Landfill leachate of Hong Kong was first treated by the upflow anaerobic sludge blanket (UASB) process. At 37 degrees C, pH 7.1-8.5 and a HRT of 5.1-6.6 days, the process removed 66-90% of COD in the leachate for loading rates of 1-2.4 g-COD/l day depending on the strength of landfill leachate. The final effluent contained 1440-1910 mg-COD/l and 70-91 mg-BOD/l. About 92.5% of the total COD remo...

Addition of H202 has been employed to repress bromate formation during ozonation of bromide-containing source water. However, the addition of H2O2 will change the oxidation pathways of organic compounds due to the generation of abundant hydroxyl radicals, which could affect the removal efficacy of trihalomethane precursors via the combination of ozone and biological activated carbon (O3-BAC). I...

the activated sludge process is the most widely used biological wastewater treatment for both domestic and industrial plants in the world. one of the drawbacks of conventional activated sludge (cas) processes is high sludge production. excess sludge treatment and disposal currently represents a rising challenge for wastewater treatment plants (wwtps) due to economic, environmental and regulatio...

In the present study the treatment efficiency of O3 and UV+O3 processes were compared for the oxidation of simulated dyebath effluent containing a mixture of a reactive dye (C.I. Reactive Blue 19) and various dye auxiliary chemicals. The color, COD and TOC removal rates were assessed for different processes. The effect of initial dye concentration and presence of sodium hydroxide and sodium car...

When ozonation is employed in advanced water treatment plants to produce drinking water, dissolved organic matter reacts with ozone (O3) and/or hydroxyl radicals (OH) affecting disinfection byproduct (DBP) formation with subsequently used chlorine-based disinfectants. This study presents the effects of varying exposures of O3 and •OH on DBP concentrations and their associated toxicity generated...

Traces of active pharmaceutical ingredients (APIs) and other chemicals are demonstrated in effluents from sewage treatment plants (STPs) and they may affect quality of surface water and eventually drinking water. Treatment of effluents with granular activated carbon (GAC) or ozone to improve removal of APIs and other contaminants was evaluated at two Swedish STPs, Käppala and Uppsala (88 and 10...

Ozonation followed by biological activated carbon (O3/BAC) is being considered as a key component of reverse osmosis-free advanced treatment trains for potable wastewater reuse. Using a laboratory-scale O3/BAC system treating two nitrified wastewater effluents, this study characterized the effect of different ozone dosages (0-1.0 mg O3/mg dissolved organic carbon) and BAC empty bed contact time...

This work evaluates the efficiency of different advanced oxidation processes (Fenton method, O3, H2O2 and O3/H2O2) for removing total COD (TCOD) and colour from biologically pre-treated swine manure. The Fenton process with a dosage of 100 mg L(-1) of Fe(2+) and 800 mg L(-1) of H2O2 resulted in about 78% TCOD and 96% colour reductions at an initial pH=3 after a reaction time of 30 min. Coagulat...

Effectiveness of ozonation before and after biological treatment for removal of recalcitrant organic matter in bleached kraft pulp effluents was compared. Two industrial ECF bleached eucalypt kraft pulp effluents (E1 and E2) were pretreated with 100 mg O3/L. Raw and pretreated effluents were treated biologically in bench-scale sequencing batch reactors, under constant conditions. Following biol...

We used conventional ozonation and the AOP O3/H2O2 to estimate the required energy to achieve the desired pre-defined level of oxidation of target organic micropollutants by hydroxyl radicals. We used the probe compound para-chloro benzoic acid (pCBA) to assess the fraction of OH available for oxidation of micropollutants. pCBA reacts slowly with O3 but reacts very fast with OH (kOH,pCBA = 5 x ...