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Manual Treatment of Urban Wastewater by Chemical Precipitation for Production of Hydroponic Nutrient Solutions

2020; Polish Society of Ecological Engineering; Volume: 21; Issue: 3 Linguagem: Inglês

10.12911/22998993/118286

2299-8993

Tânia Correia, Mariana Regato, Adelaide Almeida, Maria Teresa Santos, Leonor Amaral, Fátima Carvalho,

Constructed Wetlands for Wastewater Treatment

An urban wastewater treatment system was developed in Portugal for posterior in situ feasibility testing at the Bulgarian Antarctic Base, using its domestic wastewater.The aim of this system was to develop a low cost, integrated approach for wastewater treatment and production of nutrient solutions (NS) for hydroponic cultivation of lettuce (Lactuca sativa var.crispa) in Antarctic stations, or any other place where the lack of resources and logistical hardships make the wastewater treatment and reuse impractical.The wastewater treatment system consisted in manual agitation lime chemical precipitation (LCPm) and effluent natural neutralization (NN) by atmospheric CO 2 carbonation reactions (with and without air injection).The resulting effluent/NS had macronutrient values (nitrogen and phosphorous) for the hydroponic cultivation of lettuce below the values of commercial NS and a high pH (pH ≈ 8).The treatment achieved a total coliform removal rate of 100%.Before the LCPm treatment system development, several lime-based reagents were tested under different reaction pH and using mechanical agitation, to access their organic matter removal efficiency, as chemical oxygen demand (COD).The best COD removal results obtained were: commercial Ca(OH) 2 (pH 11.5 -89%), reagent grade Ca(OH) 2 (pH 11.5 -79%) and CaO (pH 12.0 -64%).