Comparison between Analytical Equation and Numerical Methods for Determining Shear Stress in a Cantilever Beam

A three meter-length cantilever beam loaded with a concentrated load at its free end is studied to determine shear stresses. In the present study, three cross sections are considered: rectangle (R); I, and T. The study presents a comparison of maximum shear stresses obtained by means of two methods: classical analytical equation derived by Collingnon, and finite element method (FEM) software. Software programs ANSYS and SAP2000 were used. The results show difference between the maximum shear stresses obtained by the analytical equation and the software, being the last is always higher. The average differences for ANSYS and SAP2000, independently of the cross section, were 12.76% and 11.96%, respectively. Considering these differences, correction factors were proposed to the classical analytical formula for each cross section case to obtain more realistic results. After the correction, the average differences decrease to 1.48% and 4.86%, regardless of the cross section shape

Health Risk Associated with Some Trace and Some Heavy Metals Content of Harvested Rainwater in Yatta Area, Palestine

Rainwater is considered a dependable source for domestic purposes within rural areas in Palestine. Harvested rainwater stored in cisterns is used to leverage deficits from municipal water supplies. Harvested rainwater in areas surrounded with industrial and agricultural activities is usually contaminated with heavy and trace metals. To study the effects of human exposure to heavy and trace metals, 74 harvested rainwater samples of rain-fed cisterns were collected from different localities in the Yatta area of Palestine in the months of January and February of 2016. The water samples were analysed for Ca, Mg, Al, Fe, K, Na, Ag, Li, Co, Ba, Bi, Sr, Ga, V, Rb, Mo, Beand Tl elements utilizing ICP-MS (inductively coupled plasma mass spectrometry). The selected trace metals were found within the concentration limits of the acceptable values, in accordance with WHO and Palestinian standards, except for K and Al, which were found above the allowed limits. The potential risks of the selected trace metals on the health of the local residents, as well as the possible sources of such heavy metals, were also studied. The Chronic daily intake (CDI) of each metal and health risk indexes (HRI) were calculated for both adults and children residents. The oral ingestion pathway was studied, including exposure via drinking water. The values for CDI were found in the descending order of: Ca > Mg > Na > K > Sr > Fe > Al > Ba > Li > V > Rb > Ag > Mo > Ga > Co > Bi > TI > Be. The values of HRI were below 1 for most of the selected heavy metals, expect for Li for children, indicating potential health risk. The study also predicted that the local residents have a higher chance of developing cancer in their lifetime, especially children, with respect to the carcinogenic risk (CRing) values for Na, Mg, Al, Ba, K, Ca, Fe and Sr, which were greater than standardized limits (>106). The rest of the selected elements were within the acceptable limit in the five different studied locations. Furthermore, univariate, multivariate and statistical analysis depending on one-way ANOVA, inter-metal correlation, cluster analysis (CA) and principal component analysis (PCA) results revealed that geogenic and anthropogenic activities were major sources of drinking water contamination by heavy metals in the Yatta area.The authors would like to thank Yatta municipality for helping in samples collection, the households that facilitated our sampling, and Al-Quds University where water samples were analysed

Studies on Weathered Waterborne Treated Wood: Leaching of Metals during Service and Metals Based Detection upon Recycle

Weathered waterborne treated wood is believed to behave differently than new wood during service regarding the loss of its metallic-based preservatives. Also, weathered preserved wood should be separated from the unpreserved wood upon recycle. The first objective of this dissertation was to evaluate losses from weathered CCA-treated wood samples at different retention levels under normal field conditions and to compare leaching to new ACQ (as alternative to CCA). Results showed that arsenic leached at a higher rate than chromium and copper in all CCA treated wood samples, while copper leached the highest from the ACQ sample. Overall results suggest that the leaching rate of metals on a percent basis from in-service pressure treated wood may increase as the wood weathers; however due to lower retention levels of the metals in the wood as it ages the yearly mass of metals lost would be at similar or at lower quantities in comparison to new treated wood. The second objective was to evaluate the use of automated X-ray fluorescence (XRF) systems for identifying and removing As-based and Cu-based treated wood within the recovered wood waste stream. A full-scale online automated XRF-detection, conveyance and diversion system was used for experimentation. At the different applied feeding rates and belt speeds, online sorting efficiencies of waste wood by XRF technology were high (\u3e70% for both treated wood and untreated wood). The incorrectly diverted pieces of wood were attributed to deficiencies in the wood conveyance systems and not to deficiencies in the XRF-based detection. Online sorting was shown to sort wood which would meet the residential soil cleanup target levels in Florida when an infeed is composed of 5% of treated wood pieces. Comparisons with other sorting methods show that XRF technology can potentially fulfill the need for cost-effective processing at large wood recycling facilities (\u3e 30 tons per day). Management of weathered CCA-preserved wood, due to its continuity of leaching metals and the need to remove it upon the recycle of wood, will likely continue until complete banning and removal from the environment, a process that may extend up to the next century

