Using Wastewater in Irrigation: The Effects on Infiltration Process in a Clayey Soil

Soil water infiltration is a critical process in the soil water cycle and agricultural practices, especially when wastewater is used for irrigation. Although research has been conducted to evaluate the changes in the physical and chemical characteristics of soils irrigated by treated wastewater, a quantitative analysis of the effects produced on the infiltration process is still lacking. The objective of this study is to address this issue. Field experiments previously conducted on three adjacent field plots characterized by the same clayey soil but subjected to three different irrigation treatments have been used. The three irrigation conditions were: non-irrigated (natural conditions) plot, irrigated plot with treated wastewater for two years, and irrigated plot with treated wastewater for five years. Infiltration measurements performed by the Hood infiltrometer have been used to estimate soil hydraulic properties useful to calibrate a simplified infiltration model widely used under ponding conditions, that were existing during the irrigation stage. Our simulations highlight the relevant effect of wastewater usage as an irrigation source in reducing cumulative infiltration and increasing overland flow as a result of modified hydraulic properties of soils characterized by a lower capacity of water drainage. These outcomes can provide important insights for the optimization of irrigation techniques in arid areas where the use of wastewater is often required due to the chronic shortage of freshwater

An overview of the utilisation of microalgae biomass derived from nutrient recycling of wet market wastewater and slaughterhouse wastewater

Microalgae have high nutritional values for aquatic organisms compared to fish meal, because microalgae cells are rich in proteins, lipids, and carbohydrates. However, the high cost for the commercial production of microalgae biomass using fresh water or artificial media limits its use as fish feed. Few studies have investigated the potential of wet market wastewater and slaughterhouse wastewater for the production of microalgae biomass. Hence, this study aims to highlight the potential of these types of wastewater as an alternative superior medium for microalgae biomass as they contain high levels of nutrients required for microalgae growth. This paper focuses on the benefits of microalgae biomass produced during the phycore-mediation of wet market wastewater and slaughterhouse wastewater as fish feed. The extraction techniques for lipids and proteins as well as the studies conducted on the use of microalgae biomass as fish feed were reviewed. The results showed that microalgae biomass can be used as fish feed due to feed utilisation efficiency, physiological activity, increased resistance for several diseases, improved stress response, and improved protein retention

Development and analysis of the Soil Water Infiltration Global database.

In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements (~76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76% of the experimental sites with agricultural land use as the dominant type (~40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it

Development and analysis of the Soil Water Infiltration Global database

In this paper, we present and analyze a novel global database of soil infiltration measurements, the Soil Water Infiltration Global (SWIG) database. In total, 5023 infiltration curves were collected across all continents in the SWIG database. These data were either provided and quality checked by the scientists who performed the experiments or they were digitized from published articles. Data from 54 different countries were included in the database with major contributions from Iran, China, and the USA. In addition to its extensive geographical coverage, the collected infiltration curves cover research from 1976 to late 2017. Basic information on measurement location and method, soil properties, and land use was gathered along with the infiltration data, making the database valuable for the development of pedotransfer functions (PTFs) for estimating soil hydraulic properties, for the evaluation of infiltration measurement methods, and for developing and validating infiltration models. Soil textural information (clay, silt, and sand content) is available for 3842 out of 5023 infiltration measurements ( ∼ 76%) covering nearly all soil USDA textural classes except for the sandy clay and silt classes. Information on land use is available for 76% of the experimental sites with agricultural land use as the dominant type ( ∼ 40%). We are convinced that the SWIG database will allow for a better parameterization of the infiltration process in land surface models and for testing infiltration models. All collected data and related soil characteristics are provided online in *.xlsx and *.csv formats for reference, and we add a disclaimer that the database is for public domain use only and can be copied freely by referencing it. Supplementary data are available at https://doi.org/10.1594/PANGAEA.885492 (Rahmati et al., 2018). Data quality assessment is strongly advised prior to any use of this database. Finally, we would like to encourage scientists to extend and update the SWIG database by uploading new data to it

