Heating, Ventilating, and Air Conditioning (HVAC) is a system to condition indoor air by cooling or heating to achieve thermal comfort for a human being. The HVAC system operates based on the refrigeration cycle, where heat is dissipated from the condensing unit in the warm air arrangement. This represents an ironic foundation of heat that might be recovered for further schemes or applications. In this paper, experimental work was developed to validate the proposed heat recovery system using heated air released from the condenser unit of the HVAC system as a source for the air dryer for the drying rack. Four different output parameters are to be observed in this research: the dry-bulb temperature of the air exit from the condenser unit, the dry-bulb temperature of the air inflowing the dryer, and the drying time and the relative humidity of the air leaving the dryer. These experimental works were conducted using a domestic application of a 1.0 hp air conditioning (AC) system with R-22 refrigerant gas and based on the following factors: The three-variant mass of wet clothes, the three-stage of mechanical fan speed for releasing warm air from the condenser, and the effect of variable ambient or surrounding air dry-bulb temperature were studied. A physical prototype of the dryer was constructed for proof-of-concept purposes. The experimental output was then analyzed to obtain precision and accurate data. To determine the system behavior, a refrigeration cycle analysis was conducted. It has been shown that an AC system of 1.0 hp can cover wet clothes drying of weights 1950 g, 4255 g, and 6350 g at 55, 80, and 110 min with a constant air velocity of 0.34 m-3.s-1 in an ambient temperature of 33°C. The significant contribution of this research is the proposed heat-recovery-based air dryer system with the capability to increase the Coefficient of Performance (COP) of the AC unit from 2.36 to 2.70. Hence, the energy-saving was received using the heat-recovered-based air dryer instead of a commercial electric air dryer system that uses high power consumption from their heater element.

The requirement for a renewable and environmentally gracious alternative resource of energy has grown in recent years as a result of increased knowledge of the negative impacts of petroleum-based fuels on the environment and the regular rise in crude oil prices. Biodiesel has been proven to be the ideal replacement for diesel because of its unique qualities, such as a huge decrease in greenhouse gas emissions, nonparticulate matter pollutants, non-sulfur emissions, less toxicity, and degradability. This article examines the pre-treatment stage, the physiological and chemical features of WCO, transesterification, esterification, and the manufacturing of biofuel from waste-cooked oil using several techniques and catalyst types. The elements that influence the stated process parameters are investigated, with a particular focus on the methanol to oil ratio (molar ratio), time of reaction, the temperature of the reaction, catalyst percentage, and yield of biodiesel. After the production of biodiesel, we can optimize the process parameters, for example, methanol to oil ratio, the temperature of the reaction, duration of reaction, and catalyst percentage, and also optimize the yield of biofuel generation with the CCD design of the Response surface methodology (RSM) algorithm using Design Expert software.

Municipal solid waste (MSW) continues to be a major challenge in almost every country. In Indonesia alone, approximately 64 million tons of MSW are produced on an annual basis. While polyethylene terephthalate (PET) bottles account for 12% of all plastic products, the waste is not well managed. Many stakeholders are involved in PET bottle waste recycling but no forum for stakeholders has been established. In this study, the aim is to identify an acceptable system for PET bottle waste, to determine the role and function of each stakeholder, and to propose a framework under the perspective of public-private partnerships. The study’s novelty is the elaborate roles and schematic framework for various stakeholders in PET bottle waste. The aim is to identify an acceptable scheme for PET bottle waste and determine each stakeholder’s role and function. Data was generated from electronic databases (2017 to December 2021) a systematic literature review methodology followed by Preferred Reporting Items for Systematic review. The data were analyzed by the Meta-Analysis (PRISMA) approach. This study found that the laws and regulations for waste management in Indonesia are not suitable for dealing with PET bottle waste, and the government carries out limited tasks and dedicates few resources to managing the waste. A public-private partnership framework was proposed to divide the role, commitment, goal, and activities of each stakeholder to properly manage PET bottle waste.