Online sorting of recovered wood waste by automated XRF-technology: Part II. Sorting efficiencies

Sorting of waste wood is an important process practiced at recycling facilities in order to detect and divert contaminants from recycled wood products. Contaminants of concern include arsenic, chromium and copper found in chemically preserved wood. The objective of this research was to evaluate the sorting efficiencies of both treated and untreated parts of the wood waste stream, and metal (As, Cr and Cu) mass recoveries by the use of automated X-ray fluorescence (XRF) systems. A full-scale system was used for experimentation. This unit consisted of an XRF-detection chamber mounted on the top of a conveyor and a pneumatic slide-way diverter which sorted wood into presumed treated and presumed untreated piles. A randomized block design was used to evaluate the operational conveyance parameters of the system, including wood feed rate and conveyor belt speed. Results indicated that online sorting efficiencies of waste wood by XRF technology were high based on number and weight of pieces (70–87% and 75–92% for treated wood and 66–97% and 68–96% for untreated wood, respectively). These sorting efficiencies achieved mass recovery for metals of 81–99% for As, 75–95% for Cu and 82–99% of Cr. The incorrect sorting of wood was attributed almost equally to deficiencies in the detection and conveyance/diversion systems. Even with its deficiencies, the system was capable of producing a recyclable portion that met residential soil quality levels established for Florida, for an infeed that contained 5% of treated wood

Online sorting of recovered wood waste by automated XRF-technology. Part I: Detection of preservative-treated wood waste

Waste wood is frequently contaminated with wood treatment preservatives including chromated copper arsenate (CCA) and alkaline copper quat (ACQ), both of which contain metals which contaminate recycled wood products. The objective of this research was to propose a design for online automated identification of As-based and Cu-based treated wood within the recovered wood waste stream utilizing an X-ray fluorescence (XRF) system, and to evaluate the detection parameters of such system. A full-scale detection unit was used for experimentation. Two main parameters (operational threshold (OT) and measurement time) were evaluated to optimize detection efficiencies. OTs of targeted metals, As and Cu, in wood were reduced to 0.02 and 0.05, respectively. The optimum minimum measurement time of 500 ms resulted in 98%, 91%, and 97% diversion of the As, Cu and Cr mass originally contained in wood, respectively. Comparisons with other detection methods show that XRF technology can potentially fulfill the need for cost-effective processing at large facilities (>30 tons per day) which require the removal of As-based preservatives from their wood waste stream

Transport and interaction of arsenic, chromium, and copper associated with CCA-treated wood in columns of sand and sand amended with peat

Laboratory column leaching experiments were conducted to investigate the transport and interaction of As, Cr, and Cu associated with CCA-treated wood in sand with and without peat amendment. Results showed that leaching behavior of As, Cr, and Cu in these substrates were totally different. Substrate characteristics and microorganism activity posed distinct effects on the transport and transformation of these three elements. Arsenic was rapidly leached out from the columns with or without the amendment of peat, while Cr remained in all columns during the entire experimental period (215 d). Copper was leached out only in the substrate column without peat. The presence of microorganism clearly facilitated the transport of As, while it did not show obvious effects on the transport of Cr and Cu. Interactions among these three elements were observed during the processes of adsorption and transport. The adsorption of Cu on soil was enhanced with the adsorption of As, likely caused by a more negatively charged soil surface because of As adsorption. The adsorption of Cr on soil increased the adsorption of As due to the additional As binding sites induced by Cr adsorption. These results suggest that As concentrations in the soil affected by CCA-treated wood could largely exceed predictions based on soil adsorption capacity for As. The evaluation of the impact on human health associated with CCA-treated wood should take consideration of the distinct transport characteristics of three elements and their interactions in soils

Entrepreneurial options for capacitive electrodialysis in the West Bank, Palestine

