Hot Wastewater Research Articles

Thermostable nanofiltration membranes enabling superior hot wastewater purification

Emerging nanofiltration (NF) separation technology for precision ionic/molecular separation at the nanoscale, which has the advantages of energy conservation, excellent separation and a small footprint, is promising for obtaining sustainable water resources via efficient water treatment and recycling. However, traditional NF membranes are restricted to applications at approximately room temperature because of the sharp deterioration in stability induced by the fragility of the nanopore structure at higher temperatures. Herein, we synthesized an unparalleled nanofiltration (NF) membrane with superior thermal stability up to 90 °C and finely tailored nanopores with 0.3–1.1 nm, via de novo carbon skeleton-mediated polymerization (CSMP). Molecular thermodynamics simulations and experiments demonstrated that C–C skeletons can manipulate the stability of the intrinsic structure and intermolecular gap size, contributing to exceptionally thermostable and well-tailored nanopores. The synthesized membrane exhibited excellent long-term water permeance and high rejection of (sub)nanoscale contaminant molecules at high temperatures, which is far superior to the performance of currently available NF membranes.

A Study on Modification of Boiler Chimney against Fouling to Enhance The Efficiency of Boiler

The boilers lose heat through various means, this statement refers to various ways in which heat is released or transferred, such as the emission of hot gases from chimneys, the disposal of hot wastewater, and the transmission of heat from heated surfaces. This study focuses on a chimney originally designed for a 15-ton/hour, 16-bar boiler. The issue with the chimney is that it experiences a high accumulation of carbon particles. In an effort to address the issue, the chimney has been re-engineered to minimize the build-up of scale which impacts the boiler's performance. It is specifically designed for use in boiler chimneys and features a hatch. The goal of this project is to decrease the size of the cross-sectional area of this particular section in order to enhance the flow of flue gases.

A short review of recent studies on wastewater heat recovery systems: Types and applications

Reducing energy consumption has its direct impact on the worldwide environmental status. Smart energy processes must be adopted in order to enhance the reduction capacity of energy usage. In this view, both renewable energy as well as heat recovery strategy has been used in a wide range of engineering applications. With this in mind, hot wastewater is considered as a valuable source of energy that could be recovered. The present paper illustrates an overall review on the waste water heat recovery systems (WWHR). All systems can be classified based on their structural configuration and application. It has been shown that under some conditions a 50% energy could be stored or recovered using a heat recovery system. In addition, all systems are considered as an economic as well as environmental effective methods.

Preliminary Study on Geothermal Direct Utilization: A Case Study of Greenhouse Optimization at Wayang Windu Geothermal Area

West Java Province in Indonesia has a geothermal district, one of the existing power plants is Wayang Windu. Besides the geological factors, the development of geothermal energy is determined by socio-economic. This paper examines the preliminary study of direct geothermal energy utilization in a tea plantation in Malabar, Indonesia. The land that has not been cultivated yet is available in that area, and it is near the Wayang Windu. The greenhouse design for 1 hectare which divided into six bays using a cascade cycle from Wayang Windu power plant. This study select capsicum annuum as a case study regarding the opportunity to produce in Bandung City. The minimum heat supply for the greenhouse is 1.25 MW from the hot wastewater from Wayang Windu. The estimation of the greenhouse will reduce carbon emission by around 84% compare with industrial diesel oil (IDO).

Power generation of thermoelectric generator with plate fins for recovering low-temperature waste heat

