Pagination query not working - php

Question

I have a problem in my pagination. My scenario is I'll just the filters then click search. Then the result will show the output. But when I click on page 2 it returns to the query for all not the query that is filtered.
Controller
<?php //CONTROLLER
function maintenance(){
if($this->session->userdata('l#ginUs3r')) {
$session_data = $this -> session -> userdata('l#ginUs3r');
$data['u_id'] = $session_data['u_id'];
$data['u_uname'] = $session_data['u_uname'];
$data['u_pword'] = $session_data['u_pword'];
$data['u_role'] = $session_data['u_role'];
$data['is_active'] = $session_data['is_active'];
$config = array();
$config["base_url"] = base_url() . "personnel/maintenance/";
$config["total_rows"] = $this -> Main -> count_prf();
$config["per_page"] = 10;
$config["uri_segment"] = 3;
$this->pagination->initialize($config);
$page = ($this->uri->segment(3)) ? $this->uri->segment(3) : 0;
$data['prf'] = $this -> Main -> select_prf($config['per_page'], $page);
$data["prf_links"] = $this->pagination->create_links();
if(isset($_POST['search']))
{
if($_POST['division'] != "" && $_POST['group'] != "" && $_POST['department'] != "" && $_POST['position'] != "" )
{
if($_POST['date_rec'] != "" && $_POST['date_upto'] != "")
{
$where = "prf_div = '".$_POST['division']."' AND prf_group = '".$_POST['group']."' AND prf_status = '".$_POST['prf_status']."' AND prf_dept = '".$_POST['department']."' AND prf_position = '".$_POST['position']."' AND prf_status = '".$_POST['prf_status']."' AND prf_daterec BETWEEN '".$_POST['date_rec']."' AND '".$_POST['date_upto']."' ";
}
else
{
$where = "prf_div = '".$_POST['division']."' AND prf_group = '".$_POST['group']."' AND prf_status = '".$_POST['prf_status']."' AND prf_dept = '".$_POST['department']."' AND prf_position = '".$_POST['position']."' AND prf_status = '".$_POST['prf_status']."' ";
}
}
//NEXT IF FOR SEARCH
if($_POST['division'] == "" && $_POST['group'] == "" && $_POST['department'] == "" && $_POST['position'] == "" )
{
if($_POST['date_rec'] != "" && $_POST['date_upto'] != "")
{
$where = "prf_status = '".$_POST['prf_status']."' AND prf_daterec BETWEEN '".$_POST['date_rec']."' AND '".$_POST['date_upto']."' ";
}
else
{
$where = "prf_status = '".$_POST['prf_status']."' ";
}
}
$_SESSION['page_list'] = $where;
$config = array();
$config["base_url"] = base_url() . "personnel/maintenance/";
$config["total_rows"] = $this -> Main -> count_prf_where($_SESSION['page_list']);
$config["per_page"] = 10;
$config["uri_segment"] = 3;
$this->pagination->initialize($config);
$page = ($this->uri->segment(3)) ? $this->uri->segment(3) : 0;
$data["prf"] = $this -> Main -> fetch_prf($_SESSION['page_list'], $config["per_page"], $page);
$data["prf_links"] = $this->pagination->create_links();
}
$this -> load -> view('templates/header', $data);
$this -> load -> view('pages/maintenance', $data);
$this -> load -> view('templates/footer');
} else {
$this -> load -> view('templates/lheader');
$this -> load -> view('pages/login');
$this -> load -> view('templates/footer');
}
}
?>
View
<button type="button" class="btn btn-success btn-search-cust1 pull-right" onclick="window.location.href='<?=base_url()?>personnel/add_prf'"><span class="icon-file"></span></button>
<button type="button" name="back" class="btn btn-success btn-search-cust pull-right" onclick="window.location.href='<?=base_url()?>personnel/home'"> <span class="icon-home"></span> </button>
<?php $this -> load -> view('templates/maintenance-navbar'); ?>
<article class="grid_12 panel">
<div class=""><span class=""> </span><label class="listnames">Filter</label></div>
<div class="tab-field">
<form method="POST" action="<?=base_url()?>personnel/maintenance">
<label class="listnames">Division</label>
<select class="cust_fields" name="division">
<option value="">--Select--</option>
<?php if(!$ddl2){ ?>
<option value=""><?="NO DATA"?></option>
<?php } else { ?>