The research conducted within the Palestinian Dutch Academic Cooperation on Water (PADUCO) program confirms that capacitive electrodialysis (CED) has the potential of becoming the next innovation in water purification. It uses less energy (<0.5 kWh/m3 ) than reverse osmosis (3–10 kWh/m3 ) and is, in particular, promising for local small-scale use, since it produces clean irrigation or drinking water not continuously, but in batches. The current prototype produces 2 m3 /d for irrigation and 1.6 m3 for drinking water. Additionally, research has been conducted on options for entrepreneurship, taking into account a conducive context of required policies and institutions. These to an extent appear to be a condition for a successful introduction. The present publication aimed to research the feasibility of using this CED device for four types of use: irrigation for small farmers and large-scale farmers and small-scale and large-scale drinking water companies that pres-ently use reverse osmosis. Preliminary results showed that medium-sized water companies may most easily introduce the technology and that in the long-term small-scale water companies and small-scale farmers may benefit most from the new technology. A scenario for an improved entrepreneurial approach for drinking water companies and farmers is also developed considering their level of sophistication and the further development of the CED system towards large-scale production (of the CED system itself) and user-friendliness. At present, medium drinking water companies and medium farmers appear to be better positioned for the adoption of the new CED technology, as they produce and operate on a higher level of sophistication. Especially for the small farmers but also for small drinking water companies, more training and support, also with capital investment, is required. This can succeed if government agencies, Non-Governmental Organizations, investors, and other stakeholders align their efforts to that purpose, in this way creating a conducive policy and institutional environment. For the initial introduction of the CED system and in order to make it affordable, introduction for humanitarian purposes, refugees, Bedouins could be the first step.Delft Centre for Entrepreneurshi

Field-scale leaching of arsenic, chromium and copper from weathered treated wood

Earlier studies documented the loss of wood preservatives from new wood. The objective of this study was to evaluate losses from weathered treated wood under field conditions by collecting rainfall leachate from 5 different wood types, all with a surface area of 0.21 m 2. Wood samples included weathered chromate copper arsenate (CCA) treated wood at low (2.7 kg/m 3), medium (4.8 kg/m 3) and high (35.4 kg/m 3) retention levels, new alkaline copper quat (ACQ) treated wood (1.1 kg/m 3 as CuO) and new untreated wood. Arsenic was found to leach at a higher rate (100 mg in 1 year for low retention) than chromium and copper (<40 mg) in all CCA-treated wood samples. Copper leached at the highest rate from the ACQ sample (670 mg). Overall results suggest that metals' leaching is a continuous process driven by rainfall, and that the mechanism of release from the wood matrix changes as wood weathers. Metals leaching rates on a percent basis increase as treated wood weathers, although the mass released decreases

Health Risk Associated with Some Trace and Some Heavy Metals Content of Harvested Rainwater in Yatta Area, Palestine

Rainwater is considered a dependable source for domestic purposes within rural areas in Palestine. Harvested rainwater stored in cisterns is used to leverage deficits from municipal water supplies. Harvested rainwater in areas surrounded with industrial and agricultural activities is usually contaminated with heavy and trace metals. To study the effects of human exposure to heavy and trace metals, 74 harvested rainwater samples of rain-fed cisterns were collected from different localities in the Yatta area of Palestine in the months of January and February of 2016. The water samples were analysed for Ca, Mg, Al, Fe, K, Na, Ag, Li, Co, Ba, Bi, Sr, Ga, V, Rb, Mo, Beand Tl elements utilizing ICP-MS (inductively coupled plasma mass spectrometry). The selected trace metals were found within the concentration limits of the acceptable values, in accordance with WHO and Palestinian standards, except for K and Al, which were found above the allowed limits. The potential risks of the selected trace metals on the health of the local residents, as well as the possible sources of such heavy metals, were also studied. The Chronic daily intake (CDI) of each metal and health risk indexes (HRI) were calculated for both adults and children residents. The oral ingestion pathway was studied, including exposure via drinking water. The values for CDI were found in the descending order of: Ca &gt; Mg &gt; Na &gt; K &gt; Sr &gt; Fe &gt; Al &gt; Ba &gt; Li &gt; V &gt; Rb &gt; Ag &gt; Mo &gt; Ga &gt; Co &gt; Bi &gt; TI &gt; Be. The values of HRI were below 1 for most of the selected heavy metals, expect for Li for children, indicating potential health risk. The study also predicted that the local residents have a higher chance of developing cancer in their lifetime, especially children, with respect to the carcinogenic risk (CRing) values for Na, Mg, Al, Ba, K, Ca, Fe and Sr, which were greater than standardized limits (&gt;10&#8722;6). The rest of the selected elements were within the acceptable limit in the five different studied locations. Furthermore, univariate, multivariate and statistical analysis depending on one-way ANOVA, inter-metal correlation, cluster analysis (CA) and principal component analysis (PCA) results revealed that geogenic and anthropogenic activities were major sources of drinking water contamination by heavy metals in the Yatta area