Low-temperature waste heat has great potential for renewable power because it accounts for around 60% of total industrial waste heat. This study develops a model of integrating thermoelectric generation, computational fluid dynamics, and plate fins to figure out a low-temperature waste heat recovery system for power generation. The effect of the number of partitions of a thermoelectric module on its performance is examined, and the results show that a single module without a partition can provide accurate predictions. Four different combinations between wastewater and air in the hot and cold channels under three different Reynolds numbers (i.e., Re = 10, 100, and 1,000) on thermoelectric modules’ performance suggest that only combining hot wastewater and cooling water can contribute electricity to a certain extent. By installing fins with a number range of 0–27, it indicates that fin installation can dramatically intensify heat transfer and thermoelectric modules’ performance. The optimal number of fins at Re = 10 and 100 is 21, whereas it is 27 at Re = 1,000. The maximum total output power and mean conversion efficiency are 0.411 W and 0.95%, respectively, with 27 fins at Re = 1,000. These values account for 105.5% and 43.94% improvements when compared to the TEMs without fins. Even though installing fins increases the pressure drop in the channel, its value is much smaller than the generated power (less than1%). The developed method in this study can be used to efficiently and accurately predict the performance of thermoelectric modules, and obtained results have provided practical insights into the design of low-temperature waste heat recovery systems for green power generation.

One-way conformation memory polymers for unidirectional removal of dyes and hot wastewater reuse from textile effluents

Thermoresponsive polymers that adapt their conformation transition from coil to globule in response to temperature change have aroused great interest in the last two decades. However, thermally induced phase separation behavior often involves dynamically reversible switching between two distinct conformations during multiple heating–cooling cycles, which hinders their potential applications in many directional, nonreturn molecule delivery systems. Here, inspired by a nonreturn valve, a new class of thermo-irreversible starch derivatives (TIRS) is presented. As an unprecedented one-way conformation memory polymer, TIRS exhibits usual lower critical solution temperature type fast responses to temperature stimuli, but this phase transition behavior involves ir-reversible switching upon cooling. The extent of hysteresis (reversible, semi-reversible and ir-reversible) between heating and cooling ramps can be fine-tuned by varying the degree of substitution of starch derivatives. The unique conformation-adaptive feature of TIRS makes it a very interesting candidate for the unidirectional removal of dyes and hot wastewater reuse from textile effluents. TIRS shows a maximum dye uptake capacity of 3984 mg/g and excellent decoloration efficiency of 99.6% at optimized flocculation conditions. After flocculation with dyes, the temporary conformation of flocs can be memorized and self-locked due to the unidirectional solubility switching of TIRS from water-soluble flocculants to water-insoluble adsorbents, which avoids unnecessary desorption and re-solubilization of the flocculant. Clarified hot water can be employed as reuse water in new dyeing operations due to low flocculant residues in reclaimed water. This work offers a new approach to design and fabricate check-valve-like materials for self-adaptive, ir-reversible smart delivery systems.

Waste Heat and Wastewater Recovery in Textile Processing Industry: A Case Study of Adopted Practices

Textile wet processes dispose of huge amounts of water and energy in the form of hot wastewater and exhaust gas emissions. A significant amount of water and energy can be conserved by adopting various waste heat and water recovery methods, such as the use of heat exchanger, recycling hot wastewater, steam condensate, and cooling water recovery and reuse. In this study, various waste energy and water conservation methods are summarized to highlight their importance for water and energy conservation. For practical consideration, a detailed assessment of such practiced methods was done in one textile processing industry. The obtained results revealed that a high amount of energy and water could be conserved by adopting various waste heat and water recovery methods, with the advantage of reducing environmental pollution while minimizing the consumption of energy and water.

Experimental investigation and thermal analysis of a double slope long still: study of heat and mass transfer

Water, which is used as a cooling agent in various thermal power-based industries, is utilised for the extraction of heat from numerous equipments. Extracted energy need to be discharged in ambient by using chiller/cooling devices for the recirculation of water. The utilisation of this discharged energy for distillation can enhance the overall efficiency of such industries. Proposed double slope long still (DSLS) can be utilised in enlarge scale in between the discharge and cooling/chiller units, for the utilisation of energy present in the hot wastewater to get distillate. Experimental and numerical evaluations have been carried out and reported in this manuscript. It has been observed that the evaporative heat transfer coefficient gets reduced by 64.39% from the inlet to the exit of DSLS. Whereas the energy fractions viz. evaporative, radiative and convective are reduced and increased by 18.38% and 89.80% & 92.18%, respectively. The theoretical results are in good agreement with the experiments.

