This study utilised a bio-sorbent from exhausted coffee husk (ECHBS) for the removal of ion Pb2+ from an aqueous solution. Four different activation methods were conducted by chemical activation with KOH, H3PO4, ZnCl2, and without chemical activation. In addition, the influence of process parameters such as heating temperature, heating time and heating gradient were investigated. Based on the experimental results, ECHBS without chemical activation (biochar) had the highest Pb2+ ion removal efficiency. The results showed that the heating temperature of 500°C, the heating time of 60 min and the heating rate of 15°C/min were optimum for preparation of the biochar. Under the optimum conditions, the removal efficiency and adsorption capacity reached 99% and 3.3 mg/g, respectively. The experimental data indicated that the adsorption isotherms are well fitted with the Langmuir Equilibrium isotherm model. Furthermore, the adsorption of the biochar follows the pseudo-second-order model. The result obtained from the present study confirmed that exhausted coffee husk is a suitable low-cost bio-sorbent for removing ion Pb2+.

Recent studies on agricultural waste as a potential precursor of biochar for heavy metals removal from aqueous solution had not considered exhausted coffee husk (ECH) as the potential one. It is well-known that the carbonization process influences the removal performance of biochar, particularly removal efficiency (RE). However, previous studies rarely considered the energy consumption during the carbonization process. The major objective of this study is to investigate the optimum carbonization parameter on ECH biochar for removal of ion Pb and Cu from economic stand point. The ECH biochar was produced at the different heating temperature (300 – 600°C) and heating time (30 – 120 minutes). In regard to specific cost of bio-sorption, the results showed that 500°C was the optimum heating temperature of ECH biochar for the Pb removal, while 600°C was the optimum one for the Cu removal. Furthermore, the heating time experimental outcomes suggested that the optimum heating time were 30 minutes for Pb removal and 120 minutes done Cu removal.  Key words: Biochar, carbonization temperature, carbonization time, exhausted coffee husk, specific energy cost

The present of nitrogen compounds in the form of ammonium (NH4 +) can contribute to serious pollution problems in surface water and groundwater. Among the most competitive ways, the physical removal method using low-cost biosorbent is considered an effective technique. However, compared to heavy metals and organic, less effort has been dedicated to exploring the potential ability of biochar as a biosorbent for ammonium removal. This study was focused on investigating the adsorption capacity of biochar from exhausted coffee husk (ECH) on ammonium in the aqueous solution. The biochar was produced at the different carbonization temperature (400 – 700 °C) and carbonization time (1-4h). The results showed that carbonization temperature of 700 °C during 1h of carbonization time was resulted in the highest adsorption capacity which was 1,13 mg/g of NH4 +. Several characterizations were conducted for observing surface morphological and pores area with scanning electron microscope (SEM) and Brunauer Emmert Teller (BET), respectively. The results showed that the pores were developed with the increasing temperature and resulted in higher absorbance.

Activated carbon (AC) from agricultural waste has become one promising way to produce AC regarding to low price of the precursor and its effect to environment. In this research, the solid waste from the basic biology practical in UPT. Basic and Central Laboratory, Andalas University (Unand) was utilized as the precursor for producing low price AC. The activation was done by chemical activation using three different activating agents which were zink chloride (ZnCl2), phosphoric acid (H3PO4), potassium hydroxide (KOH). The carbonization process was done at temperature of 700°C. The precursor and three different AC after activation were characterized using fourier-transform infrared spectroscopy (FT-IR) to examine  the functional group and scanning electron microscope (SEM) to observe the pores structure. The adsorption efficiency (AE) of each AC on methylene blue (MB) contained in laboratory wastewater was examined through adsorption process with retention time of 30 minutes at room temperature and neutral pH. SEM analysis showed that the three activating agents were resulting in higher surface area and more pores were formed. The highest AE of MB from laboratory wastewater for each AC were 97,5 %, 96,31%, and 90,79 for KOH, , ZnCl2, and H3PO4, respectively. Meanwhile, the highest adsorption capacity was achieved by AC through KOH activation with 0,003 mg/g

Indonesia is recently facing the fertilizer issue as the shortage supply of subsidized fertilizers is aligned with the increasing price of non-subsidized ones. So, it eventually resulted in the unstable price of agricultural commodities. The issue has been becoming an obstacle for farmers practising agricultural cultivation, particularly those in Batang Tajongkek Village, Pariaman, West Sumatra Province. It needs to develop its potential for natural resources to make organic fertilizer from cow manure. Furthermore, the solution supports the government program on establishing integrated agriculture. Two activities were conducted to empower the area's potentials, which were counselling and composting demos, respectively. The aim was to ensure knowledge transfer to the farmers regarding the technology and critical method of cow manure composting. During the counselling, the farmers were facilitated to discuss the related issue of sustainable integrated agriculture, organic farming, and the making process of compost. Meanwhile, the process of composting from cow manure was also shown during the demo. Furthermore, the farmer was facilitated to analyze the content of produced compost, which was mainly focused on the content of nitrogen (N), phosphorous (P), and potassium (K). The activities have empowered the people in the area to self-produce cow manure compost as an organic fertilizer. The analysis of the produced compost showed that the compost has yet to fulfil the national standard of solid fertilizer (SNI 7763:2018) regarding the content of macronutrients (N + P2O5 + K2O). However, the pH of produced compost has met the national standard. The pH was 7.27, which ranges from 4-9. For the compost to be utilized by the community, it is necessary to mix other materials in its manufacture so that the resulting compost complies with SNI.