Effects of organic carbon content on in situ remediation time using steam–air injection

Groundwater contamination by chlorinated hydrocarbons (CHC) is a common phenomenon that poses health risks to both humans and animals. These halogenated hydrocarbons infiltrate into the soil matrices and form pools at the bottoms of the aquifers thus contaminating the groundwater sources. Thermally enhanced soil vapour extraction (TSVE) using steam–air injection has gained popularity as an alternative technique to remediate the saturated and vadose source zones contaminated with CHC. This technique has been successfully applied in the remediation of contaminated sites (brownfields, industrial sites) and groundwater. However, the presence of organic carbon (OC) contents within the soil matrices has not been intensively studied. This paper, therefore, intends to contribute toward increasing the understanding of the effects of OC on the remediation time using TSVE. A 2-D flume experimental model was conducted in VEGAS laboratory using coarse sand, fine sand and silty soil with 0, 1 and 2% addition of the activated carbon as OC to investigate the desorption time of PCE and TCE as CHC during TSVE extraction using steam–air injection. 100 kg of soil mixed with the activated carbon was treated with 50 g TCE and 50 g PCE and then remediated using TSVE. The remediation times were recorded and recovered CHC was documented. It was discovered that the presence of OC enhanced the adsorption of the CHC onto the soil matrices thereby increasing the time required for the complete remediation of the contaminant from the soil. An increase of OC by 1% resulted in desorption time by a factor of 4–7.

A Comparative Study on the use of Soil - Organic and Inorganic Biostimulants in the Remediation of Oily Waste

Remediation of oily waste using soil-organic (goat dung, poultry dropping) and inorganic (NPK fertilizer) nutrients was assessed for twelve weeks using culture-dependent microbiological technique and chemical procedures. The results indicate increased counts of Hydrocarbon-utilizing bacteria, fungi and actinomycetes with remediation time for both nutrient types. Bacteria in the remediated waste were members of the genera Bacillus, Pseudomonas, Acinetobacter, Alcaligenes and Serratia, fungi: Penicillium, Aspergillus and Cladosporium, and actinomycetes: Rhodococcus, Nocardia and Streptomyces for all soil-nutrient amendment techniques. pH of the NPK fertilizer ranged between 6.7 ± 0.03 and 7.3±0.06 whereas the goat dung and poultry dropping amendments was 6.5± 0.02 and 7.1 ±0.05. Dehydrogenase activity increased for the biostimulant treatment cells with remediation time. Total Petroleum Hydrocarbon reduction was 99.3 and 99.6% in organic and 99.8% for inorganic amendments. Polycyclic Aromatic Hydrocarbons of the remediated waste for both techniques revealed values below detectable limits (< 0.01) at the end of remediation period. Remediation with soil-goat dung and soil-poultry dropping amendments compared favorably with soil-NPK fertilizer technique because microbial activities were enhanced to produce eco-friendly waste. The use of soil-organic amendments is therefore a low-cost alternative biostimulant for the management of oily waste in the petroleum industry.

Response Surface Method Analysis on Electro-Enhanced Technique for Remediation of Cadmium Contaminated Soil

In view of the problems of long remediation time, high energy consumption and low remediation efficiency in electrokinetic remediation of heavy metal contaminated soil, Cd was used to simulate heavy metals in contaminated soil, and response surface method (RSM) was used to optimize the factors influencing electrokinetic remediation. Central Composite (CCD) experimental design method was taken to study the effects of electric field strength, remediation time and water content on removal rate of Cd in soil. Also, polynomial regression mathematical model and optimal reaction conditions were provided for Cd pollution in electrokinetic soil remediation. The simulated equation F was 15.67, the correlation coefficient was 0.9338, and the adjustment correlation coefficient was 0.9042, indicating good regression and strong significance of the equation. The model results showed that, for the optimal experimental conditions, electric field strength was 2.25V·cm-1, the remediation time was 120.79h, and the water content was 17.06%. On the basis of such reaction condition, intermittent current flow method was adopted d to further enhance the electrokinetic remediation effect. The cadmium removal rate in the soil was increased by 3.17%, 2.86% and 2.43%, respectively, and the electric energy consumption was decreased by 10.54%, 11.28% and 9.97%, respectively, suggesting that the method could effectively improve the removal rate of Cd and reduce energy consumption.

