Transformation in Bulk and Trace Organics during Ozonation of Wastewater

The aim of this paper is to determine the ozone dosages needed to oxidize bulk and trace organics. Treated effluent from eight full-scale wastewater treatment plants was collected and subjected to lab-scale ozonation. Because both organics and inorganics exert ozone demand, an approach was developed to calculate only the ozone demand associated with organics. This method allowed normalization of dosing parameters to correlate with removal of color, UV absorbance, plus oxidation of trace organics and nitrosamine precursors. We also showed that ozonation effectively reduces the fraction of organic matter characterized as “colloidal organic matter,” thereby reducing the potential for membrane fouling.     

Effect of processing conditions on organics in wastewater from hydrothermal dewatering of low-rank coal

A study was carried out into the effects of processing conditions on the nature and amounts of organics released into wastewater from hydrothermal dewatering (HTD) of low-rank coal. Processing conditions examined included temperature, residence time, water to coal ratio in the slurry, slurry loading, and coal lithotype. High temperature and pressure treatments of low-rank coal slurries were used to simulate the HTD process. It was found that the extent of extraction of organics during HTD processing depended on the coal lithotype and increased with increasing temperature, residence time, and the proportions of steam and water present during processing. For a constant residence time, the concentration of organics in the wastewater increased exponentially with temperature over the temperature range 250-350 °C. A maximum level of approximately 7 g/l (expressed as TOC) of organics was observed following processing at 350 °C. Hot filtration of the coal slurry produced a higher organics loading compared to that found in wastewater obtained at low temperature.     

有机物复合淀粉胶黏剂的研究进展

淀粉胶黏剂作为一种绿色环保型产品,被广泛应用于纸张、啤酒贴标及瓦楞纸板等生产线。生产速度的提高使得胶黏剂原料由单一的淀粉转变为复合组分。特别是淀粉与有机物质复合以后,其性能改观更为明显。主要表现为流动性好、耐水性强、初黏力强、干燥速度快、无毒、无污染等。综述了国内有机物复合淀粉胶黏剂的研究概况,介绍了有机高分子特别是聚乙烯醇、干酪素与淀粉复合,以及小分子与淀粉复合的工艺及产品特点,并对其前景进行了展望。     

Investigation on removing recalcitrant toxic organic polluters in coking wastewater by forward osmosis

Investigation was made on the efficiency of two commercial membranes in removing via forward osmosis (FO) the low molecular weight organic compounds typical of coking wastewater. The membranes were supplied by Poten and HTI companies. The organics in the simulated coking water were indole and pyrridine. Under FO mode, the rejection to the organics by Poten membrane was around 50%, whereas that for HTI membrane was obviously higher, ranging from 65% to 74%. The response of the two membranes in terms of Water flux and reverse salt flux (RSF) towards changing feed/draw solution (DS) flow rates in FO mode showed similar tendency, but different degree. Generally, the flux in FO using HTI membranes was lower. For HTI membrane, FO operated with pressure retarded osmosis (PRO) mode was also performed and the overall rejection of the organics was slightly lower than that in FO mode. In the long term FO test within 15 days, both Poten and HTI membranes displayed flux reduction and rejection enhancement. But the variation with Poten membrane was much more obvious. Discussion was carried out about the reasons and the mechanisms behind the FO performance difference between two membranes and the variation in flux and rejection with operation conditions. Characterizations by SEM, FTIR, AFM, XRD and XPS were tried to support the proposed explanations.     

The Influence of H2O2 in Ozonation Treatment: Experience of the Water Supply Service of Florence,Italy

This paper reports on the use of ozone in the Water Supply Service of Florence (Italy). The addition of hydrogen peroxide at the end of ozonation treatment has proved particularly efficient for controlling bromates and brominated organic byproducts. Significant differences regarding the formation of oxygenated organic compounds were not observed.     

Photocatalytic degradation of oil industry hydrocarbons models at laboratory and at pilot-plant scale

Photodegradation/mineralization (TiO₂/UV Light) of the hydrocarbons: p-nitrophenol (PNP), naphthalene (NP) and dibenzothiophene (DBT) at three different reactors: batch bench reactor (BBR), tubular bench reactor (TBR) and tubular pilot-plant (TPP) were kinetically monitored at pH = 3, 6 and 10, and the results compared using normalized UV light exposition times. The results fit the Langmuir-Hinshelwood (LH) model; therefore, LH adsorption equilibrium constants (K) and apparent rate constants (k) are reported as well as the apparent pseudo-first-order rate constants,  = kK/(1 + Kc_r). The batch bench reactor is the most selective reactor toward compound and pH changes in which the reactivity order is: NP > DBT > PNP, however, the catalyst adsorption (K) order is: DBT > NP > PNP at the three pH used but NP has the highest k values. The tubular pilot-plant (TPP) is the most efficient of the three reactors tested. Compound and pH photodegradation/mineralization selectivity is partially lost at the pilot plant where DBT and NP reaches ca. 90% mineralization at the pH used, meanwhile, PNP reaches only 40%. The real time, in which these mineralization occur are: 180 min for PNP and 60 min for NP and DBT. The mineralization results at the TPP indicate that for the three compounds, the rate limiting step is the same as the degradation one. So that, there is not any stable intermediate that may accumulate during the photocatalytic treatment.     

