Water Recirculation Research Articles

Solid fuel production from co-hydrothermal carbonization of polyvinyl chloride and corncob: Higher dechlorination efficiency and process water recycling

The hydrothermal carbonization (HTC) of polyvinyl chloride (PVC) and wet herbal agricultural wastes for solid fuel production remains bleak economics and sustainability because of high chloride residual, wastewater burden and low production capacity. In this study, the HTC dechlorination was investigated using the first-order reaction kinetic analysis. We found that the co-hydrothermal carbonization (co-HTC) of PVC and the typical biomass (corncob) achieved a staggering drop of dechlorination activation energy from 189.95 kJ/mol to 110.04 kJ/mol. The co-HTC process achieved rapid dechlorination and carbonization due to synergistic effect, to suppress the chlorine content in bituminous-coal-like hydrochar less than 0.05 %. The process wastewater (process water) from co-HTC was recycled four times to evaluate the reusability and chemical evolution. The organics in co-HTC environment enhanced the carbonization which was confirmed by the improved heating value (30.06 to 32.42 MJ·kg−1), hydrochar yield (33.33 % to 36.47 %) and energy recovery efficiency (57.73 % to 68.13 %). The Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) evidenced the process water recirculation maintained high chloride removal. Moreover, the possible formation pathways of two kinds of hydrochars were discussed through the chemical composition of the aqueous phase and the characteristic structures of hydrochar. The co-HTC and process water recycling strategies provide a more promising prospect to convert PVC and biomass wastes into solid fuels.

Application of Biofloc Technology in Indonesian Eel Anguilla bicolor bicolor Fish Culture: Water Quality Profile

Nowadays biofloc technology which utilizes organic matter decomposition activity of heterotrophic bacteria through C/N ratio setting has been widely applied in aquaculture but has never been applied in eel farming. Water quality is a crucial factor in eel aquaculture, one of the prestigious fish commodities. Therefore, this study was conducted to determine the feasibility of biofloc technology to be applied in eel fish culture. The study was conducted using two different pond systems, i.e with and without a water recirculation system. Air in both systems was injected into the water to reach 7-8 mg/L of dissolved oxygen. Molasses and activated charcoal as a carbon source were added so as to achieve a C/N ratio of 20:1. Water quality and microbiology parameters were monitored weekly. The results showed that both biofloc systems were able to maintain water quality very well up to the eleventh week without water replacement, which was characterized by low content of total organic nitrogen and toxic compounds nitrite. Therefore the biofloc technology is suitable to be applied in eel aquaculture.

A model based investigation of evaporative cooling for polymer electrolyte fuel cells – System level analysis

Evaporative cooling is a promising concept to reduce the fuel cell system volume and mass significantly. This paper investigates the interactions between the fuel cell stack and the balance of plant in an evaporatively cooled polymer electrolyte fuel cell system (PEFCS). For this, a zero-dimensional PEFCS model, comprising the fuel cell stack, air compressor, charge air cooler, humidifier, hydrogen recirculation blower, condensing radiator and water separator has been developed and analyzed. Two evaporative cooling system architectures are compared to conventional, liquid cooling. Optimal operating conditions are determined by a numerical optimization of the net system power output. Main results show that evaporative cooling works on the system level over a wide range of operating conditions. The optimum system power and highest efficiencies are achieved at high temperatures (80–90 °C), low pressure (125–150 kPa) and a corresponding cathode stoichiometry between 1.5 and 3, allowing for a closed water loop at the same time. The air compressor shows an increased power demand, compared to conventional cooling and the exhaust gas condenser is identified as the one critical component for evaporative cooling. Its performance is key to an efficient operation and closed water loop at all ambient conditions.

Icreasing the efficiency of district heating supply systems by local heat distribution station modernation

