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Calculating the number of baffle spaces that gives the target ED and CP is done with a non-iterative code (as opposed to the vertical code which is iterative sometimes). The optimal J/S value of 3 found from the CFD calculations can be used for horizontal flocculators since the flocculator can be made as wide as necessary (whereas in vertical flocculation, J was constrained by the height of the sedimentation tank), so iteration is not needed. The space between two baffles is determined using the following code:

{latex}
\large
$$
S = \mathop {\left( {{{\mathop Q\nolimits_{Plant} } \over {\mathop P\nolimits_{FlocChannel} }}} \right)}\nolimits^{{3 \over 4}} \mathop {\left( {{1 \over {\mathop {Pi}\nolimits_{JS} }}} \right)}\nolimits^{{1 \over 4}} \mathop {\left( {{{\mathop K\nolimits_P \mathop \alpha \nolimits_\varepsilon } \over {2ED}}} \right)}\nolimits^{{1 \over 4}}
$$
{latex}

The number of spaces per channel is determined by a non-iterative code also since the length of the channels are fixed to be the length of the sedimentation tank. Unlike in vertical flow flocculation, channels will always have an odd number of spaces to ensure that water flows into successive channels and eventually into the sedimentation tank. See Calculation of Flocculator Geometry for this equation.

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The number and spacing of floc spaces and floc baffles is calculated, as well as the Collision Potential, for the specific tank being drawn. The number of floc spaces is determined using the following function which forces the number of spaces to be an odd integer:

{latex}
\large
$$
{N_{FlocSpacesF}}(L,{\rm{T}},S) = Floor({{L + {\rm{T}}} \over {S + {\rm{T}}}} + 1,2) - 1
$$
{latex}

When calculating the spacing, L represents the length of the sed tank L.Sed and T represents the thickness of a baffle T.FlocBaffle. The minimum baffle spacing is 45 cm, which is the width that a human could walk through if needed for maintenance.

The center-to-center distance between baffles includes the spacing between baffles and the thickness of the baffles, for each channel. This is an array with an element for each channel. Since the horizontal design is untapered, each channel should have the same baffle spacing, but the code was kept as similar to the vertical code as possible. The exception is the last channel, which might have corrected spacing to make up for the wide entrance into the inlet channel.

{latex}
\large
$$
B_{FlocBaffle} = S_{FlocBaffle} + T_{FlocBaffle}
$$
{latex}

The total number of channels is found by dividing the total target collision potential by the collision potential per space and rounding that value up according to how many spaces are in a channel.

The residence time in the flocculator is determined as follows:

{latex}
\large
$$
Ti_{Floc} = {{HW_{FlocEnd} \cdot L_{FlocTank} \cdot
{{\rm P}_{FlocChannel}}} \over {Q_{Plant}}}
$$
{latex}

The height of water at the beginning of the flocculator is based on the height of water at the end of the flocculator plus the headloss through the flocculator. The head loss is determined per baffle (and per channel, and in the whole flocculator) based on the minor loss coefficient for flow around a baffle. An additional freeboard space was added to the water level (HW) found at the beginning of the flocculator to determine the height of the flocculator walls.

The head loss per baffle:

{latex}
\large
$$
HL_{FlocBaffle} = {{{Kp \cdot ({{J_{FlocChannel}} \over {S_{FlocBaffle}}}) \cdot Q_{Plant}^2 } \over {2 \cdot g \cdot (S_{FlocBaffle} \cdot P_{FlocChannel})^2 }}}
$$
{latex}

Water flows between channels in the flocculator. There are no ports as there were for the vertical flocculator because they were only necessary to maintain the vertical flow pattern. The width is the same as the baffle spacing in the previous channel and the height is the height of the floc tank.

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Length of "Lower" Baffle = Length of "Upper" Baffle:

{latex}
\large
$$
L_{FlocBaffleLower} = J_{FlocChannel} - S_{FlocBaffle}
$$
$$
L_{FlocBaffleUpper} = J_{FlocChannel} - S_{FlocBaffle}
$$
{latex}

The placement of the baffles in the flocculator is determined by algorithms that create a matrix of baffle displacements from the end of the flocculator (see this drawing program for step-by-step details of how the lamina, baffles, and other tank details are drawn). All baffles are also placed at the bottom of the tank, which is represented in a Z-matrix for the baffles.

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The time it takes to drain the flocculator can be approximated by:

{latex}
\large

$$
D = {\sqrt {{\sqrt {h_0 }} \over {{{\pi t} \over {8A_{res} }}\sqrt {{{2g} \over {K_{minor} }}} }}}
$$

{latex}

where D is the nominal valve diameter, h_o is the initial water height in the flocculator, A_res is the plan area the entire tank, and K_minor is the minor loss coefficient associated with the valve and subsequent expansion. Since there is a valve in every other channel, the maximum number of channels being drained by any given valve is two. Applying this equation to two channels gives the calculated value for the idealized size of the valve, which is then rounded up to the next available nominal diameter. For a flocculator that has only two channels, each of the channels will have a valve in it. In this case, the above equation will be applied to a single channel only.

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