Topic outline
Development of Protein-based Flocculant for Water Treatment of Wastewater Containing Suspended Substances × SDGs
Muddy soil that flows in from rivers coagulates as soon as it enters the ocean, depositing and damaging eelgrass beds, the cradle of young fish. Flocculants are used to purify the muddy water, but some of the conventional flocculants are harmful to living organisms. Therefore, we believe that we can contribute to the conservation and sustainable use of marine ecosystems (the SDGs 6 and 14) by developing flocculants made from natural materials that are safe for living organisms.
The United Nations has designated the decade starting in 2021 as the "Decade of Ocean Science," with the aim of contributing to the SDGs. Ocean science, as defined by the UN, includes the field of fisheries.
Summary
Study of the water treatment for wastewater containing suspended substances (SS). The reagents used in the wastewater treatment containing SS is called “flocculant”. Some flocculants now in use are harmful or not good for water environment. The purpose of our study is “development of safe and eco-friendly flocculants from biomaterials”.
Regulation for the wastewater containing in Japan
Kobe: 40 mg/kg
Yokohama: 70 mg/kg
Tokyo: 120 mg/kg
Nagoya: 200 mg/kg
Sapporo: 300 mg/kg
Flocculant → Reagent for the SS containing wastewater treatment
・Poly-aluminum chloride（PAC）
・Aluminum sulfate
・Poly-acryl amide
↓
・Aluminum: inhibition of plant root growth
・Acryl amide: carcinogenic
Purpose of our laboratory
・Development of eco-friendly & safe flocculant
↓
・Bio-degradable
↓
・Development of protein-based flocculant (Esterified protein)
Development of bio-flocculation
The following pictures show the “flocculation of diatomite by soy-protein based flocculant”.
Diatomite is common and ubiquitous soil or silt in Japan.
Right side cylindrical tube is a control experiment (in the absence of flocculant”.
I think you can see when flocculant is added, diatomite particles form large aggregates (called flocs) and settle.
This is “flocculation”.
On the other hand, the suspended substances that have densities near water are hard to settle even they form large flocs.
Next, I would like to show the pictures of “magnetic separation of water-bloom green alga”.
The flocculant used in this experiment is the same as the above experiment.
The densities of micro-organisms are very close to water and difficult to settle.
Then, aoko was flocculated with fine powder of Fe3O4 (magnetic particle) by soy-protein based flocculant, and removed by magnet.
