Abstract.Excess phosphorus in water body will lead to eutrophication. This study investigated the phosphate removal efficiencies of unaerated and aerated filter systems using high composition of Calcium (Ca) steel slag as the filter media at different pH values of the wastewater influents. Lab-scale filters were developed using 25 mg/L synthetic wastewater and weekly sampling was done to monitor the phosphate removal efficiencies together with the concentration of metals (Calcium (Ca) and Magnesium (Mg). The results show that both unaerated and aerated systems have excellent phosphate removal efficiency at all acidic, neutral and alkaline pH feed, though unaerated systems removed slightly better compared to aerated systems; 76-98% and 69-97% respectively. The dominant phosphate removal mechanism for aerated systems was adsorption, meanwhilefor unaerated systems; both adsorption and precipitation for acidic and neutral pH, whileprecipitation was more dominant at basic pH. The performance of unaerated systems are slightly better compared to aerated systems, however, aerated systems are recommended to be applied when simultaneous removal of nutrients (phosphorus and nitrogen) are concerned.
Phosphorus in wastewater is one the main culprit which accelerates eutrophication in waterbody if it is not being treated properly. Steel slag filter emerged as one alternative treatment for wastewater. However, the variousness of metal oxides including Fe in steel slag will affect the phosphorus removal efficiency. Thus, this study was conducted to investigate the ability of a series of lab-scale high Fe electric arc furnace (EAF- slag) column filters in removing PO43- from synthetic wastewater. The systems were operated under aerated and unaerated within acidic and alkaline conditions. Synthetic wastewater contained 25 mg/L was prepared as the feed and monitored weekly basis for the PO43- removal efficiency and the total metals (Ca, Fe, and Mg) concentrations in the effluents. The results show that both aerated and unaerated high Fe EAF-slag filter systems have high PO43- removal efficiency under acidic condition, which unaerated system performed slightly better. It can be observed that unaerated systems performed better in removing PO43- at acidic and neutral pH values but not at extremely high pH. As for the PO43- removal mechanism was achieved by adsorption and precipitation at acidic pH and the concentration of Ca, Mg and Fe in effluents was related to the PO43- removal efficiency at different pH values.
Urbanisation had replaced the vegetation and soil cover, increasing heat retention by reducing the benefits of natural cooling mechanisms provided by evapotranspiration. The objective of this study is to investigate the potential of the alternative estimation performance for selected evapotranspiration (ET) methods for Batu Pahat station; for further prediction on the changes of future climatic parameters. Since the data is limited, ET0 estimation using temperature-based used are the Thornthwaite, Blaney-Criddle (original) and FAO Blaney-Criddle methods. Standard data formulation based on Batu Pahat latitude for meteorological parameters were used to estimate ET0 using basic radiation-based, the Penman (original) and Turc methods. Correlation results show that all three temperature-based methods estimated a similar range of ET0. For the radiation-based method, the Turc method seems slightly overestimated than the other four methods. However, these estimation needs to be explored further using the benchmark method, i.e., the FAO-56 Penman-Monteith, for the accuracy and reliabilities of these methods. Apart from temperature, it was found that ET0 did not correlate with rainfall and evaporation.
A green roof is an alternative roofing system of any building or house that provides a better environment for urban areas. It has the potential to mitigate urban water problems. This study aims to investigate the rainfall runoff performance of two non-monitored green roofs with two different slopes. The experiment uses two types of non-monitored green roofs, namely flat roofs and sloped roofs that were exposed to climatic conditions in Parit Raja. The physical characteristics of the roofs were observed and rainfall runoff data was collected. The results showed that when 4 L of water was manually poured onto the roofs, an average of 60.4% of water was retained on sloped roofs whereas 48.4% was retained on flat roofs. Based on the 5-minute interval data, the retention ranges between 55.6% and 71.2% for both roofs. In terms of daily rainfall for a week, the average percentage was 69.2% for sloped roofs and 70.6% for flat roofs. All three approaches show that the green roofs produced less water runoff compared to normal roofs with both slopes retained water efficiently. Therefore, rainfall runoff performance for two types of green roof slopes was investigated and the available storage for the green roofs was recorded. In conclusion, with little maintenance, non-monitored green roofs can be efficiently used as a water mitigation system for urban areas
Electric arc furnace (EAF) slag as filter media has been extensively used nowadays for wastewater treatment technology. Steel slag was produced as byproduct from steelmaking processes. However, different batches of steel slag production produce different composition. Thus, this study determined the chemical composition, pH value and points of zero charge (PZC) of two different samples of el ectric arc furnace (EAF) slag; high iron EAF slag (Slag HFe) and high calcium EAF slag (Slag HCa). The steel slag were characterized using Xray Fluorescence Spectroscopy (XRF) analysis for the chemical composition, extraction with boiling water for pH value, and salt addition method for PZC. Slag HFe was mainly consisted of 38.2% ferric oxide and 20.4% calcium oxide, 10.20 pH value and pH 10.55 for PZC. While for Slag HCa, they were composed of 1.64% ferric oxide and 49.5% calcium oxide of pH value of 11.11 and pH 11.75 for PZC. Therefore, Slag HCa was considered as a more basic species compared to Slag HFe.
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