BIOPHYSICAL CONTROLS ON RHIZOSPHERE DYNAMICS

Soil structure directly determines important soil physical properties including porosity, hydraulic conductivity, water retention, and mechanical strength. It also indirectly influences almost all biological and chemical processes that occur in soil. Conversely, the development, stability, and dynamics of soil structure are dictated by the very physical, chemical, and biological processes that occur within the structured soil. There is ample empirical evidence showing the effectiveness of wetting and drying in the presence of organic matter in soil aggregation and stabilization. However, the mechanisms that bond the particles together under this process need more investigation. The goal of this dissertation was to understand and develop quantitative description of the role of wetting and drying cycles in presence of exudates in the formation and stabilization of soil aggregates within the rhizosphere.In this dissertation, I (a) developed a new, easy and rapid method to measure the carbohydrate and total carbon concentrations using UV spectrophotometry, (b) examined whether the association between plant root and bacteria exudates with neutral sand particles occurred and defined the mechanism of this association, (c) developed a conceptual/mathematical model describe the soil aggregation mechanism in presence of exudates under multiple wetting and drying cycles, (d) examined the mechanisms that affect rhizosphere water dynamics and whether these dynamics are a result of the osmotic potential induced by root exudates or the soil structure modification that occurred because of these exudates, and (e) developed a mathematical model to quantitatively describe the experimental results of the effect of water potential induced by root exudates on water evaporation rate.This dissertation presented a framework for in-depth understanding on how wetting and drying cycles in the presence of exudates promote soil aggregation and stabilization within the rhizosphere. It also advanced our understanding of the benefits of presence of root exudates in the rhizosphere on water retention and evaporation rate and provided the right-scale physics for high resolution computational modeling of water dynamics around the plant roots and root water uptake

BIOPHYSICAL CONTROLS ON RHIZOSPHERE DYNAMICS

Soil structure directly determines important soil physical properties including porosity, hydraulic conductivity, water retention, and mechanical strength. It also indirectly influences almost all biological and chemical processes that occur in soil. Conversely, the development, stability, and dynamics of soil structure are dictated by the very physical, chemical, and biological processes that occur within the structured soil. There is ample empirical evidence showing the effectiveness of wetting and drying in the presence of organic matter in soil aggregation and stabilization. However, the mechanisms that bond the particles together under this process need more investigation. The goal of this dissertation was to understand and develop quantitative description of the role of wetting and drying cycles in presence of exudates in the formation and stabilization of soil aggregates within the rhizosphere.In this dissertation, I (a) developed a new, easy and rapid method to measure the carbohydrate and total carbon concentrations using UV spectrophotometry, (b) examined whether the association between plant root and bacteria exudates with neutral sand particles occurred and defined the mechanism of this association, (c) developed a conceptual/mathematical model describe the soil aggregation mechanism in presence of exudates under multiple wetting and drying cycles, (d) examined the mechanisms that affect rhizosphere water dynamics and whether these dynamics are a result of the osmotic potential induced by root exudates or the soil structure modification that occurred because of these exudates, and (e) developed a mathematical model to quantitatively describe the experimental results of the effect of water potential induced by root exudates on water evaporation rate.This dissertation presented a framework for in-depth understanding on how wetting and drying cycles in the presence of exudates promote soil aggregation and stabilization within the rhizosphere. It also advanced our understanding of the benefits of presence of root exudates in the rhizosphere on water retention and evaporation rate and provided the right-scale physics for high resolution computational modeling of water dynamics around the plant roots and root water uptake

Phosphorus removal efficiency from wastewater under different loading conditions using sand biofilters augmented with biochar

Treated wastewater is a valuable resource, particularly in countries facing water shortage such as Jordan. Nevertheless, excess nutrients, especially phosphorus, may have detrimental impacts on receiving waterbodies. Treated wastewater in Jordan often exceeds the recommended levels set by the Jordanian Standards for wastewater reuse and discharge. Therefore, it is important to reduce phosphorus loads to acceptable levels before discharge. Biofiltration is a low-cost technology that has shown good potential for wastewater treatment. The performance of biofilters largely depends on the media used. In this study, local sand and sand augmented with biochar prepared from the olive oil processing waste (SBC) were used as filter media for phosphorus removal from clarified secondary treated wastewater. The two media types were tested under different hydraulic and phosphorus loading conditions to simulate shock, flooding, and inundation conditions. The results showed that sand media was more effective in removing phosphorus (90.8 ± 2.6%) than sand amended with biochar (83.3 ± 3.2%). Both media showed resilience under extreme loading conditions. Although phosphorus removal efficiency was negatively affected following the extreme loading events, the observed effects were temporary. The simulated inundation event further showed that the media was able to retain the adsorbed phosphorus. Furthermore, the phosphorus concentration in the effluent remained within the prescribed discharge guidelines at all times.Griffith Sciences, Griffith School of EngineeringNo Full Tex