RESUMO
Sustainable sanitation solutions are necessary for promoting public health and environmental security. In this study, on-site domestic wastewater treatment (WWT) systems used for households in rural and peri-urban areas of Brazil were compared in different scenarios from a life cycle assessment (LCA) perspective. The evaluated scenarios represented different practices in wastewater management, such as direct discharge into the soil, rudimentary treatment, septic tank, public sewerage system, and source separation of wastewater streams for water, nutrient, and organic matter recovery. The WWT technologies considered in the proposed scenarios of source-separated wastewater streams were as follows: an evapotranspiration tank (TEvap) and composting toilet for blackwater, a modified constructed wetland (EvaTAC) for greywater, and a storage tank for urine. LCA was performed in this study according to the ISO standards to assess the environmental impacts at both midpoint and endpoint levels. The results show that on-site source-separated wastewater treatment systems with resource recovery result in significant reductions in environmental impacts compared to scenarios with precarious conditions or 'end-of-pipe' solutions. For example, regarding the human health damage category, the scenarios involving resource recovery, including systems such as EvaTAC, TEvap, composting toilet, and urine storage tank, demonstrate significantly lower values (-0.0117 to -0.0115 DALY) compared to scenarios with rudimentary cesspits and septic tanks (0.0003 to 0.001 DALY). We conclude that the focus should be beyond mere pollution aspects and instead concentrate on the benefits of the co-products, which are: avoiding the extraction and consumption of valuable and increasingly scarce raw materials, such as potable water, and production of synthetic fertilizer. Furthermore, it is highly recommended that an LCA of sanitation systems synergistically integrates the WWT process, the constructive aspects, and the resource recovery potential.
Assuntos
Águas Residuárias , Purificação da Água , Humanos , Eliminação de Resíduos Líquidos/métodos , Saneamento , Meio Ambiente , Purificação da Água/métodosRESUMO
In order to know the behaviour and performance of a vertical flow constructed wetland (VF-CW) operating with earthworm, this study evaluated the earthworm presence linked to hydraulic loading rates applied for domestic wastewater treatment. Two VF-CW units (710â cm², 0.75â m deep, with sand as filter media and planted with Heliconia rostrata) operated with a variable hydraulic and organic loadings rates (200â mmâ d-1/123â g COD m-2â d-1; 280â mmâ d-1/186â g COD m-2â d-1; 160â mmâ d-1/94â g COD m-2 d-1). Although the efficiency of COD load removal was similar (around 70%) for both CWs, the efficiency of total nitrogen load removal was around 95% throughout the evaluated period. The nitrification-denitrification process was identified with and without the presence of earthworm. VF-CW with earthworms showed higher hydraulic conductivity values (from 0.11 to 0.14â mâ h-1) compared with the VF-CW wetland without earthworms (0.07-0.09â mâ h-1). This study showed that the use of earthworms in CWs can be associated mainly with a preventive measure of clogging, which requires measures to maintain earthworms inside the bed media. Additionally, the earthworm presence has an ingestion mechanism of organic and inorganic solid particles in wastewater which excretes them as finer particles.
Assuntos
Oligoquetos , Áreas Alagadas , Animais , Nitrificação , Nitrogênio/análise , Eliminação de Resíduos Líquidos , Águas Residuárias/análiseRESUMO
Emerging contaminants are increasingly present in the environment, and their appearance on both the environment and health of living beings are still poorly understood by society. Conventional sewage treatment facilities that are under validity and were designed years ago are not developed to remove pharmaceutical compounds, their main focus is organic and bacteriological removal. Pharmaceutical residues are associated directly with quantitative production aspects as well as inadequate waste management policies. Persistent classes of emerging compounds such as xenobiotics present molecules whose physicochemical properties such as small molecular size, ionizability, water solubility, lipophilicity, polarity and volatility make degradability, identification and quantification of these complex compounds difficult. Based on research results showing that there is a possibility of risk to human and environmental health the presence of these compounds in the environment this article aimed to review the main pharmaceutical and xenobiotic residues present in the environment, as well as to present the most common methodologies used. The most commonly used analytical methods for identifying these compounds were HPLC and Gas Chromatography coupled with mass spectrometry with potential for characterize complex substances in the environment with low concentrations. An alternative and low-cost technology for emerging compound treatment demonstrated in the literature with a satisfactory performance for several types of sewage such as domestic sewage, wastewater and agroindustrial, was the Wetlands Constructed. The study was able to identify the main compounds that are being found in the environment and identify the most used analytical methods to identify and quantify these compounds, bringing some alternatives combining technologies for the treatment of compounds. Environmental contamination is eminent, since the production of emerging compounds aims to increase along with technological development. This demonstrates the need to explore and aggregate sewage treatment technologies to reduce or prevent the deposition of these compounds into the environment.