O kg-1). During carbonatation reactions, the pH (7.46) and electrical conductivity (EC) (1.805 dS m-1) decreased spontaneously while the Ca2+, K+, and F- kept high: 426.53 mg L-1, 240.53 mg L-1, 176.03 mg L-1, respectively.