Treatment of Wastewater With Slow Rate Systems: A Review of Treatment Processes and Plant Functions

Abstract

Land treatment systems constitute a viable alternative solution for wastewater management in cases where the construction of conventional (mechanical) wastewater treatment plants (WWTPs) are not affordable or other disposal options are not available. They have proven to be an ideal technology for small rural communities, clusters of homes, and small industrial units due to low energy demands and low operation and maintenance costs. In addition, slow rate systems (SRS) may be designed using the "zero discharge" concept. The purpose of this article is to review the current trends and developments in the field of SRS, focusing on those systems in which effluent application is based on plant water requirements. Vegetation has an important role in treatment efficiency through its effects on hydraulic loading rate, nutrient removal, and biomass production. In addition, vegetation may affect the fate of trace elements and the degradation/detoxification of recalcitrant organics. Detailed knowledge of the basic processes involved in wastewater treatment and the factors governing the performance of SRS is fundamental for enhancing treatment efficiency and eliminating potential environmental and health risks. Finally, monitoring performance of SRS and adopting the appropriate management strategies are of paramount importance to maintain treatment efficiency over the a long term.

Land Application-Based Olive Mill Wastewater Μanagement

“…However, in terms of the former, this might be unexpected considering great adaptability and tolerance of eucalyptus species to soil salinity [23]. In addition, rainfall during winter period leached effectively salts accumulated during irrigation with effluent of approximately 2 dS/m electrical conductivity- [35].…”

“…These species are widely used in land application schemes due to several desirable attributes, such as adaptability to soil salinity, treatment potential, and biomass production [23], however, their performance in cases of OMW application remains unknown. Moreover, despite the plethora of work dealing with OMW effect on soil properties, little information is available with regard the distinct effect of OMW on the quality and characteristics of soil solution.…”

Carbon Turnover during Effluent Application to the Land: A Potential Role for Vegetation?

“…Many factors have been reported to affect the turnover of C in soils including the composition of organic substrate, soil properties and management, climatic conditions, and vegetation [11,12]. With regard to the effect of vegetation, its role has not been investigated in land treatment systems although indirect impacts have been proposed through its effect on effluent application rate and litter deposition [1]. Recent studies have provided evidence that plant species may affect the turnover of C in the soil through its effects on litter composition and rhizodeposition as well as microbial community composition and activity [5,[13][14][15].…”

“…Effluent application to the land constitutes a widespread practice and it contributes to the further treatment of effluents and the beneficial recycling of water and nutrients [1]. Depending on the pre-treatment level and composition, effluent application onto land may result in relatively high amounts of carbon (C).…”

Contribuciones para el tratamiento de aguas residuales con sistemas alternativos de bajo coste. Aplicaciones para el desarrollo en poblaciones reducidas y cooperación

“…La deposición al suelo a modo de abono ha sido el método más antiguo de aprovechamiento, pero su utilización incontrolada puede tener importantes impactos negativos en el entorno debido principalmente a la excesiva carga orgánica y microbiana de estos residuos y a la disolución y transporte de algunos metales pesados (Paranychianakis et al, 2007).Este aprovechamiento sigue siendo en la actualidad una importante forma de integrar los residuos en el ciclo de nutrientes. Un ejemplo son los fangos procedentes de los tratamientos de depuración, que han sido procesados para minimizar estos riesgos.…”