Infiltration studies on soakaways receiving effluents from single household UASB and septic tank reactors

José Lima De Oliveira Júnior,José Tavares De Sousa,Saionara Alexandre Da Silva,Andressa Muniz Santos

doi:10.5327/z2176-947820170413

Abstract

Clogging tendency has been analyzed in sandy soil soakaways at pilot scale receiving either septic tank effluent (SUM1) or UASB effluent (SUM2) and also at laboratory scale (SUMB1 and SUMB2), in relation to Chemical Oxygen Demand (COD) and accumulated Suspended Solids (SS) concentrations. Clogging was also estimated, by modeling the predicted time for infiltration hydraulic failure. The laboratory results obtained with SUMB1 and SUMB2 confirmed the results obtained for SUM1 and SUM2, showing that soakaways built in sandy soils which receive effluent from septic tanks treating predominantly domestic wastewater tended to clog 58% faster than those receiving UASB effluent. The good correlation observed between the decrease in average infiltration rate and the time of operation suggests that the UASB reactor is a promising technological alternative to septic tanks as a pre‑treatment prior to effluent soil disposal for on‑site decentralized wastewater treatment systems.

Highlights

Wastewater soil disposal is an ancient and well‐estab‐ lished worldwide practice (LOFRANO & BROWN, 2010).(RICE, 1974; OKUBO & MATSUMOTO, 1983; SIEGRIST; MCCRAY; LOWE, 2004).this practice, if not suitably managed, can de‐ grade natural resources by contaminating the soil ma‐ trix or even inducing its collapse (RODRIGUES; MOLINA JÚNIOR; LOLLO, 2010).Anaerobic treatment technologies of domestic waste‐ water prior to soil disposal are widely employed, with simple septic tanks being the most common solution (CRITES & TCHOBANOGLOUS, 1998; PARTEN, 2010)
This paper evaluates the infiltration of domestic wastewater effluents previously treated in a septic tank (ST) and a UASB reactor in relation to the impact of total suspended solids (TSS) and biochemical oxy‐ gen demand (BOD) on soil clogging using experimental soakaways packed with sand, both at laboratory and pilot scale
Using the results obtained at pilot scale, it was possible to create a profile of filling and discharging effluents in the soakaway feed zone (SFZ), as well as the infiltration volume profile for the Soil Infiltration Zone (SIZ) during the 60 minutes period

Summary

Introduction

Wastewater soil disposal is an ancient and well‐estab‐ lished worldwide practice (LOFRANO & BROWN, 2010).(RICE, 1974; OKUBO & MATSUMOTO, 1983; SIEGRIST; MCCRAY; LOWE, 2004).this practice, if not suitably managed, can de‐ grade natural resources by contaminating the soil ma‐ trix or even inducing its collapse (RODRIGUES; MOLINA JÚNIOR; LOLLO, 2010).Anaerobic treatment technologies of domestic waste‐ water prior to soil disposal are widely employed, with simple septic tanks being the most common solution (CRITES & TCHOBANOGLOUS, 1998; PARTEN, 2010). Wastewater soil disposal is an ancient and well‐estab‐ lished worldwide practice (LOFRANO & BROWN, 2010). (RICE, 1974; OKUBO & MATSUMOTO, 1983; SIEGRIST; MCCRAY; LOWE, 2004). This practice, if not suitably managed, can de‐ grade natural resources by contaminating the soil ma‐ trix or even inducing its collapse (RODRIGUES; MOLINA JÚNIOR; LOLLO, 2010). Anaerobic treatment technologies of domestic waste‐ water prior to soil disposal are widely employed, with simple septic tanks being the most common solution (CRITES & TCHOBANOGLOUS, 1998; PARTEN, 2010). Most household on‐site wastewater treatment sys‐ tems depend upon effluent soil infiltration for final disposal (PARTEN, 2010).

Methods

Results

Conclusion