Removals of pharmaceutical compounds from hospital wastewater in membrane bioreactor operated under short hydraulic retention time.

Pilot-scale membrane bioreactor (MBR) was operated at a short hydraulic retention time (HRT) of 3 h for the treatment of hospital wastewater. The removals of eleven pharmaceutical compounds in MBR operated at different mixed liquor suspended solids (MLSS) level were investigated during which nitrification degree was differed. The results experiments revealed the importance of immediate adsorption onto the colloidal particles in supernatant of MBR sludge and subsequently removed by membrane filtration for the recalcitrant pharmaceutical compounds. Nevertheless, the removals through biodegradation during short HRT were also found significant for some compounds. DGGE profile revealed the development of pharmaceutical degrading microorganisms in MBR.

Organic carbon recovery and photosynthetic bacteria population in an anaerobic membrane photo-bioreactor treating food processing wastewater.

Purple non-sulfur bacteria (PNSB) were cultivated by food industry wastewater in the anaerobic membrane photo-bioreactor. Organic removal and biomass production and characteristics were accomplished via an explicit examination of the long term performance of the photo-bioreactor fed with real wastewater. With the support of infra-red light transmitting filter, PNSB could survive and maintain in the system even under the continual fluctuations of influent wastewater characteristics. The average BOD and COD removal efficiencies were found at the moderate range of 51% and 58%, respectively. Observed photosynthetic biomass yield was 0.6g dried solid/g BOD with crude protein content of 0.41 g/g dried solid. Denaturing gradient gel electrophoretic analysis (DGGE) and 16S rDNA sequencing revealed the presence of Rhodopseudomonas palustris and significant changes in the photosynthetic bacterial community within the system.

Removal of organic micro-pollutants from solid waste landfill leachate in membrane bioreactor operated without excess sludge discharge.

Two-stage membrane bioreactor (MBR) system was applied to the treatment of landfill leachate from a solid waste disposal site in Thailand. The first stage anoxic reactor was equipped with an inclined tube module for sludge separation. It was followed by an aerobic stage with a hollow fiber membrane module for solid liquid separation. Mixed liquor sludge from the aerobic reactor was re-circulated back to anoxic reactor in order to maintain constant mixed liquor suspended solids (MLSS) concentration in the aerobic reactor. The removal of micro-pollutants from landfill leachate along the treatment period of 300 days was monitored. The results indicated that two-stage MBRs could remove biochemical oxygen demand (BOD), chemical oxygen demand (COD) and NH(4)(+) by 97, 87 and 91% at steady operating condition. Meanwhile organic micro-pollutant removals were 50-76%. The removal efficiencies varied according to the hydrophobic characteristic of compounds but they were improved during long-term MBR operation without sludge discharge.

Photosynthetic bacteria production from food processing wastewater in sequencing batch and membrane photo-bioreactors.

Application of photosynthetic process could be highly efficient and surpass anaerobic treatment in releasing less greenhouse gas and odor while the biomass produced can be utilized. The combination of photosynthetic process with membrane separation is possibly effective for water reclamation and biomass production. In this study, cultivation of mixed culture photosynthetic bacteria from food processing wastewater was investigated in a sequencing batch reactor (SBR) and a membrane bioreactor (MBR) supplied with infrared light. Both photo-bioreactors were operated at a hydraulic retention time (HRT) of 10 days. Higher MLSS concentration achieved in the MBR through complete retention of biomass resulted in a slightly improved performance. When the system was operated with MLSS controlled by occasional sludge withdrawal, total biomass production of MBR and SBR photo-bioreactor was almost equal. However, 64.5% of total biomass production was washed out with the effluent in SBR system. Consequently, the higher biomass could be recovered for utilization in MBR.

Removal of pollutants and reduction of bio-toxicity in a full scale chemical coagulation and reverse osmosis leachate treatment system.

