[Paper Review] Estimating of optimal dose of PACL for turbidity removing from water

Anahita ghafoorisadatieh, Ebrhim Almatin+2 more|arXiv (Cornell University)|Apr 12, 2019

Coagulation and Flocculation StudiesEnvironmental Science20 references3 citations

TL;DR

This study investigates the optimal dosage of polyaluminum chloride (PACL) for efficient turbidity removal from water under varying pH levels and initial turbidity conditions. Using kaolin suspension (20–300 NTU), the research identifies pH 7 and a PACL dose of approximately 5 ppm as optimal, achieving maximum turbidity removal efficiency.

ABSTRACT

Removing suspended solids and colloids are one of the most important water treatment processes. In this research, experimental tests have been done to assess the effects of pH and different doses of PACL on turbidity removal efficiency. The optimum dose of poly aluminum chloride (PACL) for removing turbidity was also determined. Turbidity was created artificially by adding the Kaolin with six different initial turbidities between 20 to 300 NTU rested for half an hour. The results have been showed that the best removal efficiency was at the pH of natural water. The optimal doses consumption of PACL was about 5 PPM.

Motivation & Objective

• To evaluate the impact of pH and PACL dosage on turbidity removal efficiency in water treatment.
• To determine the optimal PACL dose for maximum turbidity reduction across varying initial turbidity levels (20–300 NTU).
• To identify the pH condition that maximizes PACL performance in removing suspended colloids and solids.
• To provide data-driven recommendations for practical application of PACL in water treatment systems.

Proposed method

• Artificial turbidity was created using kaolin clay at six initial turbidity levels ranging from 20 to 300 NTU.
• PACL was dosed at varying concentrations across different pH conditions, with pH adjusted to simulate natural water conditions.
• Turbidity was measured before and after PACL addition to assess removal efficiency.
• Experiments were conducted after a 30-minute rest period to allow for proper coagulation and settling.
• Statistical analysis of turbidity reduction was used to identify the optimal PACL dose and pH.
• The study focused on real-world applicability by testing conditions relevant to natural water sources.

Experimental results

Research questions

• RQ1 What is the effect of pH on PACL-induced turbidity removal efficiency?
• RQ2 How does varying PACL dosage influence turbidity removal across different initial turbidity levels?
• RQ3 At what PACL dose is maximum turbidity removal efficiency achieved?
• RQ4 Does the optimal PACL dose vary with initial turbidity levels between 20 and 300 NTU?
• RQ5 Is there a pH condition that maximizes PACL performance for turbidity removal?

Key findings

• The highest turbidity removal efficiency was achieved at pH 7, corresponding to the natural pH of water.
• An optimal PACL dose of approximately 5 ppm was identified as most effective for turbidity reduction.
• Turbidity removal efficiency improved significantly with increasing PACL dosage up to 5 ppm, after which gains diminished.
• The optimal PACL dose remained consistent across the tested turbidity range (20–300 NTU), indicating robustness.
• The results demonstrate that PACL is highly effective in removing colloidal and suspended particles when dosed at 5 ppm under neutral pH.
• The study confirms that pH control is critical for maximizing coagulation performance in PACL-based water treatment.