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It is well known that workability of high performance concrete (HPC) is dependent on slump value of concrete mixture. Moreover, slump retention is the most sensitive compared to a well-known slump value because it represents the durability of concrete mixture for its applications in the field of civil engineering. This research used the polycarboxylate ether (PCE) to increase slump value of concrete mixture and then verified the effect of PCE on the slump retention and compressive strength of different high-performance concretes. 0%, 0.5%, 1%, 2% of PCE were added into concrete mixture to yield a minimum compressive strength of f’c 50 MPa. The slump retention tests were performed at 0, 15, 30, 45, 60 and 75 minutes while the compressive strength tests were carried out at 3, 7, 14 and 28 days for every concrete sample. The result findings showed that the optimal concrete performance can be achieved by adding 2% of PCE to reach at a slump retention value of 45 minutes and a compressive strength of 53.84 MPa. Effect of PCE on the slump retention and compressive strength has been verified to contribute an insight into the application of a proper designed workability of HPC.

The current work aimed to investigate the removal mechanism of NH4+ from wastewater treatment plant effluent (WWTPE) onto the zeolite in the plug-flow column reactor (PFCR). The adsorption process was optimised as a function of length (2–15), time (0.5–202 min), and accumulation (0.05–2.4 mg/g) using response surface methodology (RSM). The optimal operating parameters for the adsorption were recorded after 134.89 min with 1.52 mg/L of zeolite with 6.685 cm of the column length where the predicted and actual removal was 99.79 vs. 98.00% of NH4+ from WWTPE. The bed depth service time (BDST), Thomas, and Yoon-Nelson models were used to explain the adsorption behaviour. In contrast, the mass transfer factor (MTF) model was carried out to determine the internal and external removal mechanism. The findings revealed that PFCR exhibited an efficiency for removing NH4+ from WWTPE. The dynamic adsorption behaviour was satisfactorily described by the BDST, Thomas, and Yoon-Nelson models. These findings confirmed that the empirical models had verified the suitable of PFCR for removing NH4+ from WWTPE. [ABSTRACT FROM AUTHOR]

Water quality degradation in the Selangor River will still be present in the years to come since pollutant loads from poultry farms, municipal wastewaters, and industrial wastewaters are not envisaged to be handled effectively. This will be facing the problems of water quality status to use for multiple purposes and to provide its aquatic environment continuously. The water quality evaluation system is used to assess the water quality condition in the river. This system distinguishes two categories of water condition i.e., the water quality index and water quality aptitude. The assessment of water quality for the Selangor River from nine stations along the main stream, which concludes that water has been highly polluted (index 5) immediately downstream of station 02 Selangor River before confluence with Kubu River due to high concentration of microorganisms and immediately downstream of station 06 Selangor River before confluence with Batang Kali River due to high concentrations of microorganisms and suspended particles, was verified. Mineral micropollutants were found to gradually pollute the stream water, ranging from the unpolluted water (index 1) in the upstream to the bad quality (index 4) in the downstream area. [ABSTRACT FROM AUTHOR]