The availability of long-term river discharge data covering at least 30 years is needed for proper hydrological studies, so the ability to predict river discharge is a matter of concern in the field of civil engineering. The Siak River in Pekanbaru City experiences overflowing water during the rainy season. One of the steps to prevent flooding on the Siak River is to utilize river discharge information, data-driven models utilize historical data to train or derive useful insights for predicting outputs, some data-driven models that are suitable for generating monthly historical data into new data include the Autoregressive Integrated Moving Average (ARIMA) method and the Thomas-Fiering method. The research begins by conducting the Rescaled Adjusted Partial Sums (RAPS) test to test the homogeneity of the data, then the prediction of discharge data with several schemes using the ARIMA and Thomas-Fiering methods, then the performance comparison between the two models is carried out using MAPE, RMSE, Nash-Sutcliffe, and correlation coefficient r. From the research results, it was found that the Thomas-Fiering method tends to be more accurate for predicting 1-year monthly discharge as well as long-term discharge, namely periods of 3, 5, and 7 years, with the best prediction being 1-year discharge prediction using 5 years of observed discharge with MAPE, RMSE, Nash-Sutcliffe, and correlation coefficient r values of 7.42%, 26.76 m3s-1, 0.92, and 0.96, respectively. This study could be a valuable reference for future studies in selection and further modification of data driven discharge simulation models.

Rubberwood sawdust, a lignocellulosic resource derived from industrial and agricultural waste, has the potential for conversion into biofuel. Rubberwood sawdust underwent pretreatment to enhance the accessibility of cellulose to enzymes. The pretreated rubberwood sawdust was subsequently mixed with potassium hydroxide (KOH) solution at 1% and 2% (w/v) concentrations. Each mixture was heated conventionally for 30 min, followed by microwave penetration for 5, 10, 15, 20, and 25 min that operated at 360 Hz, with a power level of 10% (input microwave power 150 Watts). Enzymatic hydrolysis was conducted on the pretreated samples with enhanced cellulose yields for 1 h at 50^oC. The result indicated that lignin content decreased from 29.83% (w/w) to 20.00% (w/w) and 17.36% (w/w) for 1% and 2% (w/v) KOH 25 min microwave penetration, respectively. The highest cellulose 43.73% (w/w), was obtained by 2% (w/v) KOH 25 min microwave duration. Samples were hydrolyzed for 1 h, 2% (w/v) KOH 25 min microwave exposure reached 0.027 g/L fermentable sugars. This method affected to lignin degradation, enhanced cellulose content to achieve higher sugar. The higher concentration of KOH resulted in significant lignin degradation. The microwave allowed for handling heat faster, saves energy and time, and creates less pretreatment waste.

Various manganese oxides have been reported to be an active catalyst for degradation of a dye. The synthetic manganese oxides can be conducted by several methods with the products having the different physicochemical properties and structures. This research focused on the synthesis of  hausmanite-type manganese oxide (Mn₂O₃)  by hydrothermal method with different mole  ratio  of  KMnO₄/glucose (3:1 and 2:3) and its application as a Fenton catalyst   for the degradation of methylene blue (MB). The as-synthesized manganese oxides were then characterized  by XRD for their structure and crystallinity and FTIR and Raman spectroscopy for the lattice vibrations. The average oxide state (AOS) of manganese in the as-synthesized manganese oxide was determined by the back titration method. The XRD results indicated  the presence of mixed phases with hausmanite  phase as major component and  cryptomelane and birnessite phases as minor ones. FTIR spectroscopy results showed the presence of O-Mn vibrations at wavelengths of 468 cm^-1, 487cm^-1, and 726 cm^-1. In addition, Raman spectroscopy results clearly showed the  specific vibrations of hausmanite at 655 cm^-1 and 653 cm^-1, respectively. The low value of  Mn AOS was obtained when the oxide was prepared in low ratio KMnO4/glucose and short reaction time. The as-synthesized hausmanite was  tested  as the Fenton catalyt for the degradation of MB.  The as-synthesized hausmanite synthesized with different mole rasio and reaction time showed similar catalytic activity for the degradation of MB with the highest MB degradation of 90.76%

The treatment of industrial wastewater is a source of environmental concern due to the presence of various pollutants that could have detrimental effects on ecosystems and human health. This research aims to investigate the potential of using corncob treated with 1M NaOH as an adsorbent for the removal of pollutants from wastewater collected from Sunseed Nigeria Limited. Corncob, a byproduct of the agricultural waste, has shown capability as an adsorbent due to its high surface area and availability at low cost. The research involved the preparation of corncob adsorbent and its characterization using technique; Fourier-transform infrared spectroscopy (FTIR). Adsorption experiment was conducted using continuous study by a fixed bed column with a 5.0 cm internal diameter and a height of 45cm, to evaluate the efficiency of corncob in removing pollutants from oil seed industrial effluent. The initial concentrations of the pH, TSS, DO, BOD, COD, Lead and Cadmium were examined to be; 4.8, 360 mg/l, 110 mg/l, 40 mg/l, 7000 mg/l, 1.268 mg/l and 0.138 mg/l, respectively. The best removal efficiency for cadmium and lead were: 65.94% and 94.01%, respectively at pH of 6.5 and contact time of 6hrs. Furthermore, the removal efficiency for TSS, BOD, and COD were: 20%, 55% and 57.14%, correspondingly. It was therefore concluded that corncob has proven to be a potential material for the treatment of physico-chemical pollutants from industrial effluent. It is recommended that the corncob should be utilized in large amounts for the treatment of industrial effluents.

This study compares the effects of peat water and normal water as mixing and curing water on the properties of crumb rubber and rice husk ash concrete (CR-RHA). The number of crumb rubber and rice husk ash used on the concrete followed the optimum mixture from a previous study, which was 5% and 10%, respectively. The crumb rubber was treated to overcome the lack of adhesion by soaking it in water for 24 hours. Normal concrete (PCC) was also cast as a control. CR-RHA and PCC concrete were mixed and cured using normal and peat water. Compressive strength, tensile strength, and porosity were tested at 3, 7, 14, 28, and 56 days. In general, CR-RHA concrete and PCC concrete showed lower performance when mixed and cured with peat water compared to normal water. Peat water with high acidity decreased the calcium content and developed the amount of pores in concrete, resulting in strength reduction. However, due to the excess pozzolan from rice husk ash, CR-RHA concrete had better resistance as the strength loss was relatively smaller, respectively 11.4% at 28 days and 10.6% at 56 days. Furthermore, CR-RHA concrete showed lower porosity, higher compressive strength, and tensile strength than PCC concrete due to rice husk ash that improved concrete density by generating CSH and crumb rubber that prevented concrete from spalling in an acidic environment. It was also found that compared to the previous study, pre-treated crumb rubber exhibited better mechanical and durability of concrete.