The PURPOSE of the study is to improve the efficiency of district heating systems. To achieve this purpose, the following tasks must be completed. To consider the problems of functioning of an open heat supply system functioning. Perform an analysis of technical solutions for the modernization of local heat distribution and metering station are presented. To develop a technological scheme of local heat distribution station with a hot-water supply system. To determine the main technical, economic and investment indicators of the developed technical solution.MATERIALS AND METHODS. Measurements were made using the local heat metering station. When solving the set tasks, a methodology for assessing efficiency was applied with the calculation of capital and operating costs, including the calculation of the payback period.RESULTS. A new scheme for regulating of hot water supply system recirculation with open connection of consumers to a centralized source is proposed. The results of the implementation of the developed technical solution of local heat distribution and metering station for apartment buildings in Yoshkar-Ola city are presented. An experimental study of the effect of a joint additional installation of a pump and a control valve on the hot water supply system recirculation line before the mixing unit for hot water recirculation with return pipe and before the direct-acting temperature controller was the first to do. As a result, the consumption of district water was reduced by 36 - 39%, the temperature in the return pipeline was reduced by 13.5%; the enthalpy of the hot water was reduced from 0.168 to 0.145 Gcal/m3, the required circulation in all risers of the hot water supply system was ensured.CONCLUSION. The use of the developed technical solution for the modernization of local heat distribution and metering station increases the efficiency of district heating supply systems. Calculations made on the basis of the readings of automatic custody heat transfer meter showed that the payback period for the technical solution is 40 days. The proposed solution is recommended for use in local heat distribution station of open heat supply system in order to reduce water rate, lower the temperature in the return pipeline and reduce heat losses, improve circulation in all riser pipes of the hot water system.

Enhancement of power generation efficiency of PV system using mirror reflector

The global energy demand is increasing rapidly; carbon emissions have increased proportionately in the environment. Thus, there exists a need to augment existing power production capacity without much increase in carbon emissions. A PV system with a reflector mirror has been designed to increase power generation efficiency. The present study is carried out at NIT Kurukshetra (Lat. 29.940N Long. 76.820E); a water recirculation system has also been designed to regulate increased PV surface temperature caused by increased irradiation. The study includes performing tests in October and November 2021 with different reflector angles and comparing these experiments with a reference system under the same climatic conditions. The existence of a mirror reflector and the controlled PV surface temperature jointly enhance the power generation efficiency of the PV system. The average power generation efficiency increase with the use of a bottom reflector and intermittent cooling was 9%-13.5% for different reflector angles. An increase in average electrical efficiency of 8.87% was recorded. The economic analysis of the modified system has also been made.

Submarine groundwater discharge and associated nutrient influx in surroundings of the estuary region at Gulf of Mannar coast, Indian Ocean

The influx of fresh groundwater and re-circulated sea water into coastal ecosystem occurs through the submarine groundwater discharge (SGD). Measurement of salinity, radium tracers (224Ra, and 226Ra isotopes) and nutrients in estuarine water, coastal surface water and groundwater during December 2019 estimated the SGD and associated nutrient fluxes near the Karameniyar estuary (Gulf of Mannar) and surroundings of the Manapad region at southern part of Tamil Nadu state in India. The presence of excessive radium tracers revealed that the SGD was contributing to Ra desorption from the sediments and enrichment in the coastal waters. We estimated SGD of approximately 0.03–0.59 m3 m−2 d−1 for the Manapad region and relatively more homogeneous but comparatively less values in the Karameniyar estuary (0.03–0.34 m3 m−2 d−1). Higher average values of dissolved inorganic nitrogen (DIN; 43.62 μmol L−1) and soluble reactive phosphate (SRP; 1.848 μmol L−1) suggested greater influence of SGD on the overall coastal water nutrient budget. This study also indicated simultaneous occurrence of fresh and saline SGD in this region.

Joint recovery of graphite and lithium metal oxides from spent lithium-ion batteries using froth flotation and investigation on process water re-use

Spent lithium-ion batteries (LIBs) contain critical raw materials that need to be recovered and recirculated into the battery supply chain. This work proposes the joint recovery of graphite and lithium metal oxides (LMOs) from pyrolyzed black mass of spent LIBs using froth flotation. Since flotation is a water-intensive process, the quality of the aqueous phase directly impacts its performance. In pursuit of an improved water-management strategy, the effect of process water recirculation on black mass flotation is also investigated. The fine fraction (<90 µm) of the black mass from pyrolyzed and crushed spent LIBs was used. After flotation, 85% of the graphite in the overflow product and 80% of the LMOs in the underflow product were recovered. After flotation with 8 wt% solids, the process water contained about 1,000 mg/L Li and accumulated up to 2,600 mg/L Li after three cycles. The flotation with process water showed no significant impact on the recovery and grade of flotation products, suggesting the feasibility of water recirculation in black mass flotation.

