Hasil untuk "Sewage collection and disposal systems. Sewerage"

M. Sakala, Danny Chisanga Musenge

The rapid population growth in Lusaka has brought adverse effects on water supply and sewerage treatment facilities in the district. Consequently, authorities in Lusaka have allowed use of pit latrines, septic tanks, boreholes and wells in the same area in some townships. Mtendere east located about 20.9km from town centre is one of such areas. Lusaka city is built on marble which is cut by a network of fissures that open hollows or filled with soil. This reduces the attenuation of pollutants that would occur through natural filtration. A study on groundwater that was conducted in 2010 in selected areas of Lusaka showed high levels of contamination with bacteria. The general objective of this study was to assess the effects of pit latrines on underground water quality in wells in Mtendere East. Specific objectives were to determine the effect of distance between pit latrines and wells on ground water quality in Mtendere east, to assess the effect of siting water wells and pit latrines in relation to the direction of ground water flow on the ground water quality, to come up with a sampling frequency, to analyse Total and Faecal coliforms, PH, Turbidity, Conductivity, Nitrates and Total Phosphates levels in the water samples collected from the wells in comparison to WHO standards. The study site was purposively selected because all households in the compound used Pit latrines and wells for human waste disposal and drinking water supply respectively. The study population of the area is over 50 000 from which a sample size of 40 houses was raised (Rao soft sample size calculator, at 95% level of confidentiality and 5% level of error). Following oral consent of the respondents, representative members of 10 houses in each of the 4 hand dug well locations were engaged which resulted into a total number of 40 respondents; this was reached by interviewing every 10th household in the area. In each of the households and the site that was visited, water sample from the local well, depth of the wells and that of a pit latrine was taken as well as the distance between the well and the corresponding pit latrines. The majority of water samples collected from households in the first, second and third tests in Mtendere East were found to be contaminated by faecal coliforms, while in the second and third tests the control point was not contaminated by faecal and total coliforms. The study revealed that the direction of groundwater flow had an association with water quality (total coliform and faecal coliform) at 5% significance level with p-values equal to 0.001 and less than 0.001 respectively. Distance from Pit latrine to Wells was insignificant in the quality of water. In conclusion, siting wells and pit latrine systems in the same area was not suitable for Mtendere East compound and Lusaka at large because safety of groundwater cannot be guaranteed. Partners in water resource management such as ZEMA, Department of Water Affairs, Geological Department and Lusaka City Council should, therefore, work together each time projects that involve groundwater development and onsite wastewater treatment are to be implemented. LWSC to quickly finish the water and sanitation project currently under construction so as to provide piped water and sewage services to Mtendere East.

Meshbaul Hassan Chowdhury, S. Amin, Maeesha Mobashwera et al.

One thing that has raised concerns for people across the globe is the rising threats to the environment and the fast-approaching calamity of global warming and climate change. Companies play a key role in contributing to the damage done to the environment on a daily basis. Hence, they need to take sustainability into consideration to reduce their harmful impact on the environment. This study aims to understand the implications of incorporating reverse logistics and waste management practices and the challenges faced by establishments in the urban tourism industry of Bangladesh. Cox's Bazar is home to the largest sea beach in the world and is one of the most visited places by both domestic and foreign tourists in Bangladesh. However, the lack of Sewerage Treatment Plants (STPs) and a poor waste management system has been a major hurdle. This study explored the current condition of waste management practices and the challenges establishments may face if reverse logistics and proper waste management practices are implemented. Through a focused group discussion with key stakeholders, the study found that most establishments still need a sewage treatment plant and, thus, are mishandling wastes, leading to several complications for both the tourists and the local residents. In most cases, recyclable waste is not separated and, therefore, is not being recycled. Mismanagement of waste is also posing a threat to marine life while also contributing to environmental pollution. Irregular waste collection, lack of STPs, lack of segregation of the different types of waste, and many other unsafe practices contribute to several adverse environmental and social outcomes. Despite the lack of proper practices and systems in place at present, the urban tourism industry of Bangladesh is gradually moving towards a greener system with a vision for a central STP system in collaboration with the government. Moreover, some establishments in the industry are engaging in collaborative cleaning and waste prevention practices.

