Journal of Applied Science and Engineering

Published by Tamkang University Press

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Performance of a coconut fiber-packed down-flow hanging filter for lower-strength swine wastewater treatment

 2026

 Volume 34

Nguyen Thien Tai1,2, Nguyen Thi Mai Phuong1,2, Phan Nhu Nguyet1,2, Nguyen Ai Le1,2, Nguyen Thi Ngoc Nhu1,2, and Ta Huynh Nhi1,2

1Faculty of Environment, University of Science (HCMUS), Ho Chi Minh City, 700000, Vietnam

2Vietnam National University, Ho Chi Minh City (VNU-HCM), Ho Chi Minh City, 700000, Vietnam

Received: February 24, 2026
Accepted: July 22, 2026
Publication Date: August 05, 2026

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Swine farming generates large volumes of wastewater requiring treatment before discharge. In small-scale Vietnamese farms, barn flushing dilutes biogas digester effluents, producing lower-strength wastewater that still exceeds discharge standards. This study evaluated a down-flow hanging filter (DHF) reactor packed with coconut fiber for the treatment of such lower-strength swine wastewater (chemical oxygen demand (COD): 741.90±25.98 mg/L; biochemical oxygen demand (BOD5): 127.93±4.01 mg/L; total nitrogen (TN): 44.67±2.92 mg N/L; total phosphorus (TP): 35.77±2.21 mg P/L). Two parallel reactors were operated: a coconut fiber packed reactor (DHF1) and an unpacked control (DHF0). During stable operation (days 15-44), DHF1 achieved removal efficiencies of 77.05±10.03% for COD, 79.30±7.06% for BOD5, 56.05±8.38% for TN, and 63.82±7.44% for TP, significantly higher than those of DHF0 (54.45±7.11%, 39.83±13.16%, 35.07±7.76%, and 35.53±8.53%, respectively). The improved treatment performance of DHF1 was associated with enhanced biomass retention within the coconut fiber matrix. First-order kinetic analysis further confirmed that coconut fiber packing enhanced apparent first-order rate constants (k) by 1.9-3.1-fold across all parameters compared to the unpacked control, providing concentration-independent evidence of enhanced reactor performance applicable to system design and scale-up. These results indicate that coconut fiber is a sustainable and biodegradable alternative for decentralized post-treatment of lower-strength swine wastewater from small-scale farms with diluted effluents.

Keywords: Down-flow hanging filter; Coconut fiber; Lower-strength wastewater; Small-scale farms; Organic matter removal; Nutrient removal

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