The Effect of Soil Tillage Equipment on the Recharge Capacity of Infiltration Ponds

Abstract

The Dan Region Reclamation Project (Shafdan) reclaims ~125 millions of cubic meters per year (Mm3/year) of treated wastewater from the Tel Aviv Metropolitan area. Following secondary treatment, the effluent is recharged into a sandy aquifer for soil aquifer treatment (SAT). Over the past three years, a decrease in recharge capacity was noticed. Several operational causes were considered including reservations regarding the tillage procedure of recharge ponds. Tillage of the recharge ponds facilitates aeration, breaking surface crusts and the removal of vegetation. The procedure includes deep (40–60 cm) plowing and shallow (10–20 cm) sweep-knives (SK) cultivator or discus. In this research, the existing tillage equipment was compared to a new equipment, which includes a deep subsoiler and a chisel-knives (CK) cultivator. The effects of each tool on the infiltration rate (IR), recharge capacity, and soil compaction were examined. The results suggest a significant improvement in the recharge capacity, up to 95% and 15% on average following subsoiler and CK cultivator treatments, respectively, with respect to the existing plowing treatment. In addition, the depth of the compacted soil layer increased from ~30 to ~55 cm after subsoiler treatment. It seems that this shallow layer, developed under an improper tillage regime, played a major role in the reduction of the recharge capacity. Essential understanding of other operational factors such as drying periods, preparation of the field, and soil micro-topography was also achieved.

A Reliable U-trough Runoff Collection Method for Quantifying the Migration Loads of Nutrients at Different Soil Layers under Natural Rainfall

“…The subsurface runoff (SSR), as an essential part of runoff, presents important influences on soil nutrients leaching loss in the watershed [4]. The factors influencing SSR include soil physical and chemical properties [5,6], geobiont [7,8], plant roots [9,10], ground slope [11,12] and roughness [13,14], climate including rainfall [15,16] and freeze-thaw [17], surface coverage [18,19], and farming practices [20,21]. However, such complex and diverse factors make soil nutrients' underground loss difficult to measure directly [22,23].…”

From managed aquifer recharge to soil aquifer treatment on agricultural soils: Concepts and challenges

“…The intermittent operation scheme and the water quality are the two characteristics of SAT that distinguish it from most MAR methods. Flooding and drying cycles are crucial to SAT operation as they enable the aeration of the soil underneath the SAT basin and maintain steady infiltration rates (Negev et al, 2020). During the treatment process, effluent percolates through the vadose zone while being subjected to contaminant removal mechanisms, such as physical filtration, biodegradation, adsorption, chemical precipitation, ion exchange, and dilution (Fox et al, 2001).…”

“…SAT is a globally practiced aquifer rehabilitation technique (Table 2). Israel possesses one of the largest wastewater treatment facilities worldwide (Dan Regional Reclamation Project, aka Shafdan), accompanied by SAT facilities capable of very high effluent loading rates (around 120 Mm 3 /year (Negev et al, 2020)) (Aharoni et al, 2011;Icekson-Tal et al, 2003). The United States hosts many SAT facilities (e. g., in Arizona, California, Colorado, Florida, Massachusetts, Michigan, Montana, New Jersey, New York, and South Dakota) (Crites et al, 2006;Sharma and Kennedy, 2017).…”

“…Mechanical treatment of the soil in the SAT basin, tillage, is a practice exclusive to SAT compared to other MAR systems. Tillage in the infiltration basins allows aeration of the upper soil layer (Negev et al, 2020), by removing the clogging layer (known as "cake"), caused by biological and physical deposition (Aharoni et al, 2011), which alleviates oxygen stress in the vadose zone. Moreover, tillage breaks the surface crusts and vegetation that form on the infiltration basin's surface (Negev et al, 2020).…”

Revisiting Soil Aquifer Treatment: Improving Biodegradation and Filtration Efficiency Using a Highly Porous Material

“…However, increasing WW volumes and escalating real estate prices around urban areas highlight the need to re-engineer the SAT process and maximize the recharge capacity without sacrificing the effluent quality [22]. Therefore, efforts are being made to maximize the percolation flux by: (1) Studying the spatiotemporal infiltration dynamics across the ponds using hydro-geophysical tools [23]; (2) releasing air which is entrapped below the wetting front [24]; (3) improving tillage technologies to effectively break the biocrust and maintain high infiltration rates in the ponds [25]; and (4) improving the SAT management by optimizing the length of the wetting and drying cycles.…”