Mohammad Javad Omrani, Hamed Farzaneh, Amin Behzadmehr

In recent years, water stress has become a global crisis due to climate and demographic changes and lifestyle changes. Freshwater production from the sea using various processes is known as the most important solution to deal with this crisis. Among these processes, the humidification-dehumidification process has been considered by the scientific community as a flexible and low-cost method. The present work has investigated the performance of vortex-humidification-dehumidification water desalination cycle. The existing system is a dehumidifier-dehumidifier type, in which a vortex tube has been added. According to the structure of the vortex tube, its hot air outlet has been used to increase the possibility of moisture absorption in the humidifier and its cold air outlet has been used to increase the amount of condensed water in the humidifier. According to the second law of thermodynamics, the performance of the cycle has been studied. In the analysis of multi-flow cycles with heat and mass transfer, the commercial software EES has been used to solve the equations. The fresh water output for specific conditions (sea level, air temperature 35 degrees Celsius and relative humidity 30 percent) is equal to 7.85 kg/h and the research results show that the Gained-Output-Ratio is equal to 1.189. It is shown that the use of the vortex tube and the consequent increase in air temperature at the inlet of the humidifier and the use of the second dehumidifier in the cycle increase the production of fresh water.

Afifudin, M. Widyastuti

Sanitation visualizes the environment’s health status, comprising housing, sewage disposal, and clean water provision. In general, sewerage can have on-site and offsite sanitation facilities. The research was conducted to characterize the sanitation system for sewage disposal, determine the water quality from biological parameters, and enumerate coliform bacteria in groundwater for every sanitation system observed in Wonosari District, Gunungkidul Regency, Indonesia. These sets of information can help detect groundwater contamination by coliform that reflects the sanitary characteristics of the sewage disposal to be further considered in sanitation management and treatment policies. The research used purposive sampling, field surveys, interviews with a questionnaire, laboratory analyses, and a descriptive-comparative design. The results showed that the sanitation system for sewage disposal at the study site consisted of individual septic tanks and wastewater treatment plants (WWTPs). In terms of quality, the coliform counts exceeded the existing standards, with the highest presence found in groundwater downstream of improperly maintained WWTPs and substandard septic tanks close to other sources of pollutants.

V. A. Bober, R. V. Chupin, D. V. Skibo et al.

Improving the reliability of sewer systems involves implementing measures and facilities to prevent the discharge of untreated sewage onto the ground or surface. These measures include the redundancy of both pressurized and non-pressurized pipelines within the network, as well as the use of their accumulating capacity and emergency wastewater tanks. The accumulating capacity of a gravityflow sewer system was examined in this work. An algorithm for calculating the accumulating capacity of existing sewer systems was proposed. Additionally, the study explored methods to enhance accumulating capacity by replacing smaller diameter manifolds with larger ones and implementing blocking devices (back-flow barriers) in control wells to prevent wastewater from reaching the surface and to transfer wastewater flow from gravity-flow to pressurized mode. In order to investigate the accumulating capacity of existing gravity-flow collectors in the sewerage handling area to maintain operations during a 6-hour pump station shutdown resulting from an accident, the sewerage pumping station-18 (SPS-18) in Irkutsk was taken as an example. On the basis of the performed calculations, it is suggested that five control wells be equipped with blocking devices in order to increase the accumulating capacity of the gravity-flow network to the required levels. The article offers a methodology for calculating and developing the required accumulating capacity of the designed, existing, and reconstructed sewer systems. The research findings can be useful for updating the development plan for the water supply and wastewater disposal systems of the city.

S. Manzhina

Purpose: to determine the key incentives for developing irrigation in the regions of the country with a clear shortage of water resources through the use of domestic wastewater discharged from municipal sewage treatment plants. Discussion. The use of domestic wastewater for irrigation has been practiced by ancient civilizations. In modern realities, as earlier, irrigation with domestic wastewater and water of varying degrees of purification is most widely practiced by farmers and other consumers having land near municipal sewerage systems, which makes it easier to transport irrigation water and reduce financial costs for their post-treatment. In order to promote social and environmental policies on efficient wastewater disposal, various motivating mechanisms are used. The main positions that should be taken into account in the case of planning wastewater irrigation are highlighted. The data on using wastewater for irrigation in foreign practice are presented, the motivating mechanisms used to stimulate such usage and the current Russian and foreign standards used to assess the quality of treated wastewater are highlighted. In Russia, no additional incentive mechanisms for wastewater post-treatment of in irrigated fields are used. The main incentive is the ability to avoid payments and fines for discharge of wastewater of inadequate quality. Such an incentive works only for enterprises that carry out the removal and treatment of domestic wastewater, and there are no incentives for Russian farmers to develop wastewater for irrigation. Conclusions. Of particular importance are the financial indicators and economic benefits for the parties involved in the implementation of the process of irrigating crops with treated wastewater. If we focus on the international experience of motivating incentives, it is of particular interest to vary the payment for irrigation water depending on its quality and consumption amount.