Scarcity and Abundance: Urban Agriculture in Cuba and the US

In urban agriculture, there is a direct connection between scarcity and abundance: with the threat of food shortages so often acting as an effective trigger for food-growing enterprises. Produce can also be grown with few or limited resources. André Viljoen and Katrin Bohn of Bohn&Viljoen Architects juxtapose the experience of the organopónicos, or market gardens, in Cuba, which have proliferated since the US trade blockade of the 1990s and ensuing fuel shortages, and more recent experiments in food production in North American cities that are learning from their example.     

Analyses of organics in irradiated aqueous N, N-diettiyihydroxylamine solution

The organics in γ-ray irradiated aqueous N, N-diethylhydroxylamine （DEHA） solution, which is used as a reducing agent in reprocessing spent nuclear fuel, were analyzed with gas chromatography equipped with FFAP capii- lary colunm and flame-ionization detector. It was found that irradiated DEHA solutions contained acetaldehyde, ethanol, and acetic acid. For DEHA of 0.2 mol/L irradiated to 10-1000 kGy, the concents of acetaldehyde, ethanol and acetic acid are （9.7-18.7）×10^3, （0.4-23.4）×10^3 and （6.5-11.7）×10^3 mol/L, respectively. The concentration of DEHA decreases obviously with the dose.     

The use of hybrid constructed wetlands for wastewater treatment with special attention to nitrogen removal: A review of a recent development

The hybrid systems were developed in the 1960s but their use increased only during the late 1990s and in the 2000s mostly because of more stringent discharge limits for nitrogen and also more complex wastewaters treated in constructed wetlands (CWs). The early hybrid CWs consisted of several stages of vertical flow (VF) followed by several stages of horizontal flow (HF) beds. During the 1990s, HF–VF and VF–HF hybrid systems were introduced. However, to achieve higher removal of total nitrogen or to treat more complex industrial and agricultural wastewaters other types of hybrid constructed wetlands including free water surface (FWS) CWs and multistage CWs have recently been used as well. The survey of 60 hybrid constructed wetlands from 24 countries reported after 2003 revealed that hybrid constructed wetlands are primarily used on Europe and in Asia while in other continents their use is limited. The most commonly used hybrid system is a VF–HF constructed wetland which has been used for treatment of both sewage and industrial wastewaters. On the other hand, the use of a HF–VF system has been reported only for treatment of municipal sewage. Out of 60 surveyed hybrid systems, 38 have been designed to treat municipal sewage while 22 hybrid systems were designed to treat various industrial and agricultural wastewaters. The more detailed analysis revealed that VF–HF hybrid constructed wetlands are slightly more efficient in ammonia removal than hybrid systems with FWS CWs, HF–VF systems or multistage VF and HF hybrid CWs. All types of hybrid CWs are comparable with single VF CWs in terms of NH₄-N removal rates. On the other hand, CWs with FWS units remove substantially more total nitrogen as compared to other types of hybrid constructed wetlands. However, all types of hybrid constructed wetlands are more efficient in total nitrogen removal than single HF or VF constructed wetlands.     

Impact of support media in an integrated biofilter-submerged membrane system

The impact of a support material on an integrated biofilter-membrane system, simulating a difficult-to-treat surface water, was examined in terms of membrane fouling rate and water quality parameters. The support media in the membrane tanks did not generally affect any of the water quality parameters measured; however, there was an observable difference in the membrane fouling rates between the two processes with the support media system fouling at least two times slower than the non-support system. Total organic carbon (TOC) removals at around 60% were observed for two integrated biofilter-immersed membrane processes with the majority of the TOC removal occurring in the biofilters. One of the membrane tanks contained a support media (Process A) while the other did not (Process B). The feedwater contained humic acid (65% w/w) and readily biodegradable carbons (35% w/w) in the forms of acetic acid, formic acid and formaldehyde. The influent TOC values were between 3.35 and 3.94 mg/L. Acetate removals varied between 66 and 83%, while over 90% of the formate was removed and the formaldehyde was completely removed in the biofilters. There was a decrease in the UV absorbance values by over 70% for both processes.