<?php foreach($ddl2 as $row){ ?>
<option value="<?=$row['d_id']?>"><?=$row['d_divname']?></option>
<?php } ?>
<?php } ?>
</select>
<label class="listnames">Group</label>
<select class="cust_fields" name="group">
<option value="">--Select--</option>
<?php if(!$ddl2){ ?>
<option value=""><?="NO DATA"?></option>
<?php } else { ?>
<?php foreach($ddl1 as $row){ ?>
<option value="<?=$row['g_id']?>"><?=$row['g_name']?></option>
<?php } ?>
<?php } ?>
</select>
<label class="listnames">PRF Status<!--FORMERLY ROLE --></label>
<select name="prf_status" id="roles" class="cust_fields">
<option value="Outstanding">Outstanding</option>
<option value ="Served">Served</option>
</select>
<br>
<label class="listnames">Department</label>
<select name="department" id="roles" class="cust_fields">
<option value="">--Select--</option>
<?php if(!$ddl3){ ?>
<option value=""><?="NO DATA"?></option>
<?php } else { ?>
<?php foreach($ddl3 as $row){ ?>
<option value="<?=$row['dept_id']?>"><?=$row['dept_name']?></option>
<?php } ?>
<?php } ?>
</select>
<label class="listnames">Position</label>
<select name="position" id="roles" class="cust_fields">
<option value="">--Select--</option>
<?php if(!$ddl5){ ?>
<option value=""><?="NO DATA"?></option>
<?php } else { ?>
<?php foreach($ddl5 as $row){ ?>
<option value="<?=$row['r_id']?>"><?=$row['r_rank']?></option>
<?php } ?>
<?php } ?>
</select>
<label class="listnames">Date Received</label>
<input type="date" name="date_rec" placeholder="mm/dd/yyyy" id="fromdate" autocomplete="off" style="height: 24px; width: 128px;">
<label class="listnames" style = "width: 15px;">To</label>
<input type="date" name="date_upto" placeholder="mm/dd/yyyy" id="fromdate" autocomplete="off" style="height: 24px; width: 128px;">
<button type="submit" name="search" class="btn btn-success cust_search"><span class="icon-search2"></span></button>
<!-- <input type="submit" name="search" value="Search"> -->
</form>
</div>
</article>
<table class="table">
<tr class="thead1" style = "background: #D6C9A4;">
<div class="row">
<div class="col-md-3">
<div class="row"><div class="col-md-3"><th >Division</th></div><div class="col-md-3"><th >Group</th></div><div class="col-md-3"><th >Department</th></div></div>
</div>
<div class="col-md-3">
<div class="row"><div class="col-md-3"><th >Position</th></div><div class="col-md-3"><th >Rank</th></div><div class="col-md-3"><th >Ex. No. of Personnel</th></div></div>
</div>
<div class="col-md-3">
<div class="row"><div class="col-md-3"><th >No. of Req. Personnel</th></div><div class="col-md-3"><th >No. of Served Personnel</th></div><div class="col-md-3"><th >Reason for PRF</th></div></div>
</div>
<div class="col-md-3">
<div class="row"><div class="col-md-3"><th >Date Received</th></div><div class="col-md-3"><th >Date Served</th></div><div class="col-md-3"><th >Age of PRF</th></div><div class="col-md-3"><th >PRF Status</th></div></div>
</div>
</div>
</tr>
<?php
if(!$prf)
{
?>
<h3 class="tab-field">No Data</h3>
<?php
}
$x = 1;
foreach($prf as $row){
$id = $row['prf_id'];
$now = time();
$your_date = strtotime($row['prf_daterec']);
$datediff = $now - $your_date;
$age = floor($datediff/(60*60*24));
$date_rec = substr($row['prf_daterec'], 0, -13);
$date_serv = substr($row['prf_dateserv'], 0, -13);
?>
<tr id="active" onclick="window.location.href='<?=base_url()?>personnel/prf_info/<?=$id?>'">
<td><?=strtoupper($row['d_divname'])?></td>
<td><?=strtoupper($row['g_name'])?></td>
<td><?=strtoupper($row['dept_name'])?></td>
<td><?=strtoupper($row['prf_position'])?></td>
<td><?=strtoupper($row['r_rank'])?></td>
<td><?=strtoupper($row['prf_ex_no_personnel'])?></td>
<td><?=strtoupper($row['prf_no_req_personnel'])?></td>
<td>Served Personnel</td>
<td><?=strtoupper($row['prf_reason'])?></td>
<td><?=$date_rec?></td>
<td><?=$date_serv?></td>
<td><?=$age?> Days</td>
<td><?=$row['prf_status']?></td>
</tr>
<?php } ?>
</table>
<div class="pagination-align"><?=$prf_links?></div>