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All Journal Reaktor Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan GeoEco
Wahyono, Yoyon
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Agriculture, Biological Sciences & Forestry Chemical Engineering, Chemistry & Bioengineering Control & Systems Engineering Earth & Planetary Sciences Education Energy Environmental Science Materials Science & Nanotechnology Social Sciences

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The Dynamics Impact of Urban Area on the River Health in Surakarta City Firdausi, Eyda; Matin, Hashfi Hawali Abdul; Budiyono, Budiyono; Wahyono, Yoyon; Othman, Nur Hidayati
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Vol 22, No 1 (2025): March 2025
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/presipitasi.v22i1.209-220

Abstract

Surakarta City is traversed by the Bengawan Solo River Sub-Basin which includes Kali Pepe River, Gajah Putih River, Kali Anyar River, Jenes River, and Premulung River. This condition results in the main burden of river water pollution coming from anthropogenic activities, both domestic and industrial. This study aims to examine the influence of urban area dynamics on river health with a case study of Surakarta City. This study used qualitative descriptive method. Data collection was carried out through observation techniques, and depth interviews. The results showed that there are three factors that affect river health, namely population increase, industrial and domestic activities, and public perception and participation. Surakarta City is one of the areas that contributes to river pollution from moderate to severe levels. However, there have been many efforts to evaluate river health by the local government, namely by normalizing riverbanks, controlling waste pollution, and other river management programs. 
Incorporating silica synthesized from rice husk ash into a calcium oxide catalyst for biodiesel production Alhanif, Misbahudin; Mustafa, Mustafa; Kumoro, Andri Cahyo; Wahyono, Yoyon; Zaim, Hanif Fawwaz; Zahra, Nurul Afifah
Reaktor Volume 25 No.2 August 2025
Publisher : Department of Chemical Engineering, Faculty of Engineering, Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/reaktor.25.2.58-69

Abstract

Biodiesel represents a promising renewable energy alternative to either substitute or be blended with conventional diesel, offering advantages such as a high cetane number, reduced sulfur (SOx) and CO₂ emissions, and greater environmental sustainability. The application of calcium oxide (CaO) as a basic catalyst in biodiesel production has been extensively reported. However, its catalytic performance is limited by its sensitivity to moisture, which can negatively affect the reaction rate. In addition, some of the Ca2+ ions in the catalyst can dissolve in the mixture of biodiesel and glycerol, causing product contamination. This study aims to combine a CaO catalyst from marble powder with sulfonated silica (SiO2) from rice husk ash (RHA) to enhance the distribution of catalyst particles, reduce crystallinity, and increase the surface area of the catalyst. This study was conducted through chemical and thermal activation of SiO2 from RHA, sulfonation of SiO2, thermal activation of CaO from marble powder waste, and impregnation of CaO/SiO2 catalyst with variations in CaO/SiO2 composition (25%:75%, 50%:50%, 75%:25%). The results showed that the purity of SiO2 and CaO obtained through chemical and thermal activation was 93.67% and 99.13%, respectively. The sulfonation process on SiO2 successfully added –SO3 groups at 36.5%, which supported the formation of acid sites on the catalyst. Characterization showed that the surface morphology was composed of particles measuring 2–8 µm with a dominant amorphous structure. The addition of SiO2 gave rise to new crystal peaks but decreased the crystal intensity, especially at the 50%:50% composition. The composition of CaO/SiO2 at 75%:25% showed the best physical properties with a surface area of 22.24 m²/g, a pore volume of 65.29 mm³/g, and a pore diameter of 11.74 nm, indicating high potential as a bifunctional catalyst for biodiesel esterification–transesterification.
Cellulose Hydrolysis of Mask Waste Using Aspergillus niger and Eco-Friendly Microwave Pretreatment Gilbran, Adam; Nafilah, Syahraini; Layalia, Afina Rista; Arsyad, Wifqul Muna; Darmawan, Andi; Setiawan, Risqi Prastianto; Irviandi, Risnu; Kusdiyantini, Endang; Nurauliyaa, Aida Habibah; Anda, Martin; Sasongko, Nugroho Adi; Wahyono, Yoyon
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Vol 22, No 3 (2025): November 2025
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/presipitasi.v22i3.993-1001

