Performance Evaluation of Textile Effluent Treatment Plant: Bangladesh Perspective

The present study was undertaken to evaluate the performance efficiency of an Effluent Treatment Plant (ETP) of a Textile industry located at Tongi, Bangladesh with biological treatment (BT) and Membrane Bio-Reactor (MBR) with an average inflow of 300 m3/hr. The effluent samples were collected from the inlet and outlet of the ETP on a weekly basis for a 4 weeks’ period and were analysed for key parameters such as colour, temperature, total suspended solids (TSS), Total Dissolved Solids (TDS), pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), and Chemical Oxygen Demand (COD). In this study, it was observed that the colour of the effluent in the inlet was dark blue and after multiple unit treatments of the colour’s final outlet the discharge, water colour was very light purple. The temperature was varied from 32.2⁰C to 34.33⁰C. The TDS was varied from 1252.5 mg/l to 1087.5 mg/l and the percentage removal efficiency of TDS was varied from 21.47% to 42.7%. The TSS was varied from 4 mg/l to 4.5 mg/l and the percentage removal efficiency of TSS was varied from 98.48% to 98.21%. The pH value was varied from 6.48 to 7.63. The DO value in the inlet was varied from 6.47 mg/l to 6.775 mg/l. The BOD was recorded from 12.75 mg/l to 17.75 mg/l and the percentage removal efficiency of BOD was varied from 89.92% to 87.24%. The COD was varied from 33.75 mg/l to 34.25 mg/l and the percentage removal efficiency of COD was varied from 91.11% to 90.5%. It is conjectured that the values of the measured parameters are seen to be within the permissible limit as per the standard of the Department of Environment (DoE) of Bangladesh.

Effects of Removal Conditions on Mercury Amount Remaining in the Oral Cavity and inside Drainage System after Removing Dental Amalgams

Mercury is produced and drained into the environment by removing dental amalgams, which may cause mercury pollution. This study aimed to clarify the mercury amount remaining in the oral cavity and inside the drain system after removal. The effects of the removal conditions and differences in drainage systems were also investigated. Dental amalgams filled in the tooth and placed in a phantom head were removed using an air turbine under several conditions (two removal methods, absence of cooling water, and intraoral suction). Then, the oral cavity was rinsed with 100 mL of water (oral rinse water), and 500 mL of water was suctioned to wash the inside of the drainage system (system rinse water). Both water samples were collected in two ways (amalgam separator and gas-liquid separator), and their mercury amounts were measured. It was found that the amount of mercury left in the oral cavity and drainage system after dental amalgams removal could be reduced when the amalgams were removed by being cut into fragments as well as using cooling water and intraoral suction. In addition, using amalgam separators can significantly reduce the amount of mercury in the discharge water and prevent the draining of mercury into the environment.

Bilge System Design on 500 GT Ferry for Bulukumba–Selayar Route

A piping system is the main part of a system that connects the point where the fluid is stored to the point of accessing the pipe. Both pipe strength and pump capacity must be carefully considered because the safety of a ship will depend on the piping arrangement as well as on other ship equipment. The main function of the bilge pipe system is the drainage system in case of flooding in the compartment due to grounding or collision. Another function is the drainage system in the event of leaks on the welding root, condensation on the side shell leaks on the piping system (particularly in the engine room), and discharge water due to water-splash over the hatch. This study aimed to design a bilge piping system design using Autopipe Software with ASME B31.3 standard for the piping process. The design phase of the system is collecting data, then determining the load case. After that, selecting components needed for the construction of the system. The following step, making 3-dimensional modeling on Autopipe by entering input based on the determining components. Finally, validating the model, and proceed with the running model according to the specified load case. The result of the running model is the pipe stress level which is described in the stress code in the Autopipe. The final results are 3-dimensional drawings of the system and the number of components needed for constructing the system under Indonesian Classification Bureau (BKI) rules and ASME B31.3 standards for the piping process.

Hydrogeological explanation of seepage diseases in stone grottoes: a case study of Maijishan Grottoes, China

This research studied the seepage diseases (water discharge and salt precipitation) in Maijishan Grottoes from the perspective of hydrogeology. Maijishan Grottoes is one of the extent large group of grottoes in China, where its cliff, on mount Maiji, the carrier of the grottoes, has been reinforced by concrete cover in a large area. As a case study, the physical and chemical processes of the seepage are deduced through the relationships between the flow rate of discharge water (DW) and precipitation, and through the water chemistry diversity including pH, electrical conductivity (EC), and Ionic composition between DW and rainwater (RW) and a controlled spring water (SW). Constructive results are obtained. Firstly, a perched aquifer is confirmed in the mount. All the RW will gather at the aquifer, and then discharge through 3 independent routes that connect the aquifer and grotto site. 3 kinds of water discharge response to precipitation are defined to correspond to the 3 routs: Immediate Response (I.Resp), Delay Response (D.Resp), and Stealth Response (S.Resp), these responses make up the majority of the DW. On the other hand, 2-staged chemical evolution is also been confirmed during the seepage, where stage I took place in the aquifer and stage II took place at shallow, the concrete only participate in the chemical evolution at stage II, resulted in high pH [7.77, 11.69] and EC [513, 3540] (µS/cm) in DW compared to the SW and RW.