Hot water recovery and reuse in textile sector with pilot scale ceramic ultrafiltration/nanofiltration membrane system

This work is being conducted by real wastewater from disperse printing and reactive printing washing baths hot discharges mixing point and it was aimed to be treated and hot water recovery and reuse in the plant was targeted. For this purpose, pilot scale ceramic ultrafiltration/nanofiltration membrane system was used. In first ten cycle, ultrafiltration + nanofiltration membranes and in last four cycles only nanofiltration membrane was used. All samples were subjected to chemical oxygen demand, total hardness, total organic carbon, color and conductivity tests. Flux and temperature were also monitored throughout operations. According to obtained results, for ultrafiltration + nanofiltration cycles overall average removal efficiencies are 89%, 83.5%, 86.4% and 68% for chemical oxygen demand, color, total organic carbon and hardness, respectively. For only nanofiltration cycles, overall average removal efficiencies are 90.1%, 82.2%, 76.8% and 82% for chemical oxygen demand, color, total organic carbon and total hardness, respectively. Besides, treated wastewater was tested whether it is suitable for dyeing processes or not. And according to temperature difference between inlet and outlet streams, it can be said that it is feasible to use ceramic membrane technology for hot wastewater recovery and reuse.

Eksperimentalna evaluacija i teorijska analiza destilatora dugih razmera pokrivenih limovima od GI, Cu i Al

Electrical energy is mostly converted from thermal energy drown from the thermal or nuclear power plant for large scale and Diesel generator (DG) sets are used as a backup device. In these, we mostly used water as a working substance and cooling agent for maintaining the operating temperature of the devices. Experimental and theoretical evaluation of three identical reduced scales long still prototypes covered with the different metallic sheets (viz. GI, Cu, and Al) are reported in this manuscript. Hot wastewater at 70±1 ºC is fed to the distiller unit as a discharge of the thermal unit is ranges between 65 to 75 ºC. The theoretical result obtained from the regression analysis gives good agreement with the result obtained from the experimentation. Long still covered with the Cu sheet material is gives better performance as compared with the others (viz. 55.03 and 34.69% higher than the GI and Al sheet cover). It has been observed that the still covered with the Cu sheet gives better distillate yield as compared with the still covered with the Al or GI sheet material.

Removing fluoride from hot spring wastewater by an electrolysis system with a perforated plate as a diaphragm

A continuous electrolysis system using an electrolysis reactor cell separated into an anode cell and a cathode cell by a perforated plate as a diaphragm was operated in a laboratory to remove fluor...

Potential influence of sewer heat recovery on in-sewer processes.

Heat recovery from combined sewers has a significant potential for practical renewable energy provision as sources of heat demand and sewer pipes are spread across urban areas. Sewers are continuously recharged with relatively hot wastewater, as well as interacting with heat sources from surrounding air and soil. However, the potential effects of modifying sewage temperature on in-sewer processes have received little attention. The deposition of fats, oils and greases (FOGs) and hydrogen sulphide formation are biochemical processes and are thus influenced by temperature. This paper utilises a case study approach to simulate anticipated temperature reductions in a sewer network due to heat recovery. A laboratory investigation into the formation of FOG deposits at temperatures varying between 5 °C and 20 °C provided mixed results, with only a weak temperature influence, highlighting the need for more research to fully understand the influence of the wastewater composition as well as temperature on FOG deposit formation. A separate modelling investigation into the formation of hydrogen sulphide when inflow temperature is varied between 5 °C and 20 °C showed considerable reductions in hydrogen sulphide formation. Hence, heat extraction from sewers could be a promising method for managing some in-sewer processes, combined with traditional methods such as chemical dosing.