Thermodynamic Analysis of Air-Cycle Refrigeration Systems with Expansion Work Recovery for Compartment Air Conditioning

As a requirement for sustainable development, air-cycle refrigeration has received wide attention as a candidate for environmentally friendly air conditioning technology. In this study, the thermodynamic performance of air refrigeration cycles is investigated in compartment air conditioning. The effects of compressor efficiency, expander efficiency, ambient humidity, all-fresh-air supply and ambient pressure on the cycle performance are presented. The effects of compressor arrangement in the high-pressure cycle and the low-pressure cycle are compared. An open-loop high-pressure cycle has a larger COP than that of an open-loop low-pressure cycle but requires larger heat exchange. The performance of air refrigeration cycles with full fresh air is studied, and the influence of fresh air is discussed. Schemes for condensed water recirculation with wet compression are proposed, which can improve the COPs of open-loop low-pressure cycles by 44.7%, 48.8% and 48.4%. In the air conditioning of plateau trains, open-loop high-pressure cycles have slightly lower COPs, but they can supply air with elevated pressure and oxygen concentration.

Nilo tilapia (Oreochromis niloticus) performance in different population densities

The objectives of this study were to evaluate the zootechnical indexes (standard length, body width and weight) of Nile tilapia fingerlings (Oreochromis niloticus), of the Aquabel Premium strain, at different stocking densities T1 (250 fish/m3), T2 (500 fish/m3); T3 and T4 (1000 fish/m3) from day zero to 14 and, after, stocking with T3 (250 fish/m3) and T4 with (500 fish/m3) all using artificial aeration. The use of high stocking densities in tilapia culture is a possibility. In intensive systems, the objective is to maximize the use of water, increase productivity and profitability. However, high density is a factor that can be harmful because as it can cause biochemical and physiological alterations in animals. The changes are reflect in the behavior, aggressiveness is evident there is competition for food and territory, this eventually leads to decreased performance and weight loss, the high rates of nitrogenous excreta in the environment cause a decrease water quality. All these associated factors directly affect the growth potential and the welfare of the animals, reflecting in economic losses. While overcrowding triggers high mortality rates, low stocking rates bring economic losses. The experiment was carried out at the São Paulo Agribusiness Technology Agency, located in the city of Presidente Prudente/SP, and had as experimental design different population densities (T1, T2, T3, T4), with two repetitions each treatment. The tilapias were randomly distributed in 08 tanks, with artificial aeration and water recirculation, with unit volume of 250 liters. Oxygen and temperature were measured daily, the hydrogen potential was cheked weekly, and the filters were cleaned 03 times a week. All fingerlings were fed the same commercial feed containing 32% protein, offered until satiation (ad libitum). To evaluate the development of the animals, biometrics were performed at the beginning of the experiment, at 14 and 30 days. According to the results for body weight, there was a statistically significant difference for treatment 1 (T1), which was superior to the other treatments (T2, T3 and T4) at 14 and 30 days of the experiment.

Cascading Crypthecodinium cohnii Biorefinery: Global Warming Potential and Techno-Economic Assessment

Prior to the commissioning of a new industrial biorefinery it is deemed necessary to evaluate if the new project will be beneficial or detrimental to climate change, one of the main drivers for the sustainable development goals (SDG) of the United Nations. In particular, how SDG 7, Clean and Efficient Energy, SDG 3, Good Health and Well Being, SDG 9, Industry Innovation and Infrastructure, and SDG 12, Responsible Production and Consumption, would engage in a new biorefinery design, beneficial to climate change, i.e., fostering SDG 13, Climate Action. This study uses life cycle assessment methodology (LCA) to delve in detail into the Global Warming Impact category, project scenario GHG savings, using a conventional and a dynamic emission flux approach until 2060 (30-year lifetime). Water, heat and electricity circularity are in place by using a water recirculation process and a combined heat and power unit (CHP). A new historical approach to derive low and higher-end commodity prices (chemicals, electricity, heat, jet/maritime fuel, DHA, N-fertilizer) is used for the calculation of the economic indicators: Return of investment (ROI) and inflation-adjusted return (IAR), based upon the consumer price index (CPI). Main conclusions are: supercritical fluid extraction is the hotspot of energy consumption; C. cohnii bio-oil without DHA has higher sulfur concentration than crude oil based jet fuel requiring desulfurization, however the sulfur levels are compatible with maritime fuels; starting its operation in 2030, by 2100 an overall GHG savings of 73% (conventional LCA approach) or 85% (dynamic LCA approach) is projected; economic feasibility for oil productivity and content of 0.14 g/L/h and 27% (w/w) oil content, respectively (of which 31% is DHA), occurs for DHA-cost 100 times higher than reference fish oil based DHA; however future genetic engineering achieving 0.4 g/L/h and 70% (w/w) oil content (of which 31% is DHA), reduces the threshold to 20 times higher cost than reference fish oil based DHA; N-fertilizer, district heating and jet fuel may have similar values then their fossil counterparts.

