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Environmental pollution has been a major concern in recent times, and soil and groundwater pollution are areas which have received particular focus. This has led to the development of various remediation techniques such as excavation, soil vapor extraction, bioremediation, chemical oxidation, and so on. Among all remediation techniques, chemical oxidation has been proven to be the most effective and feasible technique around the world. In this study, various combinations of ozone and hydrogen peroxide were used to treat diesel-contaminated soil and groundwater in an experimental setup. Experimental soil and groundwater were prepared with properties similar to the contaminated soil. An ozone generator and a pump injection system were deployed for combining ozone and hydrogen peroxide. Five different experiment batches were prepared based on the hydrogen peroxide concentration and its ratio to the soil. The diesel concentration in the water dropped from 300 mg/L to 7 mg/L in the first hour of treatment, which dropped below the detection limit (0.01 mg/L) thereafter. Similarly, 63.9% degradation was achieved with the combined sparging of ozone and hydrogen peroxide in the soil. Ozone combined with 7% hydrogen peroxide was the most promising combination for removing the contaminants. In addition, this research explored the hydroxyl radical conversion rate of ozone and the perozone, the difference in order of magnitude is greater than one which shows that the perozone has better oxidation capacity than ozone only. The findings of this study show that combining ozone with hydrogen peroxide is a competent and feasible onsite remediation method for diesel contaminants in soil and groundwater. Thus, this method can be applied in local gas stations, accidental spillage sites, and small-scale refineries for onsite treatment in a cost-effective and technically sound way within a short time span.

A high performance compact MMIC class F power amplifier is demonstrated for 5G small cell applications by a 0.25-μm Gallium Nitride (GaN) High Electron Mobility Transistor (HEMT) technology. Both the 2nd and 3rd harmonic terminations are considered in the output matching network, and optimized utilizing the backside via parasitic inductance. Also, the device drain-source parasitic capacitance is considered together into the matching circuit for improving the bandwidth and high frequency operation. The measured peak output power P out of the amplifier is 36.6 dBm at 6 GHz. Also, the measured peak power-added-efficiency (PAE) at a 1.5 dB gain compression is 65.8 %. Also, the measured 3-dB bandwidth is 1800 MHz. The design has a chip size of only 2.56 mm2.

This study investigated the feasibility of using electrolysis of water to produce hydrogen and oxygen that were used as the electron donor and the electron acceptor for the anaerobic reductive dechlorination and the aerobic cometabolism of chlorinated ethylene contaminants, respectively. By employing the anaerobic and aerobic conditions in different sections of a column test, intermediates formed in the anaerobic dechlorination of PCE in the up-gradient section were further biodegraded through aerobic cometabolism in the down-gradient section, which used methane as the primary substrate. The results indicated that, the effluent PCE concentration was 0.88 μmol l−1 when the influent PCE concentration was 60 μmol l−1, up to 98.5% PCE was degraded in 160 days with an additional current density up to 0.099 mA cm−2. The First-order reaction rate was increased by 1.9–17.3 times with biostimulation by electrolysis method, showing that the benefits of an integrated electrochemistry and biotransformation system to complete mineralization of tetrachloroethylene. In addition, the specific microbial populations of Dehalococcoides sp. and methane-oxidizing bacteria were analyzed using the ethidium monoazide-PCR procedure, indicating the presence of viable bacteria in the integrated system.

Groundwater at trichloroethylene (TCE)-contaminated sites lacks electron donors, which prolongs TCE’s natural attenuation process and delays treatment. Although adding electron donors, such as emulsified oil, accelerates TCE degradation, it also causes the accumulation of hazardous metabolites such as dichloroethylene (DCE) and vinyl chloride (VC). This study combined in situ chemical reduction using organo-iron compounds with enhanced in situ bioremediation using emulsified oil to accelerate TCE removal and minimize the accumulation of DCE and VC in groundwater. A self-made soybean oil emulsion (SOE) was used as the electron donor and was added to liquid ferrous lactate (FL), the chemical reductant. The combined in situ chemical reduction and enhanced in situ bioremediation achieved favorable results in a laboratory microcosm test and in an in situ biological field pilot test. Both tests revealed that SOE+FL accelerated TCE degradation and minimized the accumulation of DCE and VC to a greater extent than SOE alone after 160 days of observation. When FL was added in the microcosm test, the pH value decreased from 6.0 to 5.5, however, during the in situ biological pilot test, the on-site groundwater pH value did not exhibit obvious changes. Given the geology of the in situ pilot test site, the SOE+FL solution that was injected underground continued to be released for at least 90 days, suggesting that the solution’s radius of influence was at least 5 m.

