Revaluation of tidal waste in wastewater treatment plants

Resumen

Motivation: The latest European legislation on the use of chemical products in wastewater treatment requires a reduction in
their usage. Consequently, essential operations in this process, such as contaminant removal and sludge flocculation, require
alternative solutions [1]. Although replacing the efficiency and cost-effectiveness of chemical flocculants is challenging, natural
flocculants derived from plant residues and algae are proposed as a promising solution to reduce these polluting products while
also valorizing waste, thus promoting a circular economy [2].

Methods: This study focuses on two approaches: phosphorus removal from wastewater and improved sludge flocculation.

The optimal flocculant dose required for phosphorus reduction was determined using a jar test. Specifically, 500 mL of
wastewater was used for each sample, and soluble phosphorus levels were measured before and after the procedure. The
testing protocol for each chemical substitute was as follows [3]:

1. One minute of stirring at 80 rpm (revolutions per minute).

2. Fifteen minutes of stirring at 30 rpm.

3. Twenty minutes of settling.

For the sludge tests, the experiment was conducted manually using 100 mL of sludge.

Results and conclusions: The tests confirmed that natural flocculants effectively reduce contaminant levels. Similarly, they
were observed to aid in sludge flocculation and decrease the amount of chemical flocculant required. Additionally, while the
cationization of flocculants did not significantly affect sludge flocculation, it did enhance the removal of contaminants such as
phosphorus.

However, further research in this area is necessary, as these natural alternatives are still far from achieving the cost-effectiveness
and performance levels of traditional chemical flocculants.