Prattrosario5346

For the first time, the operational feasibility of the solar photo-Fenton process at neutral pH in continuous flow has been tested for three consecutive days. The aim of the treatment was to remove of contaminants of emerging concern (CECs) from wastewater treatment plant secondary effluents. To this end, a 5 cm-deep raceway pond reactor was run in continuous flow mode and the degradation of the CECs present in real secondary effluents was monitored at their natural concentrations. To keep dissolved iron at neutral pH, ethylenediamine-N,N'-disuccinic acid (EDDS) was used to form the complex Fe(III)EDDS as an iron source for the photo-Fenton reactions. At pilot scale the effects of the Fe(III)EDDS molar ratio (11 and 12) and hydraulic residence time (HRT) (20 and 40 min) on CEC removal were studied. The best operating condition was 20 min of HRT, giving rise to a treatment capacity of 900 L m-2 d-1 with CEC removal percentages of around 60%. The reactant concentrations were 0.1 mM Fe(III)EDDS at a 11 M ratio and 0.88 mM H2O2. Under these operating conditions, the short-term stability of the process was also demonstrated, thus pointing out the potential of this solar technology as a tertiary treatment. Drying is one of the treatment techniques used for the dual purpose of safe disposal and energy recovery of faecal sludge (FS). Limited data are available regarding the FS drying process. In this paper the drying properties of FS were investigated using samples from ventilated improved pit (VIP) latrines and urine diversion dry toilets (UDDT) and an anaerobic baffle reactor (ABR) from a decentralized wastewater treatment systems. Moisture content, total solids content, volatile solids content, water activity, coupled thermogravimetry & differential thermal analysis (TGA-DTA) and calorific value tests were used to characterize FS drying. Drying kinetics and water activity measured at different moisture content during drying (100 °C) were similar for the samples from different on-site sanitation facilities. Experimental heat of drying results revealed that FS requires two to three times that of the latent heat of vaporization of water for drying. Drying temperature was more significant than the sludge source in determining the final volatile solids content of the dried samples. This was reinforced by the dynamic TGA that showed considerable thermal degradation (2-11% dry solid mass) near 200 °C. Below 200 C, the calorific value of the dried samples exhibited no significant difference. The average calorific values of VIP, UDDT and ABR samples at 100 °C were 14.78, 15.70, 17.26 MJ/kg dry solid, respectively. This suggests that the fuel value of FS from the aforementioned sanitation facilities will not be significantly affected by drying temperature below 200 °C. Based on this study, the most suitable temperature for drying of FS for a solid fuel application was found to be 150 °C. Soil organic carbon (SOC) storage and carbon dioxide (CO2) emission under different tillage methods in a crop residue-returned farming system may not be consistent with result from studies of the usual tillage researches because crop residues are important carbon sources with significant effects on soil carbon input and output. learn more Herein, we address a knowledge gap over the "hot spot" research on tillage practices on SOC storage and CO2 emission in crop residue-returned farming systems. In this study, a long-term (2007-2019) field experiment was conducted, and the crop residues were returned to the soil after harvest; then, three tillage methods were conducted no tillage (NT), subsoiling tillage (ST), and a moldboard plow tillage (CT). Our results showed that in the crop residue-returned farming system, NT and ST still showed advantages of lower CO2 flux compared with CT, as well as a reduced average CO2 flux of 14.5% and 8.5%, respectively, over a two-year average. The results of our long-term study suggest that the NT had advantages of SOC accumulation. In addition, as of June 2018, NT increased SOC stocks with 5.85 Mg hm-2 at a 0-60-cm soil depth compared with CT, whereas no significant difference was found between ST and CT. Overall, adopting NT in a crop residue-returned farming system improved SOC storage to 5.85 Mg hm-2 after 11 years as well as decreased CO2 flux by 14.5% in comparison with CT, which is meaningful in improving soil carbon pool and decreasing soil CO2 emission during agriculture production. Dredging is a globally important aquatic system management activity, used for navigation improvement, contamination removal, aggregate production and/or flood risk mitigation. Despite widespread application, understanding of the environmental effects of some dredging types remains limited. Field campaigns in 2016 and 2017 in the River Parrett estuary, UK, therefore investigated the geomorphic and physicochemical effects of Water Injection Dredging (WID), a poorly studied hydrodynamic dredging technology. WID, applied to restore channel capacity for the maintenance of flood water conveyance in the tidal River Parrett, influenced surface elevations but not grain-size characteristics of dredged bed sediments. Topographic alterations due to the 2016 WID operation were short-lived, lasting less than 10 months, although benefits of the 2017 WID operation, in terms of volumetric change, outlasted the ≈12-month study period. Dredging had a significant impact on water physicochemistry (pH, dissolved oxygen, total suspations of WID as a flood risk management tool in estuaries and rivers. The open disposal of groundwater treated soil containing arsenic (As) and iron (Fe) is a critical environmental issue in developing countries like Bangladesh. The current study attempts to use the arsenic-iron soil (AIS) as partial replacement of aggregate for preparing the sustainable solid mortar composite. Four dosages (2.5-10%) of AIS were applied as the substitution of fine aggregate for finding the optimum quantity of AIS, justifying by strength and nominal leaching content of As and Fe in pH solution 4.0 and 7.0 and curing temperatures of 25, 30, and 35 °C. Also, the external surfaces of solidified matrices were modified with cement grouting solution and cement plaster to resist the migration of concerned contaminants to curing media. The analytical compressive and flexural strength results showed that the solid mortars blended with 2.5 and 5% AIS obtained over 80% of the control specimens throughout the testing ages. Moreover, the study found that 5% AIS bearing hardened composition with exterior cement plaster exhibited the releasing contents of As and Fe below the drinking water standard in both pH solutions and adopted three curing temperatures, which is safe as well as economical to use as a construction material.