<p>Highly polluted urban storm water from e.g. highways can contain large amounts of heavy metals that may cause harm if they are discharged into recipients. To remove the heavy metals a possible low-cost method that does not require much maintenance, could be the use of reactive filters with filter materials consisting of industrial residues or other cheap mineral based materials. Dissolved metal ions are removed by reactive filters through the processes of ions binding to active sites on the surface of the filter materials, or by formation of insoluble precipitates.</p><p>The ability of CaO-treated granulated blast-furnace slag, iron oxide coated sand, olivine and nepheline to remove seven heavy metals (Cr, Cd, Cu, Ni, Zn, Pb and Hg) from urban storm water was studied. Initially batch experiments were performed where the effect of pH, dissolved organic carbon (DOC) and dissolved ions on the adsorption efficiency was studied. The experiments were conducted with urban storm water and with a reference solution (10 mM NaNO3), both containing the same concentration of heavy metals (approx. 1 μM). The two materials with the best results were further investigated in a column study, where the capacity of the filter was tested. Chemical equilibrium calculations using the program Visual MINTEQ were performed in order to assess the role of precipitation as a mechanism for removal.</p><p>The results show that the blast-furnace slag was the most effective filter material and that it has great potential to be used as a heavy metal remover. Also the iron oxide coated sand worked satisfactory. The highest degree of removal was obtained for lead, cadmium and nickel, for which the removal efficiency exceeded 90% after a load of 300 times the water volume in the columns. For some metals, mainly copper, chromium and mercury the dissolved organic matter affected the removal negatively. The chemical mechanisms causing the removal are specific adsorption to the surfaces of the materials, and for the blast-furnace slag probably precipitation of insoluble metal sulfides.</p> / <p>Starkt förorenat dagvatten som rinner av från exempelvis motorvägar, kan innehålla betydliga mängder tungmetaller som kan orsaka skada om de kommer ut i omgivande vattendrag. En billig metod för tungmetallavskiljning, som inte kräver så mycket underhåll, skulle kunna vara att använda reaktiva filtermaterial bestående av restprodukter eller andra mineraliska lågkostnadsmaterial. Reaktiva filter fungerar som metallavskiljare genom att de lösta metalljonerna binder till ytgrupper på filtermaterialen eller att svårlösliga utfällningar bildas.</p><p>Förmågan att avskilja sju tungmetaller (Cr, Cd, Cu, Ni, Zn, Pb och Hg) ur dagvatten har undersökts för fyra mineraliska filtermaterial, kalciumoxiddopad masugnsslagg, järnoxidsand, olivin och nefelin. Studien inleddes med skakförsök där adsorptionens pH-beroende undersöktes. Försöken gjordes dels med dagvatten, dels med en referenslösning (10 mM NaNO3) med samma tungmetallkoncentration (ca 1μM). Detta gjordes för att studera effekter av löst organiskt material och andra ligander på adsorptionen. Därefter testades de material som uppvisat bäst resultat i skakförsöket i kolonnförsök, ett försök som mer efterliknar en praktisk tillämpning och där filtrets kapacitet kan studeras. Genom kemiska jämviktsberäkningar med programmet Visual MINTEQ var det möjligt att undersöka om bildningen av svårlösliga metallutfällningar bidrog till metallavskiljningen.</p><p>Resultaten visar att slaggen var det effektivaste filtermaterialet och att detta har stor potential att användas för avskiljning av tungmetaller. Även järnoxidsanden fungerade tillfredsställande. De metaller som avskiljdes bäst var bly, kadmium och nickel, för vilka avskiljningen var > 90 % i kolonnförsöket efter en belastning motsvarande 300 gånger vattenmängden i kolonnerna. För vissa metaller, främst koppar, krom och kvicksilver, försämrades avskiljningen betydligt när löst organiskt material fanns närvarande. Mekanismerna som står för avskiljningen är till störst del adsorption till grupper på filtermaterialens ytor, men bildning av svårlösliga metallsulfider är också tänkbar för slaggen.</p>