Chlorinated aliphatic hydrocarbons generally cannot be used as the carbon source or energy source for microorganism growth; these compounds are more difficult to be biodegraded by microorganisms in groundwater. The objective of this study was to explore the growth and degradation capability of aerobic mixed culture in a sand column simulating a PCE and DEC-contaminated aquifer. Results of the biostimulation study indicated that DCE removal rate was 60% after the operation of 56 days. With the bioaugmentation of aerobic mixed culture, DCE removal rate could be enhanced by 100% in the upstream of a simulated aerobic aquifer after the operation of 105 days. Bioremediation was conducted by addition of mixed aerobic bacteria that can degrade dichloroethylene to investigate the biodegradation of dichloroethylene in a simulated anaerobic and aerobic groundwater system. The results of column tests show that the pollutants in the downstream of the simulated anaerobic aquifer mainly comprised dichloroethylene, vinyl chloride, and methane. Fourteen days after mixed aerobic bacteria were added to the simulated aerobic aquifer, the removal efficiency of most intermediates generated from the anaerobic biodegradation process reached approximately 99%, indicating that the combined anaerobic-aerobic system accelerated the degradation of tetrachloroethylene and dichloroethylene.

The aim of this study was to introduce 5% up to 40% of low grade silicon carbide (LGSC), with construction excavated soil before the soil being reused as raw material in Eco brickmaking. Furthermore, stone sludge was added to mix with LGSC to fabricate eco bricks. The results indicated that the use of 10% granite sludge, 30% LGSC and 5% brick waste clinkers could produce grade-2 eco bricks in sintering temperature 1,050°c, however 30% granite sludge was substituted to obtain the same grade eco bricks. Water absorption of eco bricks has increased during the addition ratio of LGSC increased. However, the compressive strength increased while water absorption decreased during the operation temperature increased from 1,020°c. to 1,050°c.

Heavy metals from the electroplating wastewater might cause environmental pollution if not well treated. Generally, carbon adsorption might be used for the final step for further trace metals removal. This study investigated the heavy metal Cu adsorption in the fixed bed column with 1, 10 and 100 mg/L influent concentration. Results showed that KAB decreased as influent Cu concentration increased from 1 to 100 mg/L while N0 increased as influent concentration increased from 1 to 100 mg/L as can be found in Adams-Bohart model. R2 was found between 0.8579 and 0.9182. In Thomas model. KTH and q0 showed the similar trend as KAB and N0 in the Adams-Bohart model. KTH decreased as influent Cu concentration increased from 1 to 100 mg/L. q0 increased as influent Cu concentration increased from 1 to 100 mg/L. R2 of regression model was found between 0.9065 and 0.9836. In Yoon-Nelson model. KYN increased as influent Cu concentration increased from 1 to 100 mg/L while τ decreased as influent Cu concentration increased from 1 to 100 mg/L. Results showed that the three models of Adams-Bohart model, Thmoas model and The Yoon-Nelson model were suitable for the description of Cu adsorption by activated carbon.

Several remediation technologies were evaluated in this study to efficiently break down lubricant in contaminated soil, including chemical oxidation, bioremediation, and the combination of chemical oxidation and bioremediation. The chemical oxidation batch experiment results indicated that when soil pH was acidified to 3.0, traditional Fenton's oxidation most effectively removed lubricant in contaminated soil. However, this method may cause permanent damage to the ecosystem since it requires acidic soil conditions. Further experimentation showed that by adding citric acid to traditional Fenton's oxidation, this modified Fenton's process oxidized the lubricant even more efficiently, by forming an effective chelation and preventing the production of ferric oxide precipitates, all under neutral soil conditions. In the bioremediation tests, results showed that lubricant degradation efficiencies improved by adding peptone and glutamate salt, since they served as nutrients for the soil microbes. Overall, the combination of a 56 d biopile with ammonium chloride and monosodium glutamate, followed by a modified Fenton's oxidation, was found to be the optimal degradation approach in lubricant-contaminated soil, with a promising 99.2% removal efficiency for an initial concentration of 10,000 mg kg−1 of lubricant.

Laboratory experiments were conducted at 20–25°C to compare the performance of three different types of Captor media with a rock-gravel media and a plastic trickling filter-packing media. The open-cell Captor media performed better than the gravel media and plastic trickling filter media at all loading rates up to 0.592 kg NH3-N/m3/d. Even at the highest NH3-N loading rate, the effluent NH3-N concentration was less than 1.0 mg/L in the open-cell Captor media effluent. The closed-cell, carbon-impregnated Captor media did not perform as well as the open-cell media. The reduction of temperature to 10–12°C reduced the performance of the Captor system to some extent, but NH3-N levels of less than 1.0 mg/L were obtained at loading rates up to 0.339 kg NH3-N/m3/d. At the highest NH3-N loading rate tested (0.852 kg NH3-N/m3/d), the nitrification performance of all the systems decreased, probably due to D.O. limitations, increased BOD loading and the consequent displacement of the nitrifiers by the heterotrophic organisms and lower detention time.