Abstract

The management of used medical mask waste has become a significant issue due to the increased volume of waste during and after the pandemic. Medical mask waste contains cellulose compounds that can be converted into derivatives such as glucose, which are then processed into bioethanol as an alternative energy source. This study aims to hydrolyse medical mask waste using cellulase enzymes from Aspergillus Niger to produce glucose. The cellulase enzyme composition was varied (5 ml, 15 ml, and 25 ml) to determine the optimal hydrolysis conditions. The glucose produced was measured using DNS reagent assay with spectrophotometry at a wavelength of 540 nm. The highest amount of glucose was obtained under optimal conditions with 25 ml of cellulase enzyme after 48 hours of hydrolysis, amounting to 88.16 ppm. Subsequently, the glucose from hydrolysis was fermented using Saccharomyces cerevisiae, and the fermentation product was analysed for ethanol concentration using GC-FID. The products of fermentation ware 0.017% ethanol concentration from mask waste fermentation. Hydrolysis is an environmentally friendly alternative solution for handling mask waste.
Environmental Impact of Energy Diversification Using Refuse-Derived Fuel in Cement Industry Firdausi, Eyda; Abdul Matin, Hashfi Hawali; Rachmawati, Siti; Wahyono, Yoyon; Purwono, Purwono; Budiyono, Budiyono; Kencanawardhani, Larasati Gumilang
Jurnal Presipitasi : Media Komunikasi dan Pengembangan Teknik Lingkungan Vol 23, No 1 (2026): March 2026
Publisher : Universitas Diponegoro

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.14710/presipitasi.v23i1.175-187

Abstract

Processing municipal solid waste into refuse-derived fuel (RDF) is an alternative solution to the waste problem. This study determined the potential environmental impact of Sleman RDF as an energy diversification agent in the cement industry using life cycle assessment (LCA). The boundary system of this study is gate-to-grave, with a functional unit of co-firing energy requirements for the production of 1 metric ton of clinker. Two clinker co-firing scenarios were developed, involving a combination of coal and alternative fuels. The results showed that the production of 1 metric ton of clinker requires a large amount of resources and contributes significantly to climate change, ecosystem toxicity, and human toxicity. Co-firing clinker in the alternative scenario successfully reduced the potential environmental impact by 14% with a thermal substitution rate of 20%. The findings of this study indicate that RDF is effective in reducing dependence on fossil fuels and lowering emissions and the potential environmental impact.
DISTRIBUTION OF URBAN HEAT ISLAND INDEX IN THE SURABAYA, YOGYAKARTA, AND BANDUNG USING REMOTE SENSING Candraningtyas, Callista Fabiola; Matin, Hashfi Hawali Abdul; Suhardono, Sapta; Wahyono, Yoyon
GeoEco Vol 11, No 1 (2025): GeoEco January 2025
Publisher : Universitas Sebelas Maret (UNS)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.20961/ge.v11i1.95660

Abstract

Climate change is a global issue as it drives global warming and heightens the impact of greenhouse gases. In the past decade, the Urban Heat Island (UHI) phenomenon has become a growing concern in major cities due to urbanization and development. This study aims to analyze the distribution and relationship between changes in Land Surface Temperature (LST), Normalized Difference Vegetation Index (NDVI), and Normalized Difference Built-up Index (NDBI) with UHI changes in Surabaya, Yogyakarta, and Bandung, and propose mitigation strategies. The descriptive quantitative approach is used in the research to explain the calculated area and percentage of NDVI, NDBI, LST, and UHI. Geographic Information System (GIS) technology, specifically ArcGIS 10.8, was utilized to process Landsat imagery data from 1994 and 2024, enabling spatial analysis and visualization of urban heat distribution and land use changes. Simple correlation analysis was also carried out to examine the relationship between LST and NDVI, as well as LST and NDBI. The analysis shows that NDVI decreased, while NDBI, LST, and UHI increased over the 30 years in all three cities. LST and NDVI have a strong inverse relationship, where increasing LST correlates with decreasing NDVI. NDBI shows a positive relationship with LST, meaning more built-up areas lead to higher LST and UHI. Mitigation strategies include expanding green spaces, adopting green building technologies, and utilizing renewable energy.
Co-Authors Abdul Matin, Hashfi Hawali Anda, Martin Andi Darmawan Andri Cahyo Kumoro Arsyad, Wifqul Muna Budiyono Budiyono Candraningtyas, Callista Fabiola Endang Kusdiyantini Firdausi, Eyda Gilbran, Adam Irviandi, Risnu Kencanawardhani, Larasati Gumilang Layalia, Afina Rista Matin, Hashfi Hawali Abdul Misbahudin Alhanif Mustafa Nafilah, Syahraini Nugroho Sasongko Jati, Nugroho Sasongko Nurauliyaa, Aida Habibah Othman, Nur Hidayati Purwono Purwono, Purwono Setiawan, Risqi Prastianto SITI RACHMAWATI Suhardono, Sapta Zahra, Nurul Afifah Zaim, Hanif Fawwaz