Long term effect of irrigation with the treated sewage effluent on some soil properties of Al-Hassa Governorate, Saudi Arabia

AbstractA case study was undertaken to assess the long-term effect of sewage irrigation on some soil properties and heavy metals concentrations in the soils of the date palm at Al-Hassa Governorate, Saudi Arabia. Eighty-two surface soil samples were collected from the studying area. Half of it was collected from an area irrigated for more than 13years with treated sewage effluent. Meanwhile the rest of soil samples were collected from an area irrigated with well water. Furthermore, samples from sewage effluents and well water used for irrigation were collected and analyzed mainly for their chemical composition and their metal contents. The obtained results pertaining irrigation water analysis indicated that sewage effluents were found to contain higher content of Pb, Zn, Cu, Co, Cr, As, Cd, Fe, Mn and Ni compared to well water. On the other hand data emphasized the role of sewage effluent irrigation on increasing heavy metals as well as organic matter contents in the soil samples when comparing with the respective values found in the soil irrigated with well water. The soil salinity ranged from 3.58 to 20.7dSm−1 with an average of 7.9dSm−1 due to irrigation with well water. While the respective soil salinity due to irrigation for long period with the treated sewage effluent ranged from 2.5 to 3.69dSm−1 with an average of 2.8dSm−1. There was an increase in organic matter content ranging from 17% to 30% in sewage-irrigated soil samples as compared to well water-irrigated ones. On an average, the soil pH dropped by 0.3U as a result of sewage irrigation. Long term sewage irrigation resulted in significant build-up of total concentration of Zn (130%), Pb (55%), Fe (82%), Ni (84%), Mn (30%), Cu (40%), Cr (75%), Co (78%) and As (67%) in sewage-irrigated soil samples over adjacent well water-irrigated soil samples

Characteristics of landfill leachates and bio-solids of municipal solid waste (MSW) in Riyadh City, Saudi Arabia

The liquid and bio-solids (landfill sediments) product from landfills has many toxic substances, which may adversely affect on the environmental health. Thus in order to have a better management of characteristics of Riyadh landfill leachates, 80 representative landfill leachate samples were collected and analyzed from February to May 2008. The analysis of landfill leachates includes pH, ECw, concentrations of soluble ions, chemical oxygen demand (COD), total suspended solids (TSS), and heavy metals contents. The obtained results showed that the landfill leachates are characterized by high concentrations of COD (13,900–22,350) mg L−1, TSS of (2280–8912) mg L−1, ECw values of (42.5–58.3) dS m−1 but the pH values ranged 5.49–6.32. Moreover, the leachates had higher concentrations of soluble Na+, K+, Ca2+, Mg2+, Cl−, HCO3- and SO42-. In addition, the leachates contained Fe, Mn, As, Ni, Cr, Zn and Cu in concentrations equivalent to: 104, 11.0, 1.4, 0.6, 0.25, 0.2 and 0.14 mg L−1, respectively. While in the bio-solids (landfill sediments) the average content of Cd, Cr, Cu, Fe, Mn, Mo, Ni and V reached to 10, 242, 234, 48,608, 190, 18, 166 and 24 mg kg−1. The relatively higher variations between the upper and lower limits (maximum and minimum values) of the studying parameters lead to conclude that it is essential to conduct a long-term monitoring program to obtain representative information and this fluctuation should be considered when operating the leachate treatment plant

Spatial variability for some properties of the wastewater irrigated soils

Composite surface soil samples (236 samples) were collected from three fodder farms irrigated for a long period with the treated sewage effluents or well water through a center pivot system. The soil of the 1st farm was loamy sand in texture while it was sandy loam for the other two farms, all were calcareous containing more than 10% of (CaCO3). The average values of EC for the 1st, 2nd and 3rd farms showed to be 3.48, 2.20 and 2.21 dS m−1, respectively. The concentration of Zn was found to be 28.87 mg kg−1 in the 1st farm, while it was 45.96 and 19.51 mg kg−1 in the 2nd and 3rd farms, respectively. The Zn, Cu, Fe and Ni concentrations were higher in the farms irrigated with the treated sewage effluent than their concentrations in those irrigated with well water. The values were 28.87, 16.95, 4225, and 72.26 mg kg−1 for Zn, Cu, Fe & Ni in 1st farm and 42.4, 60.5, 11215, and 180 mg kg−1 for the 2nd farm. The Pb in the soil of the 1st, 2nd and 3rd farms reached 63.01, 37.10 and 27.69 mg kg−1, respectively. It can be concluded that all soil properties except pH had high coefficients of variation, indicating strong variability over space. The data of geo-statistical analysis showed that only TDS and ESP in the 1st farm as well as OM in the 2nd farm had weak spatial dependency while other properties had moderate or strong spatial dependency. Moreover, the TDS and CaCO3 parameters of the 1st and 2nd farms had stronger nugget effects