There is a pressing need for new nanomaterials for multipurpose functions. The biological synthesis of nanoparticles is environment-friendly, least toxic, and cost-effective. An experiment was designed to use extracellular amylases in the cell-free filtrate (CFF) for the biosynthesis of silver nanoparticles (AgNPs) from the Trichoderma harzianum MTCC 801 strain. Potato dextrose broth (PDB) as general-purpose growth media and amylase production media (APM) as enzyme-specific production media have been used for sub-merged fungal cultivation and nanoparticle synthesis. AgNPs synthesized in the CFF of PDB were compared with AgNPs synthesized from the CFF using APM. The cell-free filtrate obtained upon enzyme stimulation has contributed to the reduction and capping process of nanosilver. The synthesized AgNPs showed a spectral peak at 420 nm, a characteristic feature of AgNPs. The particles were monodispersed, 50 nm in size, and spherical in shape as well as have shown an antifungal effect (100% inhibition) against Sclerotinia sclerotiorum MTCC8785. This is the first report to synthesize trichogenic AgNPs using extracellular amylases against the phytopathogen Sclerotinia strain.

This paper takes Poa annua L. as the research object and studies the law of physiological and ecological stress of 1-Chloronaphthalene (CN-1) and Octachloronaphthalene (CN-75) by using various physiological and biochemical indexes of Poa annua L. cultivated with soil under the stress of CN-1 and CN-75 of different concentrations. According to the research, the chlorophyll a and b first increase and then decrease with the increase of the concentration of CN-1, and continue to decrease with the increase of CN-75; Soluble sugar and soluble protein in plants decrease first and then increase with the increase of CN-1, and continue to decrease with the increase of CN-75; MDA in plants increases first and then decreases with the increase of the concentration of CN-1 and CN-75. The proline content in plants also increases first and then decreases with the increase of concentration of CN-1 and CN-75. Based on the research, it can be seen that the tolerance of the plant to CN-75 is not good as to CN-1.

The objective of the research was to evaluate the effect of geographic altitude on the carbon stock in two physiographic units of the Reserved Forest of the Universidad Nacional Agraria de la Selva, Tingo Maria-Huanuco. The methodology used was the field manual for the remeasurement and establishment of plots of the Amazon Forest Inventory Network (RAINFOR), for which 2 hectares were permanently established (one hectare in low and high hills) in which the diameter (greater than or equal to 10 cm) and the height of the trees were measured. Finally, the density of the wood was obtained from previous studies. The pantropical model formula was used to estimate the carbon stock. The results show that geographic altitude significantly affects carbon stock (p < 0.05) in low and high-hill forests, concluding that this may be due to differences in meteorological variables such as precipitation, temperature, and humidity.

Septage comprises the solid and liquid constituents of any primary treatment system, including a Septic Tank. In this study, the wastewater collected from a septic tank is passed through a partially converted anaerobic filter, and a vertical flow constructed wetland (VFCW) before being sent to a soak pit. The main objective of this case study was to check the effectiveness of incorporating a VFCW between a septic tank and a soak pit to bring down the consequences created due to effluent seepage from soak pits to the groundwater. Conventionally, the effluent gets directly passed to soak pits after primary onsite treatment in the septic tank. The soak pit walls made of porous materials allow the gradual seepage of final effluent into the ground, polluting the groundwater reserves. We analyzed the septic tank effluent from 60 households wherein the effluent was let off into the soak pits. The various parameters analyzed with their averages were 393.83 ± 293.41 mg.L-1 for COD, 151.48 ± 94.37 mg.L-1 for BOD, 30.81 ± 13.05 mg.L-1 for NO3-, 23.35 ± 13.54 mg.L-1 for PO43-, 7.35 ± 0.31 for pH, 184.05 ± 163.20 mg.L-1 for TSS, 3.05 x 107± 2.04 x 108 CFU.100mL-1 for TC. Therefore, it is certain that the final effluent being sent into soak pits after primary treatment does not meet the Central Pollution Control Board (CPCB) discharge standards. In this case study, we were able to obtain final effluent values after VFCW treatment as 55.72 mg.L-1 for COD, 12.12 mg.L-1 for BOD, 10.2 mg.L-1 for NO3-, 3.74 mg.L-1 for PO43-, 7.41 for pH, 8.37 mg.L-1 for TSS, 379.27 mg.L-1 for TS and 51.9 CFU.100mL-1 for TC. With this case study, we were able to resolve this impediment by bringing down the values of all the parameters considered while analyzing under the limits of discharge standards set by CPCB. The removal efficiency of COD, BOD, NO3-, PO43-, pH, TSS, and TC after wetland was found to be 89.46%, 88.051, 63.484, 44.37%, 3.41%, 98.47%, 97.71%, 97.19% respectively. The study has proven that with the introduction of another decentralized treatment system between a septic tank and soak pit, it is safe to dispose of the effluent into soak pits, thereby reducing the chances of groundwater pollution considerably.

