High amount of orthophosphate will accelerate the growth of autotrophs and eutrophication will occur. This phenomenon decreases the water quality and as a result may increase the cost of water treatment for drinking water. The overabundance of orthophosphate occurs when untreated or inadequately-treated wastewater from domestic and industrial activities is released into water bodies. Conventional treatment has been developed to treat wastewater. However, it is not effective for phosphorus removal, hence, high-cost advanced treatment is needed to remove phosphorus. Thus, alternative low-cost treatments for phosphorus removal are needed. Therefore, this study was conducted to understand and investigate the mechanisms of phosphorus removal using two different setups of steel slag filter, Set 1 for high Fe and Set 2 for high Ca. The study was operated at different pH values of 3, 5, 7, 9 and 11 under aerated and unaerated conditions. The samples of steel slag from 12 filters that has been run for three months for each set were semi-quantitatively analysed using scanning electron microscope-energy dispersive X-ray (SEM-EDX) to identify the adsorption of phosphate ion on the surface of the steel slag. The results of SEM-EDX studies showed that adsorption mechanism of phosphate removal takes place on the surface of the steel slag. The precipitates in the steel slag filters were collected and analysed for X-ray diffraction (XRD) for chemical compound identification and the precipitates were confirmed to be Fe 3 O 4 , a precursor of iron phosphate related compound.

Excessive amount of phosphorus in wastewater prior discharged are one of the major cause of eutrophication in lakes and rivers making phosphorus removals are essentials. However, removing phosphorus from wastewaters required a high cost treatment system to be installed at treatment facilities. To provide alternative solutions, this study was conducted to investigate the effectiveness of L-shape semi aerated filter with steel slag as filter media to provide a cost effective treatment system using natural media as a solution to remove phosphorus from domestic wastewater. The L-shaped semi aerated filter was constructed and installed onsite at Sewage Treatment Plant (STP) UTHM. Then, the laboratory test was conducted twice a week to analyse five parameters including pH, turbidity, dissolved oxygen (DO), chemical oxygen demand (COD), and total phosphorus (TP). The results showed that the effluent from the L-shape steel slag filter was alkaline with a pH value range of 7.22 to 9.71 due to alkaline properties of steel slag. Turbidity value of effluent at vertical section was higher than horizontal section as it may affect the COD removal of the filter. In the vertical system, the DO value range was higher (1.5 to 6.9 mg/L) than the horizontal system (1.27 to 5.5 mg/L) since oxygen was introduced by aeration process. Furthermore, this system showed good COD removal efficiencies with values ranged from 10% to 76%. Lastly, total phosphorus removal efficiencies also showed great removals with range of 29% to 68%. From the results obtained, steel slag with high-Ca content showed excellent potential in removing phosphorus from domestic wastewater.

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Phosphorus is the element that promotes growth in plant. However, over loading of phosphorus into surfaces water leads to severe environmental problems known as eutrophication. Improper treatments of phosphorus removal prior discharges from industrial effluent are one of the contributions to eutrophication. Textile effluent is one of the sources of phosphorus loading in surface water with concentration of 1-9 mg/L P. Since attentions are given in removing the color from the effluent, phosphorus is commonly ignored in wastewater treatment system. Thus, the study of phosphorus removal in textile wastewater is conducted using steel slag system filter under aerated (ASSF) and unaerated (USSF) condition. The systemwas set up for influent pHrange of 5.30-7.00 at primary treated wastewaterfor textile wastewaterunder aerated and unaerated condition. Sampling was done twice a week for 12 weeksand analyzed for Total phosphorus concentration. The Activated Carbon(ACF)filterin the existing treatment system is also sampled to compare the removal efficiency The USSFfilter shows better removal than ASSFfilter with46% to 70%of efficiency removal.Meanwhile, the removal efficiency of ASSF is 37% to 66%.The adsorbate formed in ASSF is analyzed using SEM-EDX and the precipitation formed in USSF is analyzed using XRD.This shows that steel slag filter provides promising result in phosphorus removal.

Eutrophication is one of the global concerned due to algae bloom in the natural surface water such as lakes and swamp area. Industrial effluent with incomplete treatment discharged has become one of the main culprits to this phenomenon. Approximately, 0.3 – 13 mg/L of total phosphorus can be found in the final discharge of industrial effluent showing that the existing treatment including an activated carbon filter (ACF) has limitation in polishing the phosphorus. Therefore, this 16 week of study has been designed to study the alternative treatment phosphorus removal at secondary stage to replace the tertiary treatment by using steel manufacturing by-product as filter media for effective phosphorus removal from the textile industry wastewater. Two units of lab-scale vertical steel slag filter (SSF) systems under aerated and unaerated conditions have been developed for this study. The samples were collected and analysed biweekly for selected parameters including pH, alkalinity, DO and TP. The results obtained from this study show that the unaerated steel slag filter has a high efficiency of TP removal which ranged from 46% to 70% compared to the aerated SSF with removal efficiency ranged from 37% to 66%. Besides, the existing ACF removal efficiency was ranged from 36% to 54%. Thus, the use of steel slag in removing phosphorus from textile wastewater is possible with the used of both aerated and unaerated steel slag filter systems. Furthermore, the removal mechanism involved was likely to be precipitation and adsorption.