Modelling to Lower Energy Consumption in a Large WWTP in China While Optimising Nitrogen Removal

In the last decade, China has sharply tightened the monitoring values for wastewater treatment plants (WWTPs). In some regions with sensitive discharge water bodies, the values (24 h composite sample) must be 1.5 mg/L for NH4-N and 10 mg/L for total nitrogen since 2021. Even with the previously less strict monitoring values, around 50% of the wastewater treatment plants in China were permanently unable to comply with the nitrogen monitoring values. Due to the rapid changes on-site to meet the threshold values and the strong relation to energy-intensive aeration strategies to sufficiently remove nitrogen, WWTPs do not always work energy-efficiently. A Chinese WWTP (450,000 Population equivalents or PE) with upstream denitrification, a tertiary treatment stage for phosphorus removal and disinfection, and aerobic sludge stabilisation was modelled in order to test various concepts for operation optimisation to lower energy consumption while meeting and undercutting effluent requirements. Following a comprehensive analysis of operating data, the WWTP was modelled and calibrated. Based on the calibrated model, various approaches for optimising nitrogen elimination were tested, including operational and automation strategies for aeration control. After several tests, a combination of strategies (i.e., partial by-pass of primary clarifiers, NH4-N based control, increase in the denitrification capacity, intermittent denitrification) reduced the air demand by up to 24% and at the same time significantly improved compliance with the monitoring values (up to 80% less norm non-compliances). By incorporating the impact of the strategies on related processes, like the bypass of primary settling tanks, energy consumption could be reduced by almost 25%. Many of the elaborated strategies can be transferred to WWTPs with similar boundary conditions and strict effluent values worldwide.

Copula-based modeling of hydraulic structures using a nonlinear reservoir model

Multivariate flood frequency analysis has been widely used in the design and risk assessment of hydraulic structures. However, analytical solutions are often obtained based on an idealized linear reservoir model in which a linear routing process is assumed, and consequently, the flood risk is likely to be over- or underestimated. The present study proposes a nonlinear reservoir model in which the relationships of reservoir water level with reservoir volume and discharge are assumed to be nonlinear in order to more accurately describe the routing process as it takes into consideration the interactions between hydrological loading and different discharge structures. The structure return period is calculated based on the copula function and compared with that based on the linear reservoir model and the bivariate return period based on the Kendall distribution function. The results show that the structure return period based on the linear model leads to an underestimation of the flood risk under the conditions of high reservoir water level. For the same reservoir, linear and nonlinear reservoir models give quite different reservoir volume-water level and discharge-water level curves; therefore, they differ substantially in the sensitivity to flood events with different combinations of flood peak and volume. We also analyze the effects of the parameters involved in the reservoir volume-water level and discharge-water level relationships on the maximum water level at different return periods in order to better understand the applicability and effectiveness of the proposed method for different hydraulic projects.

Performance Enhancement of Split Air Conditioner During Evaporative Cooling Application

The increase of condenser temperature and pressure in air-conditioning leads to decreased cooling capacity and the increase of power consumption. Evaporative cooling could improve the thermal performance of the system. In this study, the evaporative cooling module was installed before the condenser to reduce the inlet air temperature to the condenser unit. The impact of condenser air temperature on the air conditioning system's overall performance was determined by varying the cooling pad discharge water flowrate of 880, 1040, and 1200 mL/min. The cooling load of 2000 W was employed in this experiment. The obtained results were compared with the air conditioning without an evaporative cooling module. It shows that the coefficient of performance (COP) increases with the increase of discharge water flow rate. The highest COP obtained is 7.09 at the flow rate of 1200 mL/min. The compressor work reduces about 6.57 % as compared with the air conditioner without evaporative cooling application. Besides, the COP increases by 12. 95 % at the highest flow rate.

Steady-State Hydraulic Analysis of High-Rise Building Wastewater Drainage Networks: Modelling Basis

A model is presented which allows steady-state pressure profiles in high-rise wastewater drainage networks to be related to intake air flowrates and discharge water flowrates. This model is developed using data taken from academic literature, and is based on experimental observations which suggest that a vertical annular downflow develops over distance such that the pressure gradient in the wet stack may be expressed as the sum of junction components and developed flow components. The model is used to analyse a simplified ‘medium rise’ primary vented system of height 40 m, hosting two inflow junctions, crossvents and Air Admittance Valves (AAVs). The model illustrates how the air supply configuration affects the airflow rates within the stack and the vents, and how the configuration affects the steady-state hydraulic pressure profile. The model offers the possibility of an alternative approach to the design of high-rise wastewater drainage networks, compared to existing design codes. These codes generally do not explain the role that the air admitted into the network has upon its performance.