Farimah Bakhshizadeh, Mohammadreza Jelokhani-Niaraki, Somaye Mahmoudi

Wastewater network as one of the most important infrastructure facilities can play an important role in achieving sustainable development by improving public health and environmental protection by preventing pollution of surface and groundwater resources. One of the most common incidents that occurs significantly in this network is blockage of the sewer pipes. Recognizing the factors influencing the occurrence of network blockage has a significant impact on accurately predicting what may happen to the network in the future. In the present study, GIS tools and artificial neural network were used to predict and mapping the potential for blockage in the sewer network. Important factors in the occurrence of blockage including, land use, siphon diameter, siphon depth, depth, materials and age of the pipe were used in neural network analysis. From input data of 70%, 15% and 15%, respectively, were used for training, validation and model testing. The results of the simulation using a neural network with a Performance Indicator of R2=0.9 showed a high fitness between the predicted and observed locations of the blockage. Also, in the blockage potential map, areas with high population density, worn texture and unauthorized constructions (due to the installation of unauthorized branches) were observed blockage potential.

Justyna Rogowska, Agnieszka Zimmermann, A. Muszyńska et al.

Pharmaceutical consumption continues to grow constantly. Unused/expired pharmaceuticals are disposed of to the municipal sewage system or waste disposal. Consequently, many countries have implemented a system of collecting pharmaceutical waste, with pharmacies playing an important role. It is important to educate consumers on rational consumption and the appropriate disposal of unused/expired pharmaceuticals and to identify the level of public awareness. Two studies were conducted in Poland to estimate the problem of collection and disposal of expired/unused pharmaceuticals. The purpose of the Survey I was to identify the scale of pharmaceutical consumption and the way pharmaceuticals are disposed of by various social groups. The Survey II was aimed to identify patients’ attitudes regarding expired/unused pharmaceuticals at home. Of the respondents who participated in in Survey I, almost 74% indicated that analgesics were among the over-the-counter drugs they purchased. Group of pharmaceuticals 65% of the respondents purchased were medicines for treating flu symptoms. Almost 68% of the respondents said they usually disposed of expired pharmaceuticals in their household waste or by flushing them down the toilet. In Survey II more than 35% reported that they disposed of pharmaceuticals in the same ways. Of all respondents, ~30% returned their expired pharmaceuticals to pharmacies. Most respondents (over 65%) who participated Survey I indicated that they were aware that pharmaceutical waste can be returned to pharmacies. It should be noted that local governments are currently not obliged by law to work with or compensate pharmacies in the collection and proper disposal of unused pharmaceuticals.

Zeinab Hadadian, Mostafa Ansari, Ali Haghighi et al.

Today, water desalination methods are of great importance in solving the freshwater crisis in the world, so that in recent years, the world's water desalination capacity has increased dramatically. Among them, the reverse osmosis membrane technology has been the most popular and the most commonly used. There are problems such as high energy consumption, high operating costs, and fouling in this method. The objective of this paper was to use reverse and forward osmosis membrane methods simultaneously in a hybrid reverse-forward osmosis setting, which enabled us to take advantage of the benefits of forward osmosis such as not being dependent on high hydraulic pressure, lower cost and less membrane fouling compared to reverse osmosis. Another objective of the study was to evaluate the permeate water production efficiency of desalination with this hybrid method. It is expected that using the hybrid method will reduce the required pressure for conducting reverse osmosis process to achieve a specified permeate flux, because it reduces cost and energy. An HRFO laboratory pilot with a capacity of 50 m3/day was designed and set up in the Hydraulic Lab of Shahid Chamran University of Ahvaz for running hybrid experiments. The design of the pilot was such that it could operate in both reverse osmosis and HRFO. HRFO experiments were carried out at pressures of 4.5 to 10.5 bar for Ahvaz urban water as feed solution, as well as NaCl as draw solution with a concentration of 2000 to 10000 mg/L via the experimental HRFO plant. It was found that adding the forward osmosis to reverse osmosis at the best situation (lowest pressure and highest concentration of draw solution) can increase the permeate water production efficiency of desalination by 55.12%. The best hybridization degree of these two methods was determined to be 64.5% for reverse osmosis and 35.5% for forward osmosis.

