Macrophyte and substrate selection for the treatment of wastewater from cheese production

HADAD, H.R.; SANCHEZ, G. C.; NOCETTI, E; DI LUCA, G. A; MAINE, M. A.; MUFARREGE, M.M

Aarhus

Simposio; 8th International Symposium on Wetland Pollutant Dynamics and Control-WETPOL 2019; 2019

Aarhus University

A hybrid wetland (HW) system will be constructed for the treatment of cheese production wastewater. The aim of this study was to select the macrophytes and the substrates to be used in the horizontal subsurface flow wetland (HSSFW), second stage of the HW. HSSFWs were simulated using plastic reactors of 20 L capacity arranged by duplicated outdoors under semi-transparent plastic roof. The reactors were planted with Typha domingensis and Canna glauca, collected from natural wetlands. LECA (light expanded clay aggregate) and river gravel were used as substrates. In each treatment, one of the two types of substrates and macrophytes were used. The experiment began after a period of acclimatization of threemonths to achieve a good development of the roots and rhizomes and to increase the microbial biomass in the substrate. Real wastewater from cheese production was used. It receives a previous treatment to eliminate fats and to reduce the organic load. Hydraulic residence time (HRT) was seven days. The duration of the study was three months. Wastewater samples were collected before and after each loading. Chemical oxygen demand (COD), biological oxygen demand (BOD), total Kjeldahl nitrogen (TKN),ammonium (NH4+-N), total phosphorus (TP) and soluble reactive phosphorus (SRP) were determined in all wastewater samples according APHA (2012). The chemical composition of the initial wastewater used in the experiment and the mean removal efficiencies are showed in Figure 1. The BOD/COD ratio was higher than 0.5 in all cases. HSSFW proved to be efficient for COD and BOD removals, without significant differences among treatments. For the other studied parameters, HSSFWs with river gravel and planted with T. domingensis presented the lowest removal efficiencies. The highest removals of TKN and NH4+-N was obtained in HSSFWs planted with C.glauca. The removal of TP and SRP did not present significant differences between the plant species using LECA as substrate. HSSFWs proved to be efficient for the treatment of cheese production effluent. HSSFWs with LECA or river gravel planted with C. glauca would be the best option for this wastewater treatment.