Parapets, Politics, and Making a Difference: Lessons from Christchurch

At 12:51 on 22 February 2011, 12 people died beside me. The parapet and facade of an unreinforced masonry building on the main street of Christchurch, New Zealand, crushed the bus that I was riding. I'm the only one left, the lucky 13th. My leg, my hand, and my soul will never be the same. I broke more bones than the surgeons were willing to count, spent two months in the hospital, and most of a year off work. I walked, slept, and dreamed in a fog for four years. It cost half a million dollars to save my left leg. I treasure that leg, scars and all, but still feel the earthquake in every step. In this opinion paper, I share my story—from the earthquake, to the Bright Light, to the Dark Place, to the hospital, to the Dalai Lama, to the halls of Parliament. I also share the story of a nation coming to grips with its home on the Ring of Fire. The story ends on 8 May 2016, when Parliament passed the new Building Act, complete with a ministerially titled “Brower Amendment” that halved the remediation time for unreinforced masonry parapets and other falling hazards. I conclude with the lessons I've learned on making a difference.

Removal of cadmium and zinc from contaminated wastewater using Rhodobacter sphaeroides

Rhodobacter sphaeroides was used for bioremediation of wastewater polluted with cadmium (Cd) and zinc (Zn). The tolerance of the microorganism to selected heavy metals (HMs), as well as the effects of pH, temperature and inoculum size on the removal rate, was investigated. The remediation effects of R. sphaeroides were analysed at different initial concentrations of HMs. Bioremediation mechanisms were thoroughly discussed based on the results from the cell characterisation analysis. Cd and Zn could inhibit the growth of R. sphaeroides. However, Cd was more toxic than Zn, with corresponding EC50 values of 5.34 and 69.79 mg L−1. Temperature and pH had greater influence on the removal rate of HMs than inoculum size. The optimal conditions for temperature and pH were 35 °C–40 °C and pH 7, respectively. Initial concentration of HMs and remediation time also affected the removal rate. Rhodobacter sphaeroides had a relatively higher remediation effect under the present experimental conditions. The removal rates for Cd and Zn reached 97.92% and 97.76%, respectively. Results showed that biosorption and HM precipitation were the main bioremediation mechanisms. This information is necessary to better understand the removal mechanism of R. sphaeroides, and is significant for its pilot test and future practical application.

A Design of Continuous and Universal In Situ Remediation Appliance of Soil Combines

Continuous and universal in-situ remediation appliance of soil combines taking soil, transmission and restoration of soil, which can achieve the in-situ remediation continuously and avoid the drawback of massive labor power and material resources using domestic soil ex-situ remediation device. The appliance supports many kinds of soil remediation technology, realizing the function of universal technology. And as for the area with serious pollution, various technology combinations can be selected to extend its function. The motion of specific remediation device in the appliance utilizes the single-chip controlling technology, controlling the remediation time interval of different technology. The program selection with various remediation technologies can be finished with buttons. Single-chip controlling system responds quickly, runs stably and precisely controls the remediation device.

ELISA Applied on Survey and Remediation of Dioxin Contaminated Site - A Case Study in Southern Taiwan

Once the pollution was found in a preliminary survey, the related information about the pollution site should be collected to confirm polluted range and quantity. Appropriate remediation technology is implemented until the pollution is completely remove. The more precise survey could lower the risk of uncertainty and improve the site remediation process. However, numerous of sampling and analysis should be done during whole process, including pollution survey, evaluation of remediation effectiveness, and verification after remediation. Time and budget needed for the remediation will be huge loads because of the widely range of site, and characteristics of the complicated pollutants, which may affect the remediation process. This study utilities Enzyme-Linked ImmunoSorbant Assay (ELISA) as the screening tool for dioxin pollutants by means of immuno-biological assay, which can complete the detailed investigation quickly and effectively, and also the pollution reclamation in a short time with the independent quality control. An appropriate screening method plays an important role for a successful and effective remediation.