Experimental evaluation of a long still with galvanised iron sheet as condensing cover at different basin water flow rate: study of heat and mass transfer

Experimental and theoretical evaluation of a long still for the utilisation of residual heat energy from hot wastewater discharge of thermal power generation-based organisations has been investigated and reported in this paper. The experiment has been carried out to find the variation in productivity with respect to different feed rates viz 100, 150, 200, 250 and 300 LPH at 10 different points. It has been observed that the distiller unit at a feed rate of 250 LPH gives maximum distilled output as compared to the feed rates of 100, 150, 200, and 300 LPH. At 250LPH flow rate, a distill yield of 0.0868 kg/h is recorded which is 34.99, 17.14, 4.52, and 0.01% higher as compared to the 100, 150, 200 and 300 LPH flow rate feed hot waste water, respectively. It has been observed that the long still gives maximum and minimum yield at entrance and exit, respectively.

Evaluation of maintenance chemical cleaning in seawater reverse osmosis pilot plant using hot wastewater from power plant

Evaluation of maintenance chemical cleaning in seawater reverse osmosis pilot plant using hot wastewater from power plant

Performance evaluation of long still for the utilization of industrial hot waste water

Abstract Various industrial equipment is utilizing water as a cooling agent for maintaining their operating temperatures within the stipulated range. The water-cooled equipment produces a large quantity of hot wastewater, which is generally sent to the chiller units for cooling. Proposed reduced scale model of a long single basin, single slope still is an attempted to utilize this waste energy for desalination. Experimental and theoretical evaluation has been carried out by feeding hot water at 70 ± 1℃ at a constant flow rate of 1100 l/h. Dunkle, Kumar & Tiwari and Tsilingiris models have been used for the comparative theoretical analysis of long hot waste water still. The maximum and minimum values of partial pressure have been recorded at the water and glass surfaces are 32492.648 & 10658.271 N/m2 and 19906.001 & 5660.855 N/m2 respectively. At 0.1, 0.3, 0.5, and 1.2 m the partial pressure at the water surface is 63.23, 81.39, 71.77 and 88% higher than the glass surface. Kumar & Tiwari leads Dunkle and Tsilingiris models at 0.1 m by 6.91 and 4.63%, whereas this difference grows to a maximum value of 42.093 and 55.07% at 1.1 m respectively.

A Study on Reduction of Fog Generated from Hot Waste Water Treatment Plant Waste Water at Display Industrial Complex

The hot waste water from the display industrial complex affects the traffic and the surrounding environment due to fog generation in the surrounding area in winter. A simulator was built to predict the occurrence of fog due to temperature changes. Humidity change was measured after setting the temperature and ambient temperature of the hot water. The evaporation rate was compared at the reservoir discharging the hot water. When the temperature was 28oC and the atmospheric temperature was -5oC, the evaporation rate rapidly saturated to 0.9 cm/day or more. It was found that the temperature difference between the water and the atmosphere in winter exceeded the fog generation criterion of 8oC, and the evaporation amount easily changed to fog. The calculated results from the relative humidity using the simulator were in good agreement with the evaporation rate. When the temperature of the hot water is cooled from 28oC to 21oC, it is confirmed that the amount of evaporation can be reduced by 33% that result in decrease of fog generation.

For sustainable development of the whole world by renewable energy

The atmospheric carbon dioxide concentration has been increasing at the rate of about 1.85 ppm/year since 1970, and exceeded 400 ppm corresponding to the level in 3.5 million years ago. No current all living things have the experience to live in such climate. Extrapolation of recent increase in the world primary energy consumption indicates that all reserves of fossil fuels and uranium will be completely exhausted until the middle of this century. In order to avoid the crisis of intolerable global warming and no fuels for combustion we have to establish and spread the technologies to use only renewable energy by which the whole world can keep sustainable development. There are superabundant renewable energy resources on our planet. We have been performing research and development for about 30 years to supply renewable energy to the world in the form of methane by electrolytic hydrogen generation and subsequent formation of methane from carbon dioxide and hydrogen. We created anodes and cathodes for water electrolysis and catalysts for carbon dioxide methanation. We constructed a prototype plant consisting of solar cell, water electrolyzer, carbon dioxide methanation unit, methane combustor with oxygen and piping connecting methane production and combustion units in 1995. We are recommending the construction of local energy supply system. The power generated from renewable energy will be used directly. The surplus electricity must be used for water electrolysis to form hydrogen and oxygen. Hydrogen will be used to form methane by the reaction with carbon dioxide. Methane will be used for regeneration of steady electricity at a natural gas power plant for covering shortage and leveling of intermittent and fluctuating power generated from renewable energy. For combustion of methane at the power plant oxygen formed by the water electrolysis will be used after dilution with carbon dioxide of exhaust gas, so that the it will be composed of only carbon dioxide after removal of water. Thus, carbon dioxide of the exhaust gas will be recycled for methane formation and oxygen dilution. Hot waste water of the power plant will be used in the local area for heating, farming and industries.

