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

Abstract

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 mgO 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 mS·cm −1 (greenhouse 1), and from 4.94 to 6.94 mS·cm −1 (greenhouse 2). No statistically significant correlations were noted between TN and TP, or between TP and EC.

Archives of Environmental Protection

“…The density values of electric current were adjusted based on the literature data (Zhao et al 2011). Synthetic wastewater with the composition similar to that of wastewater from the soilless cultivation of tomatoes, adopted after Saxena and Bassi (2013) and Mielcarek et al (2019) was used. Sodium acetate was added to wastewater as a source of carbon in part II of the study to provide appropriate conditions for biofilm development.…”

Electric Power Consumption and Current Efficiency of Electrochemical and Electrobiological Rotating Disk Contactors Removing Nutrients from Wastewater Generated in Soil-Less Plant Cultivation Systems

“…Synthetic wastewater was used in the study. Its characteristics were similar to the wastewater from soil-less cultivation of tomatoes, which is the most common cultivation method of these vegetables, adopted after Saxena and Bassi [2] as well as Mielcarek et al [1]. To provide appropriate conditions for biofilm development, sodium acetate was added to wastewater as a source of carbon at the second stage of the study.…”

“…In Poland, almost all cultivation of plants with soil-less methods proceeds in open systems, from where the excess of nutrient medium is discharged into the ground or to surface waters. Concentrations of nutrients in wastewater from, e.g., tomato crops, may even reach up to 466 mg N/L for nitrate nitrogen and up to 370 mg P/L for total phosphorus [1]. Wastewater of this type should not be discharged to the ground nor to natural water without pre-treatment [1,2].…”

Novel Materials as Exogenous Carbon Sources for Denitrifying Biofilters

“…Unfortunately, this type of crop generates huge amounts of wastewater with high concentrations of biogenic compounds, and therefore constitutes a significant source of pollution [2]. In most places, soilless cultivation is carried out in open irrigation systems, which means that wastewater is not recirculated [3] and is removed to the natural environment [4,5]. Open tomato soilless cultivation may result in 230 kg•ha −1 and 54 kg•ha −1 of nitrogen and phosphorus, respectively, released to the soil or surface water monthly.…”

“…During a 150 day growing season, approximately 1000 m 3 •ha −1 of a nutrient solution is needed, and approximately 250 m 3 of wastewater is produced [6]. The result is a high concentration of phosphorus in wastewater, ranging from 35.4 to 104.0 mg P/L, and for nitrogen pollutants from 270.0 to 614.9 mg N/L and low COD (Chemical Oxygen Demand), which is usually below 50 mg O 2 /L [4]. Recent regulations introduced in the EU emphasize the modernization of soilless farming systems to recover water and fertilizer ingredients.…”