Analysis of Wastewater Generated in Greenhouse Soilless Tomato Cultivation in Central Europe

Soilless plantations under cover constitute a significant part of horticulture. This study aimed at determining the qualitative composition of wastewater generated from the soilless cultivation of tomato under cover. This is important for managing the wastewater, which may be recirculated to allow the or employ a partial or complete recovery of minerals. Two plantations located in north-eastern Poland, which differed in the type of substratum (coconut fiber or rockwool), were studied. The generated wastewater was characterized by a low content of organic matter and a high concentration of total nitrogen (TN), total phosphorus (TP), and salinity (EC). Over 99% of the TN was constituted by nitrates. The chemical oxygen demand (COD) changed from 50.07 to 75.82 mg.O-2.L-1 (greenhouse 1), and from 37.35 to 78.12 mgO(2).L-1 (greenhouse 2); the content of TN changed from 403.59 to 614.89 mgN.L-1 (greenhouse 1), and from 270.00 to 577.40 mgN.L-1 (greenhouse 2); that of TP changed from 35.44 to 78.00 mgP.L-1 (greenhouse 1), and from 54.10 to 104.00 mgP.L-1 (greenhouse 2); and the EC changed from 3.53 to 6.93 mScm(-1) (greenhouse 1), and from 4.94 to 6.94 mScm(-1) (greenhouse 2). No statistically significant correlations were noted between TN and TP, or between TP and EC.