Quantum efficiencies of the photo-Fenton degradation of atrazine in water

An experimental work in a well-stirred batch recycling reactor for the photo-Fenton degradation of atrazine in water is presented. A study of the quantum efficiency is performed to assess the effectiveness of the photo-Fenton process on the atrazine degradation and total organic carbon (TOC) mineralization. Apparent and absolute quantum efficiencies of degradation and mineralization of an atrazine-based commercial herbicide are determined under different experimental conditions. Higher apparent efficiencies were found for both atrazine degradation and TOC mineralization when the ferric ion and hydrogen peroxide concentrations are increased. Because of the well known stability of the triazine ring, atrazine was not completely mineralized by the photo-Fenton process. However, a TOC reduction of 40% was achieved, being 62.5% of the maximum value that can be reached.

Biological sulfide removal under alkaline and aerobic conditions in a packed recycling reactor

The biological sulfide removal from wastewater caustic streams can be achieved without significant dilution by alkaliphilic microorganisms which usually show lower growth and oxidation rates as compared with acidic and neutral bacteria. To improve volumetric removal rates under alkaline condition (pH 10), an Alkaliphilic Sulfide-oxidizing Bacteria Consortium (ASBC) was studied in a Packed Recycling Reactor (PRR). A commercial Nylon fiber resulted to be a convenient packing support for biofilm development as it has high specific area and similar hydrophobic propertie. The PRR reached a maximum sulfide oxidation rate of 100 mmol L−1 d−1 with efficiency close to 100%, representing an enhancement of 56% from the maximum sulfide oxidation rate reached for a free cell continuous culture. Higher sulfide loading rates induced oxygen limiting conditions reducing the biological activity despite the considerable biofilm attached on the nylon fiber.

Advanced Recycling Reactor Design Study

The Advanced Recycling Reactor (ARR) design study sponsored by DOE of USA has been conducted [1]. This paper presents the pre-conceptual design of the ARR that is a loop-typed sodium cooled reactor with MOX fuel. The International Nuclear Recycling Alliance (INRA) takes advantage of international experience and agreed to use Japan Sodium-cooled Fast Reactor (JSFR) [2] as reference for Funding Opportunity Announcement (FOA) studies [1]. Since the scale-up factor of two is acceptable increase from manufacturing and licensing points of view, INRA proposes 3 evolutions of the ARR; ARR1, a 500 MWe demonstration plant, online in 2025; ARR2, a 1,000 MWe commercial plant, online in 2035; ARR3, a 1,500 MWe full-scale commercial plant, online in 2050. Japan has conducted R&Ds for the JSFR incorporating thirteen technology enhancements expected to improve safety, enhance economics, and increase reactor reliability. The ARR design is based on such the technology enhancements that it can benefit from this development effort and the ARR3 can become cost competitive with the similar sized LWRs. Major features of key technology enhancements are the following: Decay heat can be removed by natural circulation to improve safety. The primary cooling system consists of two-loop system and the integrated IHX/Pump to improve economics. The steam generator with the straight double-walled tube is used to improve reliability. The reactor core of the ARR1 is 70 cm high. The conversion ratio of fissile is set up less than 0.6 and the amount of burned TRU is 45–51 kg/TWeh. The ARR1 consists of a reactor building (including reactor auxiliary facilities and electrical / control systems), a turbine building, and a reprocessing building. The dimensions of the overall reactor building will be 46.1 m (W) × 72.8 m (L) × 70.3 m (H), and the volume of the building will be approximately 180,000 m3.