Background/Objectives: This work is conducted to study the secondary treatment efficiency of dairy wastewater using Constructed Wetland (CW) with keratin (hair) waste modified substrate. Methods/Statistical Analysis: A pilot Horizontal Sub-Surface Flow (HSSF) constructed wetland was built using HDPE plastic crates. Lemongrass (Cymbsopoganflexuosus) was planted in the constructed wetland system as the primary vegetation. Modification of substrate was done using keratin (hair) waste. Two dairy industries were considered based on the products manufactured. Batch feeding process with Hydraulic Retention Times of 24 h, 48 h and 72 h was adopted. Findings: The following parameters were analysed and studied; Bio-chemical Oxygen Demand, Chemical Oxygen Demand, Total Kjeldahl Nitrogen, Total Phosphorus and pH. The effect of varying Hydraulic Retention Times and modification of substrate by keratin waste were also studied. Results showed good removal efficiency of the pollutants by the pilot-scale constructed wetland system. Based on the analysis of the experimental trials, it was observe that the growth of Cymbopoganflexuosus had a positive impact on the removal efficiency of the pollutants considered. The modification of substrate by keratin waste also increased the removal efficiency of the pollutants. Proper stabilization of the CW system will have positive impact on the removal of TP by keratin waste modified substrate layer as the major removal of phosphorus is done by uptake from plant roots and even though if soil acts as an adsorbent and phosphorus having the tendency to be trapped on adsorbents, as hair is a good adsorbent. High BOD/COD ratio was also observed for the treated effluent. Application/Improvements: Modification of substrate by hair is not recommended for short hydraulic retention times as the compaction of modified substrate layer tends to restrict the movement of water resulting in lower flow rate.
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