Effect Of Long-term Wastewater Irrigation Research Articles

The Effect of Wastewater Irrigation on the Activity of Soil Microorganisms

Introduction: The use of wastewater for irrigation in arid and semi-arid regions of the world is increasing. This study aimed to evaluate the effects of wastewater on the microbial activity of irrigated soils using the enzymatic activity of soil microorganisms. Materials and Methods: In this study, for soil irrigation, the secondary effluent of the Isfahan municipal wastewater treatment plant was used. As a control, tap water that has no microbial load was also used. Soil samples were collected in two stages, before and immediately after irrigation. All samples were collected in sterile bags, transferred immediately to the laboratory for physicochemical and microbiological tests. Soil samples were analyzed for the amounts of enzymatic activity (Fluorescein Diacetate (FDA) and dehydrogenase), electrical conductivity (EC), oxidation-reduction potential (ORP), and pH. Results: The EC levels before and after irrigation with tap water was 231.2 and 260.63 µs.cm-1, respectively, which was significantly different from levels of wastewater-irrigated soil (P < 0.05). pH in the two types of used water before and after irrigation was 6-8 and 7-8, respectively. No significant difference was observed in the levels of FDA, dehydrogenase, ORP, and microbial population in samples irrigated with water and wastewaters (p > 0.05). It was found that there is a significant relationship between bacterial density and FDA (P < 0.05). Conclusion: The results of the study showed that irrigation with wastewater has no significant effect on the microbial activity of irrigated soil. Because of the short-term wastewater irrigation in the present study, however, further investigation is needed to evaluate the effect of long-term wastewater irrigation on the microbial and physicochemical quality of soil.

Comparative Study on Soil Microbial Diversity and Structure Under Wastewater and Groundwater Irrigation Conditions.

Wastewater (WW) irrigation to agricultural soils is one of the most economical and effective water-saving strategies. The effects of WW irrigation on soil microbial communities have gained increasing focus as these effects are not well understood. In this study, the effects of WW and groundwater (GW) irrigation on microbial diversity and structure were compared using the high-throughput sequencing analysis of 16S rDNA amplicons. Soil samples irrigated by WW for several decades and maize soil (loamy) samples irrigated by GW were collected from Luancheng Town, Shijiazhuang City, China. Compared to the GW groups, WW groups exhibited non-significant soil bacterial community abundance at the 0-20 and 20-40cm depths. WW irrigation significantly altered the bacterial community composition and structures compared to GW irrigation. The relative abundance of Proteobacteria and Firmicutes increased in WW irrigated soil, while Actinobacteria decreased. Moreover, 14 significantly abundant biomarkers from Proteobacteria and Firmicutes that corresponded with WW irrigation were identified. Additionally, WW irrigation enriched some KEGG pathways that corresponded with metabolism and human diseases. The physical and chemical properties of WW irrigated soil may shape the compositions and structures of soil bacterial communities. The findings of this study illuminated the effects of wastewater irrigation on microbial characteristics, which is important for estimating the effects of long-term wastewater irrigation on soil environmental health.

The effect of long-term wastewater irrigation on the botanical composition of meadow sward, yield and nutritional value of hay

The effect of long-term wastewater irrigation on the botanical composition of meadow sward, yield and nutritional value of hay

Effect of long-term wastewater irrigation on the quality of alluvial soil for agricultural sustainability

To evaluate the effects of using wastewater in alluvial soil irrigation for long periods on soil quality (SQ), Bahr-Elbaqar study location was chosen (32° 15′ to 32° 09′ E and of 30° 58′ to 31° 07′ N). The SQ assessment was carried out using 15 soil features belonging to seven soil locations; six irrigated with wastewater for different periods and one control location irrigated with freshwater. The soil quality index (SQI) of the seven locations was calculated using either total data set (TDS) or minimum data set (MDS) methods. The principal component analysis was utilized to recognize soil characteristics for the MDS. The results indicated that using wastewater in irrigation negatively influenced the soil salinity status represented by electrical conductivity (EC) exchangeable sodium percent (ESP), and sodium adsorption ratio (SAR) by 62–107%, 17–52% and 31–80%, respectively. Available heavy metals (Pb, Cd, Cu and Ni) increased with increasing the irrigation periods and the highest mean values were in location 6 that been irrigated for >42 years implying an adverse and degrading influence on soil quality. In contrast, irrigation with wastewater enhanced some soil indicators including organic matter (OM), total N (T-N), available P, K (A-P and A-K), and cation exchange capacity (CEC) indicating a constructive and enhancing influence on soil quality. The contributions of pH, EC, ESP, A-P, A-Cd and OM were the highest and chosen as MDS to calculate MDS-SQI. Most of the examined area classified in Moderate class either using the TDS or MDS.