Effect of water recirculation rate and initial stocking densities on competent larvae and survival of the Pacific oyster Crassostrea gigas in a recirculation aquaculture system

Effect of water recirculation rate and initial stocking densities on competent larvae and survival of the Pacific oyster Crassostrea gigas in a recirculation aquaculture system

PERFORMANCE OF A CONTINUOUS SOLAR WATER DISINFECTION SYSTEM IN ISIOLO COUNTY, KENYA

A continuous solar water disinfection system was designed, installed and tested in Isiolo town, Kenya. The system consisted of two flat plate solar collectors each having 2.34 m2 gross area and photovoltaic pumping system. International Organization for Standardization (ISO) analytical procedures; ISO16649-3, ISO 6888-2, ISO 4833-1, ISO 9308-, ISO 10523:2017 ISO 7027: 2016, and ISO 7887: 2011 were used to determine the quality of disinfected and untreated water. The experimental design consisted of series collectors without heat exchanger, parallel collectors without heat exchanger and series arrangement of solar collectors with heat exchanger for preheating the cold incoming water using the exiting hot water. Total coliforms, total plate count, Staphylococcus aureus and Escherichia coli log10 counts in raw water were: 3.4, 3.8, 2.3 and 2.1 respectively. The mean Log10 reductions in total coliforms, Escherichia coli, Staphylococcus aureus and total plate counts were; 3.3, 1.9, 1.9 and 3.7 respectively in series arrangement with heat exchanger. Inactivation to &lt; 1 CFU/ml was attained using series collector’s arrangement with heat exchanger between 12:00 and 14:00. Parallel collector arrangement induced water pasteurization that required recirculation and low flow rates to effectively initiate microbiological inactivation. Staphylococcus aureus requires temperature greater than 48 °C to initiate inactivation. Series collector arrangement with heat exchanger produced 200 l of disinfected water per day. However, additional collectors and water recirculation are required to increase the volume of disinfected water.

Evaluation of the capacity of PET bottles, water aeration, and water recirculation to reduce evaporation in containers of water

ObjectivesTo evaluate the effectiveness of an evaporation reduction method in which the greater part of the water surface was covered with PET-type plastic bottles. The capacity of this method to diminish natural evaporation was compared to water aeration, water recirculation, and the control (without intervention). With evolutionary computation, including genetic algorithms and genetic programming, equations for calculating evaporation were developed based on meteorological factors. MethodsFour containers of water were placed on a flat roof in Mexico City (thus exposed to the factors of weather), and evaporation was measured daily with an evaporimeter. Each container was assigned to one of the evaporation reduction methods (PET bottles, water aeration, or water recirculation) or to the control (without intervention). Evaporation-related variables were selected according to previous reports and principal component analysis, and their values were acquired from a nearby meteorological station. The study was conducted from April of 2020 to February of 2021. ResultsCovering the water surface with PET bottles avoided 38.61% (a total of 139 mm) of natural evaporation, which is represented by the control. The water aeration and water recirculation methods diminished evaporation by 7.22% (26 mm) and 2.22% (8 mm), respectively. The best equations for estimating evaporation were obtained with genetic programming for the control container and a genetic algorithm for the container with PET bottles. ConclusionsThe PET bottle method of evaporation reduction was 7 and 17 times more effective than water aeration and water recirculation, respectively. The 38.61% decrease in evaporation achieved by covering the water surface with PET bottles constitutes a substantial savings in water. Hence, the implementation of such a method should be considered to contribute to water conservation in reservoirs. The use of PET bottles is a practical and inexpensive method requiring only a few cleaning maneuvers to prevent the proliferation of unwanted aquatic fauna.

