\begin{pspicture}(0,0)(16,9)%\showgrid
\psset{arrowsize=4pt 3,arrowinset=0.15,framearc=0.05,linearc=0.1}

\rput(4,5){% select the origin here
\psset{unit=0.5cm}
\rput(0,0){\pscircle(0,0){0.3}
  \psline(0,0.2)(0,-0.2)
  \psline(0.2,0)(-0.2,0)
  \psline{->}(-2,0)(-0.4,0) % prior -> summing node

  \psline(0,4)(0,0.4)
  \rput(0,1.5){\psframe[fillstyle=solid,fillcolor=white](-0.25,-0.5)(0.25,0.5)
    \pspolygon*[linecolor=black,linearc=0,framearc=0](0,-0.2)(-0.2,0.2)(0.2,0.2)
    }
%  \psline[ArrowInside=->|,ArrowInsidePos=0.8,fillcolor=white,arrowinset=0,arrowsize=4pt 4,arrowlength=1]{-<}(0,4)(0,0.4)

  \psline{->}(0.4,0)(2,0) % summing node -> next

  \psline{->}(3,-6)(0,-6)(0,-0.4) % feedback -> summing node
}

\rput(-4,0){ % polymer production
  \psframe[shadow=true,shadowsize=1pt,shadowcolor=gray](-2,-2.5)(2,2.5)
  \rput(0,0){\parbox{1.85cm}{\centering\small
      Polymer production\\
  $\large\mathcal{P}$}}
}

\rput(4.25,0){ % manufacturing
  \psframe[shadow=true,shadowsize=1pt,shadowcolor=gray](-2.25,-2.5)(2.25,2.5)
  \rput(0,0){\parbox{1.85cm}{\centering\small
      Product manufacture\\
  $\large\mathcal{M}$}}

  \psline{->}(-1,-2.5)(-1,-5.3) % waste to reclamation
  \psline{->}(1,-2.5)(1,-3.7)(5.25,-3.7) % waste to disposal

}
\rput(8.5,0){
\pscircle(0,0){0.3}
  \psline(0,0.2)(0,-0.2)
  \psline(0.2,0)(-0.2,0)
  \psline{->}(-2,0)(-0.4,0) % prior -> summing node

  \psline(0,4)(0,0.4)
  \rput(0,1.5){\psframe[fillstyle=solid,fillcolor=white](-0.25,-0.5)(0.25,0.5)
    \pspolygon*[linecolor=black,linearc=0,framearc=0](0,-0.2)(-0.2,0.2)(0.2,0.2)
    }
%  \psline[ArrowInside=->|,ArrowInsidePos=0.8,fillcolor=white,arrowinset=0,arrowsize=4pt 4,arrowlength=1]{-<}(0,4)(0,0.4)

  \psline{->}(0.4,0)(2,0) % summing node -> next

%  \psline{->}(0,-3)(0,-0.4) % feedback -> summing node

}

\rput(11.75,0){% use
  \psframe[linestyle=dashed,dash=5pt
    4pt,linewidth=1.3pt,linecolor=darkgray]%
  (-1.25,-2.5)(1.25,2.5)
  \rput(0,0.5){\Large Use}
  % addition to stock
  \rput(0.2,-2){
    \psline{->}(0,1.5)(0,0.3)
    \rput(0,0){
    \psframebox{\tiny STOCK}
    }}
  }

\rput(10.5,5){% trade
  \psframe[linestyle=dashed,dash=6pt
    3pt,linewidth=0.8pt,linecolor=darkgray,framearc=0.25]%
  (-12.5,-1)(12.5,1)
  \rput(0,0){\Large International Trade}
}

\psline{->}(13,0)(15,0)

\rput(17.25,0){% use
  \psframe[shadow=true,shadowsize=1pt,shadowcolor=gray](-2.25,-2.5)(2.25,2.5)
  \rput(0,0){\parbox{1.85cm}{\centering\small
      Waste management\\
  $\large\mathcal{W}$}}

  \psline{->}(1,-2.5)(1,-4)(-1.75,-4) % waste mgt to disposal
}

\rput(21.5,0){
\pscircle(0,0){0.3}
  \psline(0,0.2)(0,-0.2)
  \psline(0.2,0)(-0.2,0)
  \psline{->}(-2,0)(-0.4,0) % prior -> summing node

  \psline(0,4)(0,0.4)
  \rput(0,1.5){\psframe[fillstyle=solid,fillcolor=white](-0.25,-0.5)(0.25,0.5)
    \pspolygon*[linecolor=black,linearc=0,framearc=0](0,-0.2)(-0.2,0.2)(0.2,0.2)
    }

%  \psline[ArrowInside=->|,ArrowInsidePos=0.8,fillcolor=white,arrowinset=0,arrowsize=4pt 4,arrowlength=1]{-<}(0,4)(0,0.4)

  \psline{->}(0.4,0)(1,0)(1,-7) % summing node -> downcycle
  \psline{->}(0,-0.4)(0,-6)(-11.5,-6) % summing node -> next

%  \psline{->}(0,-3)(0,-0.4) % feedback -> summing node

}

\rput[t](22.5,-7.1){\small To other use}

\rput(12.5,-4){
  \psframe[shadow=true,shadowsize=1pt,shadowcolor=gray,fillcolor=lightgray,fillstyle=solid](-3,-0.7)(3,0.7)
  \rput(0,0){Disposal $\large\mathcal{D}$}
}

\rput(6,-6){
  \psframe[shadow=true,shadowsize=1pt,shadowcolor=gray](-4,-0.7)(4,0.7)
  \rput(0,0){Reclamation   $\large\mathcal{R}$}

  \psline{->}(0.5,0.7)(0.5,1.7)(3.5,1.7) % reclamation yield loss
}



}
\rput[tl](0,0.5){\small
  \rput[l](0,0.9){\psline{->}(0,1ex)(1,1ex)\hspace{1.2cm} One-directional flow}
  \rput[l](0,0.4){
    \rput{90}(0.5,1ex){\psset{unit=0.5cm}
      \psline(0,-1)(0,1)
      \psframe[fillstyle=solid,fillcolor=white](-0.25,-0.5)(0.25,0.5) 
      \pspolygon*[linecolor=black,linearc=0,framearc=0](0,-0.2)(-0.2,0.2)(0.2,0.2)
    }\hspace{1.2cm} Bi-directional flow (arrow indicates positive sense)}
  \rput[l](0,-0.1){
    \rput(0.5,1ex){\psset{unit=0.5cm}
    \pscircle(0,0){0.3}
    \psline(0,0.2)(0,-0.2)
    \psline(0.2,0)(-0.2,0)}
    \hspace{1.2cm} Material Balance Node}
}
  

\end{pspicture}