Reviewing factors affecting the effectiveness of decentralised domestic wastewater treatment systems for phosphorus and pathogen removal

Abstract

a b s t r ac tEnvironmental pollution and risks to human health can result from diffuse sources of pollution originating from decentralised wastewater treatment systems (DWTS). In particular, phosphorus pollution can lead to eutrophication and the downgrading of the quality of water bodies, for example, under the Water Framework Directive in the EU, and pathogen pollution can result in increased risks of human exposure to pathogens and impacts on industries such as shellfish growing and tourism. The study reported in this paper reviews the effectiveness of various DWTS in removing phosphorus and pathogens from on-site systems. It was found that DWTS are typically not designed to specifically treat these pollutants, and the most common type of DWTS, septic tanks, provides only basic treatment. Additional treatment such as filtration-based or wetland systems must be used to achieve desired levels of treatments. The performance of these systems is affected by site-specific conditions, such as input load and sources, and climatic conditions, and as such operational characteristics and treatment measures must be designed to take account of these factors.

Removal of Pathogens in Onsite Wastewater Treatment Systems: A Review of Design Considerations and Influencing Factors

“…For each publication, the log 10 reduction and removal efficiency of different indicators were calculated using Equations (1)-(3) when the studies expressed the concentrations of pathogens using logarithmic notation. Log 10 reduction = log 10 C in C out (1)…”

“…OWTSs hold the promise to eliminate pathogens and other contaminants while offering the benefits of low cost and wide application [3,9,10]. However, few case studies or reviews have focused on the microbiological quality of effluents, and how operation conditions and design factors may affect the removal of pathogens (e.g., system configuration, filtration media, and seasonal impact, etc.).…”

Comparison of removal efficiency of pathogenic microbes in four types of wastewater treatment systems in Denmark

“…It is known that these systems could act as excellent bacterial sinks through a combination of complexes physical, chemical and biological factors that actively participate in the reduction of the number of bacteria present in water (Vymazal, 2005;Wu et al, 2016). In the last 15 years, significant resources have been invested to improve the understanding of the mechanisms involved in the removal of microbes at decentralized systems (Arias et al, 2003;Hansen et al, 2004;Ibekwe et al, 2003;Karim et al, 2004;Vacca et al, 2005;Winward et al, 2008;Adrados et al, 2014;Morató et al, 2014;Wu et al, 2016;Alexandros and Akratos, 2016;Akunna et al, 2017). However, there is still a lack of information from comparative studies evaluating the removal of microbes between natural wastewater treatment systems actively working during long-term operation periods.…”

Solids removal from Balneo peat extracts

“…The cake formed by solids from peat was highly compressible, which caused filtration, the most common method to heterogeneity removal [18,19] has failed.…”