Seyed Mohammad Javad Hoseiny Shams Abadi, Maryam Hasani Zonoozi

Nitrogen compounds such as ammonium and nitrate are among the most common pollutants in wastewater and water resources. Removal of these substances is essential for reducing their adverse environmental and health effects. One of the biological methods for eliminating nitrogen is the simultaneous nitrification and denitrification process (SND) which, due to simplicity and cost effectiveness has attracted much interest. The SND can be performed by using bacterial attachment growth. The COD/N ratio is one of the effective parameters on the SND process. It can influence the process performance by changing the biofilm mass and the bacterial population. For this reason, the purpose of this study was to investigate the effect of COD/N ratio on simultaneous nitrification and denitrification in aerobic moving-bed sequencing batch reactor (MBSBR). For this purpose, an aerobic MBSBR reactor was operated in two phases. The selected values for COD/N in phases 1 and 2 were 10 and 20, respectively. According to the results, doubling of COD/N significantly increased the biofilm mass from 15 mg/media to 25 mg/media and increased the effluent COD from 22 mg/L to 192 mg/L as well, for phases 1 and 2, respectively. However, it had trivial effect on the concentration of suspended solids. The ammonium concentration in effluent of phase 2 was around 30 mg N/L which was about 33% more than that of phase 1 (10 mg N/L). This indicates a decrease in the rate of ammonium oxidation in phase 2 which most probably was attributed to increase of the population of heterotrophic bacteria and inhibition of the growth of autotrophs as a result of the higher abundance of organic matter in this phase compared with phase 1. In phase 2, in spite of increasing biofilm mass and part of the organic matter remaining until the end of the cycle (the factors that make the conditions more desirable for denitrification), denitrification decreased and from about 39% in phase 1 reached 12 % in this phase. The reason for this observation was the lack of proper nitrification and low concentration of nitrate in phase 2. Therefore, it can be said that by increasing COD/N ratio, the nitrate concentration, or in the other words the nitrification process, has become the controlling factor of the denitrification process. In general, in phase 1 (COD/N of 10) simultaneous nitrification and denitrification took place much better so that more than three-fold nitrogen removal efficiency was achieved compared with phase 2 (COD/N of 20).

M. Ortner, W. Müller, I. Schneider et al.

Mohammad Attari, Mahmoud Faghfour Maghrebi

Nowadays water loss has been turned into a global concern and on the other hand the demand for water is increasing. This problem has made the demand management and consumption pattern reform necessary. One of the most important methods for managing water consumption is to decrease the water loss. In this study by using neural networks, a new method is presented to specify the location and quantity of leakages in water distribution networks.  In this method, by producing the training data and applying it to neural network, the network is able to determine approximate location and quantity of nodal leakage with receiving the nodal pressure. Production of training data is carried out by applying assumed leakage to specific nodes in the network and calculating the new nodal pressures. The results show that by minimum use of hydraulic data taken from pressures, not only this method can determine the location of nodal leakages, but also it can specify the amount of leakage on each node with reasonable accuracy.

V. David, S. Hossain

Ali Reza Rahmani, samira Amini

In this research, oak sawdust, in both modified and unmodified forms, was used as an economical and low-cost material for the removal of arsenic from aqueous solutions. For this purpose, arsenic synthetic samples were prepared using NaAsO2 in distilled water and the effects of pH, adsorbent dosage, contact time, and initial As(V) concentration were investigated on As(V) adsorption using the adsorbents prepared. The results showed that modified sawdust achieved the highest efficiency (>91%) over a contact time of 60 min and at pH 7 when the adsorbent dosage was 4gr/L and the initial As(V) concentration was 150 µg/L. The data from both adsorbents fitted well to the Langmuir isotherm. Under optimum conditions (an initial As(V) concentration of 150 µg/L and optimal absorption pH, contact time, and adsorbent dosage), maximum As(V) removal efficiencies were 93.85% and 91.034% with the modified  and unmodified sawdust adsorbents, respectively. Given the availability and low cost of the adsorbent used and the high removal efficiency obtained at  lower adsorbent dosages and contact times, the modified oak sawdust may be recommended as an effective adsorbent for the removal of arsenic (v) from aqueous solutions, especially since it requires no need for pH modification.

Fatemeh Nooralivand, Ahmad Farrokhian Firouzi, Mostafa Chorom et al.

