Plasterboard sheet applied in vertical-flow constructed wetlands: Nutrients removal, microbial diversity, and mechanisms

Wetlands are an economically viable alternative for decentralized wastewater treatment. Plasterboard sheets (PS) are commonly used in civil construction; however, the waste generated could be an environmental concern. Thus, fragments of plasterboard sheets and modified PS were used as substrates in two sequencing-batch vertical -flow constructed wetlands (VFCW) of 28 L of the working volume to evaluate the carbonaceous, nitrogenous, and phosphorous matter removal from synthetic wastewater, combining sewage treatment and reuse of civil con-struction waste. The systems, planted with Eichhornia crassipes, were named CW-P (11.36 kg of PS fragments and 30 % porosity) and CW-MP (9.34 kg of modified PS fragments and 35 % porosity). The systems were evaluated under two different sampling conditions after 24 h (Phase I) and 48 h (Phase II) for 308 days. The PS was characterized using SEM, SED, and XRF analyses, and the bacterial community in the biofilm was evaluated in the systems. CW-MP achieved the highest COD removals (65 % and 70 %) in both phases. The results for TN and TAN were similar, with CW-P achieving higher efficiency in Phase I. In Phase II, there was no significant dif-ference between CW-P and CW-MP. Regarding total phosphorus removal, CW-P was slightly better than C-MP, with removal efficiencies of 64 % in Phase I and 54 % in Phase II for both systems. The proposed systems could remove organic matter and phosphorus through different processes such as adsorption on the substrate, pre-cipitation, plant uptake, and as a source of carbon and nutrients for microorganisms.