The purpose of this research was to process a mixture of paper waste and garden waste based on material flow analysis and to analyze its parameters based on water content, ash content, heating value, along with Thermogravimetry Analysis (TGA)/Derivative Thermogravimetry (DTG). The garden waste treatment process consists of shredding, drying with a rotary dryer, separator, and then shaving with a hammer mill. Paper waste only needs a shredder process. Then, the mixing process and pelletizing of paper waste as well as garden waste are carried out according to the variation (w/w) 100% paper (K100), 75% paper (K75), 50% paper (K50), 25% paper (K25), and 100% garden waste (K0). The water content ranged from 5.8 to 15.25%. From K0 to K100 samples, the ash content increased from 4.54 to 9.85%. A correlation of 0.9047 was found from samples K0 to K100. There was a correlation between increasing calorific value along with the mixture with paper waste. The caloric value in K0 to K100 increased from 13.11 to 19.03 MJ/kg. The TGA/DTG analysis reduced mass due to water evaporation, devolatilization, and carbonization processes.

The generation of polyethylene terephthalate (PET) plastic and garden waste must be recycled to support the circular economy. An alternative way to reduce the plastics waste is to reduce this waste by converting it into energy such as Refused Derived Fuel (RDF) as an alternative for processing waste. Substitution of plastic and garden waste is an opportunity to be analyzed. Hence, This study aimed to investigate the potential for converting material substitution from PET and garden waste into RDF. The RDF characterized test method was carried out by proximate, water content, ash content, and analysis. At the same time, the calorific value. was tested by bomb calorimetry. Substitution of the mixture of plastic and garden waste affects each parameter of RDF pellet quality including water, ash, and caloric value (sig.< 0.05). The increase of plastic waste in pellets consistently increases the calorific value of RDF from 18.94 until 25.04 MJ/kg. The RDF pellet water and ash content also invariably affect the rate of increase in the calorific value of RDF in the multilinearity model (sig.<0.05; R2 is 0.935). The thermal stability of the pellets occurred at a temperature of 5000C decomposition of hemicellulose, cellulose, and lignin in mixed garden waste with plastic in RDF pellets. The decrease in the decomposition of PET into terephthalic acid monomer from the thermal stability of raw materials and waste PET plastic pellets occurs at a temperature of 4500˚C. This potential finding can be used as a basis for consideration in regions or countries that have the generation of garden waste and plastic, especially the type of PET to be used as an environmentally friendly fuel.

The generation of municipal solid waste (MSW) in Bali has various environmental impacts. One of the updates on sustainable waste processing is the RDF treatment plant processing. Before carrying out the processing, MSW characterization is needed because each region has a diverse composition. The processing of MSW into RDF provides benefits for achieving MSW reduction targets, renewable energy use, and the reduction of greenhouse gas (GHG) emissions. For this reason, this study was conducted to determine the potential of MSW in Bali as an alternative to renewable fuel and its potential to reduce GHG. MSW's potential calorific value as a raw material for RDF in Bali can reach 9.58 - 17.71 MJ/kg. The implementation of processing waste into RDF in pellets has shown a calorific value of ± 3904 - 4945 kkcal/kg. Implementing MSW processing into RDF in Bali can reduce GHG by 178 - 330 times compared to open dumping.

The Sludge Treatment Plant (STP) in Surabaya produces solid waste in the form of sludge. The STP in Surabaya provides for Solid Separation Chamber (SSC), equalization unit, Oxidation Ditch (OD), final clarifier, distribution unit, polishing pond, sludge Drying Area (DA), Sludge Drying Bed (SDB), and reservoirs. Sludge waste generation is usually collected in DA and SDB units. This sludge is usually reprocessed for the recycling process, one of which is the waste to energy conversion with a thermochemical process. The difference between these two units is that DA is the sludge from preliminary treatment, while SDB is the sludge from secondary treatment, usually producing microbial biomass. This study aimed to evaluate the sludge produced by the two processing units as solid fuel. The water content of the DA sample is lower because the DA unit has mechanical processing, which separates solids from water. The results of the proximate test resulted in a significant difference between the SDB and DA units. The caloric value, water, ash, and fixed carbon values are significant (<0.05), while the volatile values differ for DA and SBD units. This shows that different treatment is needed for each unit to be appropriately processed as fuel.

Dalam studi ini dipelajari kemampuan adsorpsi tanah liat lokal alami untuk menyisihkan warna pada larutan mengandung zat warna tekstil Reactive Red 141 (RR 141). Tanah liat lokal alami yang diteliti sebagai alternatif adsorben yang murah dalam studi ini berasal dari daerah Arcamanik, Citatah dan Dago (Bandung, Indonesia). Aspek yang dipelajari meliputi pengaruh dosis adsorben, waktu kontak dan konsentrasi awal larutan zat warna. Mekanisme proses adsorpsi dievaluasi menggunakan model isoterm, kinetika dan parameter termodinamika. Hasil penelitian ini menunjukkan bahwa peningkatan efisiensi penyisihan warna dan penurunan kapasitas adsorpsi tanah liat terjadi pada dosis adsorben lebih tinggi dan konsentrasi awal zat warna lebih rendah. Dosis adsorben optimum untuk tanah liat Arcamanik, Dago dan Citatah dicapai pada dosis masing-masing sebesar 10 g/L; 10 g/L; dan 8 g/L, dengan penyisihan zat warna berturut-turut sebesar 65,9%; 65,9%; dan 76,6%. Waktu kesetimbangan adsorpsi RR 141 pada tanah liat Arcamanik dan Citatah dicapai pada 60 menit sedangkan pada tanah liat Dago tercapai pada 120 menit. Kinetika adsorpsi RR 141 pada seluruh tanah liat lokal yang diteliti sesuai dengan model pseudo second order. Data kesetimbangan adsorpsi RR 141 pada tanah liat Arcamanik paling baik digambarkan oleh model isoterm Freundlich sedangkan untuk tanah liat Citatah dan Dago paling baik digambarkan oleh model isoterm Langmuir. Nilai perubahan energi bebas pada tanah liat Arcamanik, Citatah dan Dago masing-masing sebesar -4,794; -7,048 dan -4,234 kJ/mol.