Ok efter et par forsøg og fejl og lidt hjælp fra @Rizier123, her er svaret:
html på formularsiden
For overskuelighedens skyld prøvede jeg at finde ud af, hvordan jeg tilføjer flere arrays af data til min db. Så på den dynamiske formularside har jeg input svarende til:
<p>Location: <input type='text' name='location[]' > </p>
Behandling af formularen og indtastning af data til DB
Først skiftede jeg fra mysqli til PDO, derefter kørte jeg med følgende kode:
try {
$sql = "INSERT INTO location_info (`department`, `participant`, `activity`, `location`, `rec_injuries`, `rec_injuries_timeframe`, `non_rec_injuries`, `non_rec_injuries_timeframe`, `competitor`, `cost_per_pair`, `usage_rate`, `leakage`, `cost_of_productivity`, `non_rec_impact`, `non_rec_sprain`, `non_rec_puncture`, `non_rec_dermatitis`, `non_rec_infection`, `non_rec_burns`, `non_rec_cuts`, `rec_impact`, `rec_sprain`, `rec_puncture`, `rec_dermatitis`, `rec_infection`, `rec_burns`, `rec_cuts`, `condition`, `general_id`)
VALUES (:department, :participant, :activity, :location, :rec_injuries, :rec_injuries_timeframe, :non_rec_injuries, :non_rec_injuries_timeframe, :competitor, :cost_per_pair, :usage_rate, :leakage, :cost_of_productivity,:non_rec_impact, :non_rec_sprain, :non_rec_puncture, :non_rec_dermatitis, :non_rec_infection, :non_rec_burns, :non_rec_cuts, :rec_impact, :rec_sprain, :rec_puncture, :rec_dermatitis, :rec_infection, :rec_burns, :rec_cuts, :condition, '{$id}')";
$stmt = $db->prepare($sql);
for($i = 0, $l = count($_POST["department_name"]); $i < $l; $i++) {
$loc_info = array(':department' => $_POST["department_name"][$i],
':participant' => $_POST["participant_name"][$i],
':activity' => $_POST["activity"][$i],
':location' => $_POST["location"][$i],
':rec_injuries' => $_POST["injuries"][$i],
':rec_injuries_timeframe' => $_POST["injury_time_frame"][$i],
':non_rec_injuries' => $_POST["non_rec_injuries"][$i],
':non_rec_injuries_timeframe' => $_POST["non_rec_injury_timeframe"][$i],
':competitor' => $_POST["competitor"][$i],
':cost_per_pair' => $_POST["cost_per_pair"][$i],
':usage_rate' => $_POST["usage_rate"][$i],
':leakage' => $_POST["leakage"][$i],
':cost_of_productivity' => $_POST["cost_of_productivity"][$i],
':non_rec_impact' => $_POST["non_rec_impact"][$i],
':non_rec_sprain' => $_POST["non_rec_sprain"][$i],
':non_rec_puncture' => $_POST["non_rec_puncture"][$i],
':non_rec_dermatitis' => $_POST["non_rec_dermatitis"][$i],
':non_rec_infection' => $_POST["non_rec_infection"][$i],
':non_rec_burns' => $_POST["non_rec_burns"][$i],
':non_rec_cuts' => $_POST["non_rec_cuts"][$i],
':rec_impact' => $_POST["impact"][$i],
':rec_sprain' => $_POST["sprain"][$i],
':rec_puncture' => $_POST["puncture"][$i],
':rec_dermatitis' => $_POST["dermatitis"][$i],
':rec_infection' => $_POST["infection"][$i],
':rec_burns' => $_POST["burns"][$i],
':rec_cuts' => $_POST["cuts"][$i],
':condition' => $_POST["condition"][$i] );
$stmt->execute($loc_info);
}