Environmental Management Strategies in the Copper Mining Industry in Chile to Address Water and Energy Challenges—Review

The mining industry faces diverse challenges to maintain sustainable production, particularly regarding critical water and energy supplies. As a significant player in the copper mining industry, Chile has become a global reference. Therefore, this research analyses the distinct challenges of the Chilean copper mining industry in terms of water and energy. We also identified ten key challenges that the Chilean copper mining industry must address to remain competitive and relevant. Several mining companies were examined to review and understand the different types of Environmental Management Initiatives (EMIs) adopted. The most prevailing strategies involved implementing Environmental Management Systems, which allow organisations to define, implement, and track their specific goals and standards. This review acknowledged four relevant water-related initiatives, including seawater use, community strategic plans, general environmental monitoring programs, and water recycling and recirculation systems. In terms of energy, the key initiatives included energy efficiency projects, the use of Non-Conventional Renewable Energy (NCRE), and mine process optimisation. The benefits of implementing EMIs are multiple, with the most relevant being ensuring continuous operation, cost reduction, and improved Social License to Operate (SLO) outcomes.

PELATIHAN BUDIDAYA IKAN MAS DALAM KOLAM TERPAL DENGAN SISTEM RESIRKULASI

Carp (Cyprinus carpio) is a freshwater fish that is commonly cultivated because carp are large and tame when cultivated. In addition, carp can be bred and have a beautiful colours, moreover tend to famous among local people as a consumption fish, which is also can be used as ornamental fish. Carp can be cultivated in lowland waters to highland areas. In fish farmingm it is important to pay attention to good and clean water quality. Carp can be kept in earthen ponds, rushwater ponds, cages and also tarpaulin ponds. Carp rearing in tarpaulin ponds is usually carried out on narrow land and limited water ability. In there circumstances, it is necesarry to provide water that can support the life of carp to provide good quality of water is to do water recirculation. Resirculation technique is a water recycling technique that has been used. This technique basically performs physical, chemical and biological methods, but which is more environmentally friendly with physical and biological methods, for that in this activity physical and biological methods will be carried out using water filters from sand and aquatic plants. As a result, participants understand how good and correct cultivation techniques are, obtain information bioecology of carp, hatchery techniques, spawning techniques, resirculation techniques including threaten by various diseases and others causes in cultivation carp business. Furthermore, participants also gain more knowledge about what materials and proper equipment they should using and urgently needed to build a cultivation business on limited land and low water flow

Prevalence of opportunistic pathogens in a school building plumbing during periods of low water use and a transition to normal use.

The spread of opportunistic pathogens via building water supply and plumbing is of public health concern. This study was conducted to better understand microbial water quality changes in a LEED-certified school building during low water use (Summer) and normal water use (Autumn). The copper plumbed building contained water saving devices, a hot water recirculation system, and received chloraminated drinking water from a public water system. Three separate sampling events were conducted during the summer break inside the building and another three sampling events were conducted after the school returned to session. Using quantitative PCR, Legionella spp. were detected in all water samples, followed by Mycobacterium spp. (99%). Mycobacterium avium (75%) and Acanthamoeba spp. (17.5%) throughout the building water system. Legionella pneumophila and Naegleria fowleri were not detected in any of the samples. The mean concentrations of Legionella spp., Mycobacterium spp., Mycobacterium avium, and Acanthamoeba spp. detected in water samples were 3.9, 5.7, 4.7, and 2.8 log10 gene copies per 100ml, respectively. There was a statistically significantly difference in the mean concentrations of Legionella spp., Mycobacterium spp. and M. avium gene markers in water samples between school breaks and when school was in session. Cultivable Legionella were also detected in water samples collected during periods of low water use. This study highlights the need for routine proactive water quality testing in school buildings to determine the extent of drinking water quality problems associated with plumbing and direct action to remediate microbial colonization.

Numerical investigations on performance improvement of cross flow hydro turbine having guide vane mechanism

