The thermal decomposition of the microalgae Spirulina platensis, synthetic wastes, and their blends under an oxidative atmosphere and their kinetic parameters were investigated using a thermogravimetric analyzer. Three stages were observed during the combustion of the blended fuels, and two distinct peaks occurred in the second stage. A kinetic analysis during combustion was studied according to the fitting method proposed by Coats-Redfern and Horowitz-Metzger. The addition of the microalgae to the synthetic waste led to an increase in the apparent activation energies in Zone I in the second stage, whereas an increasing proportion of the microalgae in the blends resulted in decreasing apparent activation energies in Zone II in the second stage.

Working fluids in heat exchanger commonly used water or ethylene glycol with their advantages and disadvantages. There was a development to disperse nanoparticles into base fluids, or known as nanofluids, to resolve the disadvantages of the working fluid. Nanoparticles gave fluids unique characteristics including an increase in heat transfer. Therefore, nanofluids had better heat transfer characteristics compared to conventional working fluids. This article discussed the effect of adding nanoparticles in TiO₂-ethylene glycol nanofluid towards the heat transfer characteristics (Nusselt, Reynolds, ΔT LMTD, convective coefficient, overall heat transfer coefficient, and heat transfer) using heat exchanger device. The variation of nanoparticle concentrations in this research were 0%, 0.025%, 0.05%, and 0.075%. This research used laboratory-scaled heat exchanger type shell and tube as the heat transfer device, with the volumetric flow rate variations of 0.2, 0.4, and 0.6 l/m for each nanofluid sample. The test results showed that there was an increase along with the increasing nanofluid volumetric flow rate and the new nanoparticle concentrations.

In order to assess the impact of the Sanitation by Communities (SANIMAS) program for community-led sanitation in Indonesia (established in 2002), this research work was conducted with the aim of characterizing the current performance of anaerobic baffled reactors (ABRs), which were deployed in high numbers for the provision of domestic wastewater treatment in densely populated urban areas in Malang (Indonesia). Small and decentralized sewage treatment facilities serve ≈3% of the total population in Malang, including 89 ABR treatment plants. Our findings reveal that only 14% of the 89 ABRs in Malang have an acceptable performance with regard to pollutant removal and integrity of their building structure, but the majority of them produce a treated effluent of poor quality, according to discharge consents set by the Ministry of Environment and Forestry of the Republic of Indonesia (Regulation No. P.68/2016). Clearly the lack of consistent operation and maintenance practices have had a detrimental effect on these decentralized sewage treatment systems, despite their robustness and buffer capacity to cope with changes in organic and hydraulic loading rates. Urbanization will continue to exert pressure on the provision of sanitation services in lower and middle economies, and the role of decentralized sewage management systems is expected to be prominent in the UN’s Sustainable Development Goals era (2015–2030); however, sustainable service delivery must be conceived beyond the provision of sanitation infrastructure.

Zinc ferrite (ZnFe2O4) nanoparticles have attracted the attention of researchers because of their unique chemical properties and particle-size-dependent magnetic properties. High-surface-area spinel ferrites have numerous technical applications in areas such as high-density information storage, ferrofluids, and catalysis. The coprecipitation technique is the preferred method for preparing nanoscale ZnFe2O4 because it results in a small crystals with a uniform size distribution. In this study, the synthesis was conducted in solution for 48 h, followed by sintering at 1000°C for 1.5–3.5 h. The smallest crystals (70.58 nm) were found in the sample sintered for 2.5 h. Fourier transform infrared spectroscopy (FTIR) functional-group analysis confirmed the presence of Fe–O and Zn–O bonds of cations in octahedral and tetrahedral sites. The ZnFe2O4 sintered for 3.5 h was superparamagnetic. The characterization results suggest that the obtained ZnFe2O4 could be used as a nanofluid in heat exchangers.

The potential of municipal solid waste (MSW) in Malang City Indonesia was investigated in term of its physicochemical properties and thermal behavior. The proportional mixed of the organic-inorganic sample was tested its chemical content by using Energy-dispersive X-ray (EDX) spectrometry. The physical properties (moisture, volatile matter, fixed carbon, ash content as well as calorific value) was studied by using standard ASTM test method.The thermal behavior of the sample was characterized by thermogravimetric technique. Results showed that C and O were the main elements which encountered in the sample. The inorganic ingredients were dominated by Al, Ti, Si, Fe, K and Ca respectively. The MSW shows low moisture (4,69 wt%, adb), ash (5.51 wt%, db) and fixed carbon (8.29 wt%, db), whereas high volatile matter (86.20 wt%, db). The calorific value of MSW was comparable to the middle class of the coal (25.78 MJ/kg). Three stages decomposition were encountered during thermal test become a fundamental data to design a proper combustion system.