Jatinangor — A 15-gram alum dosage has been identified as the most effective level for reducing Total Dissolved Solids (TDS) and improving the clarity of shrimp aquaculture wastewater. The finding comes from a study by Lady Ayu Sri Wijayanti, Mochhamad Ikhsan Cahya Utama, Galih Hamdani, and Andini Nur Afifah from Universitas Padjadjaran, published in 2026 in the East Asian Journal of Multidisciplinary Research (EAJMR). The study is significant as shrimp farming remains one of the largest contributors to organic wastewater pollution in coastal environments.
The rapid expansion of intensive shrimp farming has supported global protein supply and economic growth, but it has also created environmental challenges. Shrimp pond wastewater is often filled with uneaten feed, shrimp waste, and dissolved organic matter, resulting in high TDS levels and turbidity.
If discharged untreated, this wastewater can trigger eutrophication, reduce dissolved oxygen, and disrupt marine ecosystems. Effective treatment systems are therefore increasingly urgent.
The researchers tested alum performance using a modified jar test method, a laboratory simulation commonly used to evaluate coagulation and flocculation efficiency. Four dosage levels were tested: 0 grams, 5 grams, 10 grams, and 15 grams per 500 mL of wastewater sample.
The results showed an unusual pattern.
Without alum, wastewater remained highly turbid with an average TDS of 1312 ppm. At 5 grams and 10 grams, TDS levels unexpectedly increased to 1372 ppm and 1421 ppm. According to the researchers, this happened because the alum ions had not yet reached the threshold needed to form stable flocs, leaving dissolved ions in the water.
The major breakthrough occurred at 15 grams.
At this dosage, water clarity visibly improved while TDS dropped sharply to 1320 ppm from an initial level of around 2000 mg/L. This marked the activation of the sweep coagulation mechanism, where pollutants become trapped in larger flocs and settle at the bottom.
The researchers explain that this process is crucial because larger flocs settle faster, making the water cleaner and reducing pollution loads more effectively.
However, the study also found a side effect.
Higher alum doses significantly lowered water pH, making the treated water more acidic. This happened because alum hydrolysis released hydrogen ions into the water, consuming alkalinity.
This means that while alum is effective for TDS and turbidity reduction, an additional neutralization process is needed before releasing the treated water into the environment. The researchers recommend lime or similar alkaline materials for pH adjustment.
For shrimp farmers, the study offers practical guidance in designing wastewater treatment systems. With the right dosage, pollution loads can be reduced more efficiently without unnecessary chemical waste.
From an environmental perspective, applying this method could help reduce coastal pollution and support sustainable aquaculture growth.
As shrimp production continues to rise, this research highlights how simple chemical treatment strategies can help balance industrial productivity with environmental protection.
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