Frontiers in assessing septic systems vulnerability in coastal Georgia, USA: Modeling approach and management implications

Threats to public health and environmental quality from septic systems are more prevalent in areas with poorly draining soils, high water tables, or frequent flooding. Significant research gaps exist in assessing these systems’ vulnerability and evaluating factors associated with higher rates of septic systems replacement and repair. We developed a novel GIS-based framework for assessing septic system vulnerability using a database of known septic system specifications and a modified Soil Topographic Index (STI) that incorporates seasonal high groundwater elevation to assess risks posed to septic systems in coastal Georgia. We tested the hypothesis that both the modified STI and septic system specifications such as tank capacity per bedroom and drainfield type would explain most of the variance in septic system repair and replacement using classification inference tree and generalized logistic regression models. Our modeling results indicate that drainfield type (level vs. mounded) is the most significant variable (p-value < 0.001) in predicting septic systems functionality followed by septic tank capacity per bedroom (p-value < 0.01). These show the importance of septic system design regulations such as a minimum requirement for horizontal separation distance between the bottom of trenches and seasonal water table, and adequate tank capacity design. However, for septic systems with a mounded drainfield and a larger tank capacity per bedroom, the modified STI representing hydrological characteristics of septic system location is a significant predictor of a high septic system repair and replacement rate. The methodology developed in this study can have important implications for managing existing septic systems and planning for future development in coastal areas, especially in an environment of rapid climatic change.

Theoretical Efficiency and Practicality of the Solar Trough Collector / Tikrit-Iraq

An experimental and theoretical study was conducted to attain solar collectors’ thermal efficiency. Testing was done during May of 2019 on a solar collector’s surface at the Physics Department of the University of Tikrit. The absorbent tubes used had a length of 1.5 m, were painted black, made of copper, had an outer diameter of 0.03 m, internal diameter of 0.028 m, and a tank capacity of 40L. By entering these specifications along with those of the solar collector, the theoretical thermal efficiency was calculated. The findings showed that practical efficiency curves and useful thermal energy absorbed by the water contained goes down when using copper tubing. The results also illustrated that useful thermal energy and thermal efficiency increases along with increasing the mass flow rate of water.

Techno-Economic Optimization of Medium Temperature Solar-Driven Subcritical Organic Rankine Cycle

The present work focuses on the techno-economic assessment and multi-objective genetic algorithm optimization of small-scale (40 kWth input), solar Organic Rankine Cycle (ORC) systems driven by medium-to-high temperature (up to 210 °C) parabolic dish (PDC) and trough (PTC) collectors. The ORCs are designed to maximize their nominal thermal efficiency for several natural hydrocarbon working fluids. The optimization variables are the solar field area and storage tank capacity, with the goal of minimizing the levelized cost of produced electricity (LCoE) and maximizing the annual solar conversion efficiency. The lowest LCOE (0.34 €/kWh) was obtained in Athens for a high solar field area and low storage tank capacity. Meanwhile, the maximum annual solar conversion efficiencies (10.5–11%) were obtained in northern cities (e.g., Brussels) at lower solar field locations. While PTCs and PDCs result in similar efficiencies, the use of PTCs is more cost-effective. Among the working fluids, Cyclopentane and Cyclohexane exhibited the best performance, owing to their high critical temperatures. Notably, the systems could be more profitable at higher system sizes, as indicated by the 6% LCoE decrease of the solar ORC in Athens when the nominal heat input was increased to 80 kWth.

Vertical tank capacity measurement based on Monte Carlo method

Vertical tanks are commonly used appliances for liquids, and its capacity is very important for quantitative liquid ratio and liquid trade. In order to measure the capacity of vertical tanks more conveniently, this paper proposes a vertical tank capacity measurement method based on Monte Carlo Method. The method arranges a plurality of sensor points on the inner surface of the tank, and then performs Monte Carlo tests by generating a large number of random sample points, and finally calculates the capacity by counting the sample points that meet the criterion. The criterion for whether a sample point is located in the tank, which is the core issue, is established with the coordinates of sensor points and the distance between different sensor points along the surface of the tank. The results show that the absolute error of the measurement results of the proposed method does not exceed ±0.0003[m3], and the absolute error of capacity per unit volume has a linear relationship with the height of the vertical tank, and has little effect with the radial size of the vertical tank.

Potential for Potable Water Savings Due to Rainwater Use in a Precast Concrete Factory

The objective of this paper was to assess the potential for potable water savings due to rainwater use in a precast concrete factory in southern Brazil. The economic feasibility and the rainwater quality were also assessed. The current water consumption, future water demand, and rainwater demand in the factory were estimated. The future demand considered was two times higher than the current water consumption since there were plans to increase the production. Three scenarios were then simulated using the computer programme Netuno. The ideal rainwater tank capacity, the potential for potable water savings, and the economic feasibility analysis for each scenario were estimated. Samples of rainwater were collected in the factory and tested for quality for manufacturing precast concrete. For a rainwater tank capacity equal to 25,000 L, the potential for potable water savings for the first scenario was 55.4%, but the first scenario was considered economically unfeasible. For the same tank capacity, the second and third scenarios presented viable results regarding potable water savings and payback. As for the rainwater quality, it was proven to be adequate for manufacturing precast concrete. The main conclusion was that rainwater can be used to manufacture precast concrete in the factory studied herein.

Potential for Potable Water Savings Due to Rainwater use in a Precast Concrete Factory

The objective of this paper is to assess the potential for potable water savings due to rainwater use in a precast concrete factory in southern Brazil. The economic feasibility and the rainwater quality were also assessed. The current water consumption, future water demand and rainwater demand in the factory were estimated. The future demand considered was two times higher than the current water consumption since there are plans to increase the production. Three scenarios were then simulated using the computer programme Netuno. The ideal rainwater tank capacity, the potential for potable water savings and the economic feasibility analysis for each scenario were estimated. Samples of rainwater were collected in the factory and tested for quality for manufacturing precast concrete. For a rainwater tank capacity equal to 25,000 litres, the potential for potable water savings for the first scenario was 55.4%, but the first scenario was considered economically unfeasible. For the same tank capacity, the second and third scenarios presented viable results regarding potable water savings and payback. As for the rainwater quality, it was proven to be adequate for manufacturing precast concrete. The main conclusion is that rainwater can be used to manufacture precast concrete in the factory studied herein.

Logika Fuzzy dengan Metode Mamdani dalam Menentukan Tingkat Peminatan Tipe Motor Honda

Honda motorcycles are in demand by the public as a cheap means of land transportation. CV Hayati is the main motorcycle dealer company in Padang. In carrying out its activities, CV Hayati needs to consider several factors when selling motorcycles that are in demand by consumers. However, CV Hayati still uses manual means in looking at the interest in the motor that will be purchased by consumers. To solve the problem, a system is needed that can help with decision-making by consumers in purchasing motors according to their interests. In this study, the decision to buy a motor that consumers were interested in was done using the fuzzy logic of mamdani method. With the decision-making system in motor interest, it is expected to help and facilitate consumers in determining the motor they are interested in buying. The results of this study can be viewed using the PHP programming language and MySQL database, with the fuzzy logic of the mamdani method. Where in the fuzzyfication process consider several input variables namely: price, oil fuel tank capacity, engine speed, baggage capacity and vehicle weight. So that by defuzzification can be determined the recomedation of motors that are in demand by consumers.