Highly polluted urban storm water from e.g. highways can contain large amounts of heavy metals that may cause harm if they are discharged into recipients. To remove the heavy metals a possible low-cost method that does not require much maintenance, could be the use of reactive filters with filter materials consisting of industrial residues or other cheap mineral based materials. Dissolved metal ions are removed by reactive filters through the processes of ions binding to active sites on the surface of the filter materials, or by formation of insoluble precipitates. The ability of CaO-treated granulated blast-furnace slag, iron oxide coated sand, olivine and nepheline to remove seven heavy metals (Cr, Cd, Cu, Ni, Zn, Pb and Hg) from urban storm water was studied. Initially batch experiments were performed where the effect of pH, dissolved organic carbon (DOC) and dissolved ions on the adsorption efficiency was studied. The experiments were conducted with urban storm water and with a reference solution (10 mM NaNO3), both containing the same concentration of heavy metals (approx. 1 μM). The two materials with the best results were further investigated in a column study, where the capacity of the filter was tested. Chemical equilibrium calculations using the program Visual MINTEQ were performed in order to assess the role of precipitation as a mechanism for removal. The results show that the blast-furnace slag was the most effective filter material and that it has great potential to be used as a heavy metal remover. Also the iron oxide coated sand worked satisfactory. The highest degree of removal was obtained for lead, cadmium and nickel, for which the removal efficiency exceeded 90% after a load of 300 times the water volume in the columns. For some metals, mainly copper, chromium and mercury the dissolved organic matter affected the removal negatively. The chemical mechanisms causing the removal are specific adsorption to the surfaces of the materials, and for the blast-furnace slag probably precipitation of insoluble metal sulfides. / Starkt förorenat dagvatten som rinner av från exempelvis motorvägar, kan innehålla betydliga mängder tungmetaller som kan orsaka skada om de kommer ut i omgivande vattendrag. En billig metod för tungmetallavskiljning, som inte kräver så mycket underhåll, skulle kunna vara att använda reaktiva filtermaterial bestående av restprodukter eller andra mineraliska lågkostnadsmaterial. Reaktiva filter fungerar som metallavskiljare genom att de lösta metalljonerna binder till ytgrupper på filtermaterialen eller att svårlösliga utfällningar bildas. Förmågan att avskilja sju tungmetaller (Cr, Cd, Cu, Ni, Zn, Pb och Hg) ur dagvatten har undersökts för fyra mineraliska filtermaterial, kalciumoxiddopad masugnsslagg, järnoxidsand, olivin och nefelin. Studien inleddes med skakförsök där adsorptionens pH-beroende undersöktes. Försöken gjordes dels med dagvatten, dels med en referenslösning (10 mM NaNO3) med samma tungmetallkoncentration (ca 1μM). Detta gjordes för att studera effekter av löst organiskt material och andra ligander på adsorptionen. Därefter testades de material som uppvisat bäst resultat i skakförsöket i kolonnförsök, ett försök som mer efterliknar en praktisk tillämpning och där filtrets kapacitet kan studeras. Genom kemiska jämviktsberäkningar med programmet Visual MINTEQ var det möjligt att undersöka om bildningen av svårlösliga metallutfällningar bidrog till metallavskiljningen. Resultaten visar att slaggen var det effektivaste filtermaterialet och att detta har stor potential att användas för avskiljning av tungmetaller. Även järnoxidsanden fungerade tillfredsställande. De metaller som avskiljdes bäst var bly, kadmium och nickel, för vilka avskiljningen var &gt; 90 % i kolonnförsöket efter en belastning motsvarande 300 gånger vattenmängden i kolonnerna. För vissa metaller, främst koppar, krom och kvicksilver, försämrades avskiljningen betydligt när löst organiskt material fanns närvarande. Mekanismerna som står för avskiljningen är till störst del adsorption till grupper på filtermaterialens ytor, men bildning av svårlösliga metallsulfider är också tänkbar för slaggen.

This study was influenced by the circumstances of children in need of care and protection. I conducted the study through a lens that takes the perspectives of “family life” seriously. Section 28(1)(b) of South Africa’s Constitution provides for the right to family care, parental care, or appropriate alternative care to a child who is removed from family life. This provision prioritises the nurturing and development of children in families. South Africa has a diversity of family models which provide family or parental care to children. Children also face various challenges and difficulties in the family environment, such as abuse, neglect, poverty, exploitation, and other traumatic experiences which make them more vulnerable and in need of care and protection. These circumstances are identified as grounds for mandatory intervention and often influence the decision by the children’s court to remove children. The study demonstrates how family care, parental care, or appropriate alternative care are provided in South Africa’s Children’s Act, enforced by the judiciary, and have evolved in practice. Unfortunately, the Children’s Act does not explicitly provide for families, family care and the responsibility of the state to assist families to enable them to function optimally. Government and stakeholders therefore lack guidance in their engagement with the family to address the plight of children in families or raise the quality of life of the family on a continuous basis. The social worker who conducts investigations into the circumstances of the child who is in need of care and protection, must facilitate the provision of prevention and early intervention services with a view to strengthening the family. Unfortunately, social workers sometimes abuse their powers by removing children without prioritising the support needed to keep them in families. Furthermore, the state’s assistance in supporting families may be challenging due to resource constraints, underspending on the state budget, and delay in the delivery of services. Before the children’s court decides to remove the child into alternative care it must, upon identifying a specific ground for mandatory alternative care intervention, conduct an investigation and hold an inquiry regarding the circumstances of the child. The parent and the child must have access to information and participate in the decision-making process. Once the decision to remove the child is reached, the children’s court can opt for different alternative care options. It is crucial to decide on alternative care of a nature and quality that resembles family life. Such care must enable the child and the parent to mutually enjoy each other’s company, as this is an essential element of family life. Thus, the state must put measures in place to ensure that the child establishes contact and has a continuous relationship with family members in view of possible reunification with the family. Alternative care must also provide permanency planning which must explore the option of reuniting the child with his or her family after removal, or adoption if reunification efforts fail. Although adoption is preferred upon failure of reunification efforts, it is challenged by policy and practice which, if not carefully considered, may impact on the right of the child to family life. South Africa has ratified the United Nations Convention on the Rights of the Child (CRC) and is bound to develop its policies in line with the CRC. It is an issue of concern as to whether the implementation of the Children’s Act goes far enough in meeting CRC standards or complying with the Constitution. Thus, the study is means of comparative research, which includes international standards and foreign jurisdictions, with the view of suggesting improvements for South African child legislation. Recommendations for the best possible options towards refining the Children’s Act are made. The proposed provisions could advance the reform of child and family services and thus make a difference in the lives of children in families. / Thesis (LLD)--University of Pretoria, 2012. / gm2013 / Private Law / unrestricted

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