Effects of long-term wastewater irrigation on soil physical properties and performance of selected infiltration models in a semi-arid region

ABSTRACTIn many arid and semi-arid countries, wastewater irrigation is becoming a common practice in agriculture. In this study, the effect of long-term (40 years) wastewater irrigation on selected physical and hydraulic properties of soil in different parts of a landscape was investigated. The performance of some infiltration models, including Philip (Ph), Kostiakov (Kos), Kostiakov-Lewis (Kos-L), Horton (Ho), Huggins and Monke (Hug-M), and linear and nonlinear Smith-Parlange (S-P(L) and S-P(NL)), was compared. This study was performed in the Urmia region, Iran, where flooding wastewater irrigation has been practised for at least 40 years. Five paired sites, each of which contained a measurement location at the wastewater-irrigated (WWI) and adjacent control area were studied. Accuracy of the infiltration models was evaluated using several statistical criteria, including root mean square error (RMSE) and Akaike information criterion (AIC). The models were classified into groups using cluster analysis based on level of similarity in their performance. The cumulative water infiltration into soils after 1 h (I1h) was calculated using the selected most accurate models and introduced so as to use only one term to compare the infiltration behaviour of soils. Based on RMSE and AIC, the performance of the Ph, Ho, Kos and Kos-L models was considerably better than that of Hug-M, S-P(L) and S-P(NL). The ranking of the models in terms of their AIC values was: Kos-L > Ho > Kos > Ph > S-P(L) > Hug-M > S-P(NL). The models were classified into two distinct groups. The similarity among Ph, Ho, Kos and Kos-L models was more than 80% and for Hug-M, S-P(L), and S-P(NL) models, it was more than 79%. However, the similarity between these two groups of models was less than 58%.Editor M.C. Acreman; Associate editor not assigned

The effect of long-term wastewater irrigation on accumulation and transfer of heavy metals in Cupressus sempervirens leaves and adjacent soils

Wastewater reuse for agriculture is an important management strategy in areas with limited freshwater resources, yielding potential economic and environmental benefits. Here the effects of long-term irrigation with wastewater on the nutrient contents of green and senesced leaves of Cupressus sempervirens L. were assessed for three planted forests in Egypt. Stoichiometric ratios, transfer factors for nutrients from soil to plant and enrichment factors in contaminated soils were estimated and compared to a ground water irrigated control site. Under wastewater irrigation, C. sempervirens transferred most of the estimated nutrients, particularly heavy metals, from green to senesced leaves. This could be a self-protecting mechanism under continuous wastewater irrigation. The accumulation of four metals (Zn, Mn, Cu and Cd) with transfer factors>1 for wastewater-irrigated trees, indicated the ability for metal accumulation of C. sempervirens. Stoichiometric ratios decreased under wastewater irrigation compared to the control site and global trends, which suggests nutrient disorders in these plants. The values of enrichment factors in the wastewater-irrigated soils showed remarkable availability and distribution of metals. Decreased resorption of metals by senesced leaves of C. sempervirens will add considerable amount of these metals to the soils, which will likely have adverse affects on the desert ecosystem components.

Effect of Long-Term Wastewater Irrigation on Potential Denitrification and Denitrifying Communities in Soils at the Watershed Scale

Wastewater irrigation mitigates the problem of water shortage but leads to the potential accumulation of pollutants and causes corresponding changes in denitrifying communities and denitrification, hence the potential ecological risk of long-term wastewater irrigation should not be overlooked. We investigated the relative contributions of different environmental factors to the abundance and diversity of denitrifying communities harboring nirK, nirS, and nosZ genes and the relative importance of these biotic and abiotic variables in potential denitrification activity (PDA) in soils with wastewater irrigation for around 25 years at a large watershed scale. Results showed that soil physicochemical properties, pollutants, including heavy metals and PAHs, and vegetation are the major factor groups influencing the abundance and structure of the three denitrifying communities and PDA. NirK-, nirS-, or nosZ-harboring denitrifiers responded in different manners to environmental changes, and were mainly influenced by substrate concentration, carbon source, or pollutants, respectively. The structure of the three denitrifying communities was more relevant to the environmental changes than their abundance. Conversely, the abundance, rather than diversity, was correlated with PDA. Pollutants and vegetation could affect PDA by both direct and indirect paths through soil physicochemical properties including pH, carbon and nitrogen sources, or through the abundance of denitrifying functional genes. The abundance of denitrifying functional genes is a valuable index that integrates potential activity and various environmental factors, and is therefore a good predictor of denitrification in the presence of environmental changes.

Effects of Long-Term Wastewater Irrigation on Soil Properties

ABSTRACT The use of wastewater for irrigation is increasingly being considered as a technical solution to minimize soil degradation and to restore nutrient contents of soils. This study describes changes in soil and plant nutrient contents after long-term irrigation with wastewater. Application of wastewater increased salinity and decreased pH. Several beneficial changes were observed including an increase in organic matter, N, concentrations of major cations and heavy metals of soils. Wastewater increased N, P, Fe, Mn, Zn, Cu, B, Mo and Cd contents of cabbage (Brassica olerecea var. Capitate cv. Yalova-1) and potato (Solanum tuberosum) plants. In order to avoid undesirable side effects due to salinity and toxic concentrations of metals from the application of wastewater to soil, it is necessary to determine the effects of wastewater concentration in long-term periods.