The present study was conducted to evaluate the feasibility of zero-valent iron nanoparticles (ZVIN) for the removal of nitrate from aqueous solutions. For this purpose, bare zero-valent iron nanoparticles (bare-ZVIN) and CMC-ZVIN were synthesized using the borohydride reduction method and their morphological characteristics were examined via scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier Transmission Infrared Spectroscopy (FTIR). The effects of pH of the aqueous solution, initial nitrate concentration, ZVIN concentration, and contact time on nitrate reduction were investigated as operational parameters and the kinetics of nitrate reduction was studied in batch experiments. The results showed that 93.65% of nitrate was removed by stabilized nanoparticles at pH=6 while non-stabilized nanoparticles at pH=2 were able to remove 85.55% of the nitrate.Furthermore, nitrate reduction was enhanced by increasing ZVIN concentration and contact time while it was decreased as a result of increasing initial nitrate concentration. The major product of nitrate reduction at an acidic pH was found to be ammonium; at an alkaline pH, however, nitrate was converted to nitrogen and nitrite production dropped to less than 2%. Kinetic analysis demonstrated that denitrification of nitrate by the nanoparticles fitted well with first-order and second-order reaction models. The results also demonstrated that the stabilized ZVI nanoparticles were more effective than bare-ZVIN for nitrate reduction in aqueous solutions.

sayed javad Hashemi, Alireza Riahi Bakhtiari, Razie Lak

This study was conducted to determine the origin and distribution of the lead, copper, zinc, nickel, chromium, and vanadium metals in the surface sediments of the southwestern coasts of the Caspian Sea. Surface sediment samples were collected from the three transects of Kapourchal, Bandar-Anzali, and Kiashahr at three different depths of 10, 20, and 50 m. Metal concentrations were determined by ICP-OES. The metals in these areas were identified to originate from such natural sources as rock weathering and soil erosion transported by rivers into the sea. The mean total concentrations of the metals along the three transects showed significant increases with increasing distance from the shore, which might be due to the transportation of sediments as a result of increasing slope along the sampling transects. The same trend was observed in the samples taken from the coastal areas along Bandar-Anzali, which was could be due to the wetlands in the region and the multitude of rivers flowing into this wetland which eventually carried the sediments into the sea. Results revealed that the total metal concentrations in the region were below the SQGs and NOAA standards. Finally, risk assessment code did not show any serious risks, but indicated only a low risk due to lead and copper levels.

Arghavan Mirahsani, Alireza Badiei, Afsaneh Shahbazi et al.

SBA-15 nanoporous silica was prepared and functionalized with propylamine groups via post-synthesis grafting to develop efficient adsorbents of dyes in wastewater. The materials thus prepared were then characterized by XRD, N2 adsorption-desorption, and FTIR. Adsorption of a cationic dye, malachite green, on functionalized SBA-15 was investigated under various conditions of pH (5, 6, and 7), temperature (10, 20, and 30 °C), adsorbent dosage (0.1, 0.3, and 0.5 g/L), and dye concentration (50, 100, 150, 200, 250, 300 mg/L). Maximum equilibrium adsorption capacity to achieve maximum removal percentage (R%=100%) in optimum conditions (dye concentration=100 mg/L, pH=7, adsorbent dosage= 0.3 g/L) was estimated at 333 mg/g. The Taguchi method was used to optimize the adsorption performances of the materials , and then the isotherm, kinetic, and thermodynamic properties were analyzed under the optimum conditions. The results showed that the overall process was fast and its kinetics was well-fitted by pseudo-second-order kinetic model. The experimental data agreed well with Freundlich model. Therefore, the maximum amount of multilayer dye adsorbed was estimated as 500 mg/g. Based on the results obtained, this process may be regarded as an endothermic one with a negative ∆G, which shows the process is also spontaneous. Finally, the results indicate that the silica‐based nanoporous organic–inorganic hybrid material can be a promising sorbent for the removal of malachite green from aquatic solutions

akbar eslami, ahmad reza yazdanbakhsh, hiua daraei et al.

In this study, graphene oxide was used as a nanostructured adsorbent with properties supposedly better than other common adsorbents to remove 4-chlorophenol from aqueous solutions. For this purpose, graphene oxide was initially synthesized using the Hummer's method and x-ray diffraction and scanning electron microscopy were employed to identify its morphology and structure. The variables involved in the absorption process (including 4-chlorophenol initial concentration, adsorbent dosage, and pH) were investigated based on the one-factor-at-a-time method. Eventually, the data were confirmed against the Langmuir and Freundlich isotherms. It was found that the adsorption process reached equilibrium in 20 minutes. A dosage of 0.4 g/L graphene oxide at pH=8 brought about 90% removal of 10 mg/L 4-chlorophenol within 5 minutes. The adsorption isotherm was described well by the Langmuir isotherm model and the values for R2 and RL were recorded as 0.99 for and 0.34, respectively. Being a low cost and highly efficient process, the adsorption process using graphene oxide adsorbent may be recommended for the reduction and elimination of pollutants in the environment, especially those in aqueous solutions.

Rupal Budhbhatti, C. Dasgupta

R. Yadav