PENGARUH PENGARUH BENTUK DAN KONFIGURASI ALUR SEKAT TERHADAP UNJUK KERJA MENARA PENDINGIN (COOLING TOWER)

The cooling tower is mechanical equipment which used to decrease hot waste water. One of the factors that influence the performance is the filling components. This research is aimed to get the effect of buffle’s shape and configuration due to cooling tower performance. The cooling tower performance is described with range, heat transfer rate, and efficiency. The research is done by an experiment using laboratory scale cooling tower. The shape is varied as circle and triangle with 2-3 and 3-2 in a row configuration. The water flow rate is adjusted with 3 valve opening. Water temperature inlet is varied as 50, 60 and 70oC. The measurements are taken for inlet and outlet water and air temperature for 3 times measurements using K-type thermocouples. The result shows that buffle’s shape and configuration have an effect due to cooling tower performance.
 Keywords: cooling tower, performance, buffle’s shape, configuration

Hot wastewater recovery by using ceramic membrane ultrafiltration and its reusability in textile industry

Ceramic membrane filtration is a viable option for recovery of hot discharges due to their high mechanical, chemical and thermal durability. Recovery of hot discharges in textile industry with this method has not been studied in detail previously. In this study, the potential recovery of hot textile wastewater discharges was assessed in situ taking into consideration the amount, pollutant content and costs of the water. Samples were selected from potential recovery points according to wastewater amount, temperature and accessibility and were evaluated using laboratory scale ceramic membrane filtration with four different MWCO (300 kDa, 50 kDa, 15 kDa and 3 kDa) membrane sizes. The pollutant size distribution correlated with removal efficiency of the method and the highest pollutant removal efficiency was achieved with the 3 kDa ceramic membrane. However, the mixed hot wastewater and disperse printing washing baths mix permeate from the 3 kDa membrane had high COD and TOC contents and was not optimal for reuse without additional treatment. The printing washing baths hot discharges mix was the most appropriate option for reuse with 67 ± 12 mg COD/L, 21 ± 4 mg TOC/L and 23 ± 7.7 mg CaCO3/L Total Hardness values which could be reused in dense dyeing and printing baths washing after 3 kDa ceramic membrane ultrafiltration. In order to define the fouling mechanism, resistance-in-series model was used and physically removable resistance was the main contributor to overall fouling.With this method, not only the reuse requirements will be met but also 22% of total water consumption may be reused and thus wastewater, energy and water related expenses may be reduced significantly in textile industry.

Enhancement of integrated solar still using different new absorber configurations: An experimental approach

Solar stills yield only lower amount of fresh distillate, when compared to other conventional based desalination systems. In the present work, in an intention to increase the solar still productivity, a new hybrid solar desalination system was developed by combining an inclined solar still with a single basin solar still and hot water storage tank. This integrated system was fabricated and tested with different geometry of new absorber plate configurations (flat, grooved and fin shaped absorbers) under actual climatic conditions. The different new absorbers used in this experiment, increases the surface area of water available for evaporation inside the inclined still. In this experimental study, the integration of these stills was done to recover the waste heat energy from the un-evaporated output (hot waste water) drained from the inclined still. Based on the experimental analysis, it was observed that for the conventional inclined still, 25.75% productivity increased, when it is coupled with fin shaped absorber and 74.5% productivity increased, when it is integrated with basin still. The overall productivity (distillate output) in the integrated still with fin shaped absorber configuration was 5210ml/day and the efficiency of the integrated desalination system with hot water thermal storage was 46.9%.