The disposal of the huge volume of glass waste is one of the significant environmental issues that need to be addressed. One of the efficient ways to solve this problem is to incorporate ground glass waste in concrete mixtures. However, its inherent surface smoothness and microcracks within the glass particle harm the hardened properties of concrete. Minimizing the particle size and controlling the amount of cement in the mixture can reduce the adverse effect of using glass in concrete. This study utilized ground glass waste (850 μm) as aggregate filler in a concrete mix. More specifically, this study investigated the effect of paste volume (Vp) on the properties of fresh and hardened concrete with ground glass waste as aggregate filler. Based on the test results, ground glass waste as aggregate filler negatively affects the workability of fresh concrete, but increasing the amount of paste can mitigate it. Vp values in terms of void volume (Vv) in the aggregates of 1.6Vv and 1.8Vv achieved satisfactory consistency of fresh concrete. In addition, the concrete compressive strength increased when increasing Vp. The test results have shown that ground glass waste has the potential to be utilized as aggregate filler in concrete mixtures.

The present study aimed to find a relationship between turbidity removal percent in tube settler clarifier and independent variables (tube inclination, alum dosage, and surface loading rate) by constructing a statistical model and categorizing these explanatory variables according to their impact on turbidity removal percentage. A pilot scale of tube settlers was designed and fabricated to conduct the experiments. It consisted of a coagulation and flocculation basin, pre-tube settler chamber, and tube settler. Alum was used to coagulate the Tigris river raw water at different dosages. After flocculation, water is transferred to the pre-tube settler chamber and flows through the tube settler. It consists of four tubes of square section, 4 centimeters in diameter, with the flexibility of changing tube length and inclination angle to obtain different levels of surface loading rate. More than 120 experiments were conducted, and the results were analyzed statistically. A regression model was found with a coefficient of determination of 0.802 between turbidity removal percentage as a dependent variable and each tube inclination, alum dosage, and surface loading rate as independent variables. The model is considered good as the model’s relationship between actual and predicted values has a slope of one and a constant near zero. Surface loading rate has the highest effect on turbidity removal percentage with 4.44 times that of inclination angle and 2.5 times for the optimum alum dosage model. The study concluded that the linear model is suitable to represent the performance of tube settlers at optimum alum dosage.

Agro-waste can provide a non-metallic, environmentally friendly bio-precursor for the production of green silica nanoparticles. To manufacture silica nanoparticles from rice husk, biogenic silica nanoparticles were generated using an alkaline precipitation approach. Rice husk as a source of silica nanoparticles is environmentally and economically valuable because it is a plentiful lower price agricultural derivative that can be used to help with waste management. During the synthesis process, the dose of rice husk ash was used at 5 g at pH 7, alkali dose concentration of 0.5 M, reaction period of 3.5 h, and temperature of 90°C that produced maximum silica nanoparticles with a yield of 88.5%. To optimize the silica nanoparticle production from rice husk ash Box Behnken Design (BBD) a subcategory of the response surface methodology (RSM) was accomplished. BBD model was successfully matched, as evidenced by the high correlation values of adjusted R2 0.9989 and predicted R2 0.9977. Silica nanoparticles’ amorphous form generated from rice husk ash is indicated by XRD analysis 2Ө peak at 22.12° and UV-Vis Spectroscopy absorbance peak at 312 nm. The amorphous shape of silica is amorphous and crystalline defined through XRD. nanoparticles generated from rice husk ash is indicated by FESEM analysis and EDX analysis, confirming that the SiO2 elemental configuration comprises the highest concentration of Si and O. The existence of a siloxane group in the produced compound was revealed by FTIR spectra stretching vibrations at 803.69 and 1089.05 cm-1