ABSTRACT Cross-flow turbine is one of the leading turbines to harness the hydropower potential in micro-hydro power schemes. In spite of having a simple structure, low maintenance, and low initial investment, this turbine suffers the problem of low efficiency due to unguided flow in the runner cavity. In the present study, an attempt has been made to enhance the performance of cross-flow turbine by attaching hydrofoils shaped (symmetrical and unsymmetrical) guiding mechanism. The effectiveness of the placement of guide vane was examined numerically in terms of turbine efficiency and flow field distributions. The performance of the modified turbine was compared with the turbine having no guide vane. The position and placement angle of the guide vanes were also investigated to find the suitable position of the guide vane in the runner cavity. The turbine with symmetrical and unsymmetrical guide vane yields its maximum efficiency corresponding to vane angle of 55° and 45°, respectively, placed at the ‘right’ position (toward nozzle) for both types of guide vanes. The maximum efficiency of the turbine was observed as 80.1% and 79.9% corresponding to symmetrical and unsymmetrical guide vanes, respectively. Further, the flow field distribution inside the turbine runner and in the vicinity of the guide vane has been observed. It has been visualized that placement of the guide vane minimizes the water recirculation with the streamlined flow for smooth entry to the second stage of the runner. The reduction in turbulence and vortices generation results in the improvement of turbine efficiency for similar operating conditions.

Comparative Study of Inlet Structure and Obstacle Plate Designs Affecting the Temperature Stratification Characteristics

Temperature stratification between outgoing hot water and incoming cold water is a key factor in diminishing energy loss during the discharging process and maximizing the useful hot water delivered from the tank or enhancing the thermal efficiency of the heating device during the heating process. In this study, the inlet structure and the obstacle plate were designed and modified based on two main factors, the reduction of inlet water velocity and the stipulation of the water recirculation area, to develop temperature stratification through the computational fluid dynamics method. The simulation model’s accuracy was validated against the experimental results. The results showed that using the equalizer as an inlet pipe’s auxiliary device was the best approach for decreasing the inlet water velocity, which resulted in enhancing temperature stratification. The discharging efficiency improved from 77.3% for the original tank model to 86.1% for the tank with equalizer IV model, which meant an additional 45 L of useful hot water was gained from the good temperature stratification storage tank. The installation of the obstacle plate for controlling the turbulence zone could not improve temperature stratification significantly, which resulted in an increase in discharging efficiency by only 4% more than the original tank model.

Influence of guava residue on tambaqui growth performance

Fruit residues represent alternative ingredients that can be included in diets of tambaqui, Colossoma macropomum. This study evaluated the growth performance of tambaqui fed diets containing different levels of guava agroindustrial residue. The experiment was based on a completely randomised design, with 105 fish randomly distributed in 15 plastic 60 L-1 boxes with a water recirculation system. Feeding was carried out to apparent satiety for 45 days, using diets with 0, 50, 100, 150 and 200 g kg-1 inclusion of guava residue. Biometrics were performed every 15 days. Quadratic effect (p &lt; 0.05) was observed for daily feed intake and apparent feed conversion, with optimum levels of 4.86 and 6.05% inclusion of guava residue, respectively. There was no significant difference (p &gt; 0.05) in relation to final weight, weight gain, specific growth rate, hepato-somatic index, survival rate and protein efficiency rate by the dietary treatments. The inclusion of up to 150 g kg-1 of the guava agroindustrial residue in the feed did not compromise the performance of tambaqui juveniles.

Effects of Stepwise Microwave Synergistic Process Water Recirculation During Hydrothermal Carbonization on Properties of Wheat Straw

In this study, wheat straw (WS) was treated using two-step synergistic techniques, which were process water recirculation (PWR) during hydrothermal carbonization (HTC) and microwave energy activation (MEA). The physicochemical properties of solid and liquid products during the process of HTC PWR were characterized. The temperature-rising properties, yields, and fuel properties of hydrochar after MEA were explored. Then the optimal technique conditions were explored. When HTC PWR was twice, the carbon content (55.59%) and higher heating value (21.72 MJ/kg) were the highest, and the ash content (1.93%) and the O/C and H/C ratios were the lowest. When HTC PWR was three times, the fixed carbon content, mass yield, and energy yield were the highest: 18.53%, 58.25%, and 71.84%, respectively. Many more carbon microspheres and pores appeared on the surface of hydrochar after PWR, which could improve the fuel characteristics and mass yield. After HTC PWR, the concentration of organic acids and HMF in liquid by-products increased, which was conducive to the increase of carbon content and mass yield. The best effect was HTC PWR twice or three times. With the increase of microwave power or the extension of microwave activation duration, the temperature-rising properties of hydrochar significantly increased, and the mass and energy yields decreased. The volatile contents of hydrochar decreased and their fixed carbon contents and HHV increased with the increase of microwave power. The properties of hydrochar could be improved when MEA was 900 W or 1000 W for 4 min. Therefore, MEA had significant effects on the properties of hydrochar after different PWR conditions.