Removals of pollutants and toxic organic compounds and reduction in bio-toxicity of leachate along an operating full-scale leachate treatment system utilizing chemical coagulation, sand filtration, microfiltration (MF) and reverse osmosis (RO) membrane were evaluated. High pollutant removals were achieved mainly by coagulation and sand filtration. Major toxic organic pollutants, i.e. DEHP, DBP and bisphenol A were removed by 100%, 99.6% and 98.0%. Acute toxicity test using water flea, Nile Tilapia and common carp and genotoxicity (Comet assay) were conducted to determine toxicity reduction in leachate along the treatment. Ammonia was found to be the main acute toxic compounds in leachate as determined by LC(50) but the effect of organic substances was also observed. DNA damage in fish exposed to diluted raw leachate (10% of LC(50)) was found to be 8.9-24.3% and it was subsequently decreased along the treatment. Correlation between pollutants and its bio-toxicity was established using multivariable analyses.

Treatment performance and microbial characteristics in two-stage membrane bioreactor applied to partially stabilized leachate.

A two-stage membrane bioreactor system was applied to the treatment of partially stabilized leachate from solid waste landfill in Thailand. In the system, an anoxic tank with incline tube for biomass separation from re-circulated sludge is followed by a second-stage aerobic tank in which a direct submerged hollow-fiber membrane module is used for solid-liquid separation. During steady operation of 200 days, BOD, COD, NH3 and TKN removals were found to be 99.6, 68, 89 and 86% respectively. Determination of nitrogen transforming bacteria by fluorescent in-situ hybridization technique revealed a slightly higher percentage of nitrifying bacteria in the aerobic tank and a higher percentage of denitrifying bacteria in the anoxic tank respectively. Anammox-like bacteria were also detected at relatively high percentage.

Leachate treatment and greenhouse gas emission in subsurface horizontal flow constructed wetland.

Organic and nitrogen removal efficiencies in subsurface horizontal flow wetland system (HSF) with cattail (Typha augustifolia) treating young and partially stabilized solid waste leachate were investigated. Hydraulic loading rate (HLR) in the system was varied at 0.01, 0.028 and 0.056 m(3)/m(2) d which is equivalent to hydraulic retention time (HRT) of 28, 10 and 5 d. Average BOD removals in the system were 98% and 71% when applied to young and partially stabilized leachate at HLR of 0.01 m(3)/m(2) d. In term of total kjeldahl nitrogen, average removal efficiencies were 43% and 46%. High nitrogen in the stabilized leachate adversely affected the treatment performance and vegetation in the system. Nitrogen transforming bacteria were found varied along the treatment pathway. Methane emission rate was found to be highest at the inlet zone during young leachate treatment at 79-712 mg/m(2) d whereas CO2 emission ranged from 26-3266 mg/m(2) d. The emission of N2O was not detected.

Photosynthetic bacteria pond system with infra-red transmitting filter for the treatment and recovery of organic carbon from industrial wastewater.

A photosynthetic bacteria pond system was applied to the treatment of food industrial wastewater and recovery of carbon in the form of purple non-sulphur bacterial (PnSB) cell. The effect of infra-red transmitting filter on the selection of microbial groups in the system was investigated. It was found that more than 90% of organic removal could be achieved when the system was operated at HRT of 3 to 10 days, even though some fluctuations were observed at lower HRT. Infra-red transmitting filter could suppress the growth of microalgae in the system and allow the purple non-sulphur to grow in the system. Nevertheless, they could be outgrown by sulphate-reducing bacteria at higher organic loading rates. The growth of purple sulphur bacteria associated with sulphate reducing bacteria was also observed. ORP is a crucial operating factor to control the system under micro-anaerobic conditions which is preferred to the growth of purple non-sulphur bacteria.

Municipal solid waste management in Thailand and disposal emission inventory.

The increasing municipal solid waste (MSW) generation along with the high fraction of organic waste and a common disposal of open dumping is the current scenario in many areas in Thailand. As a response to this problem, the country's Pollution Control Department (PCD) aims to reduce the MSW generation rate to less than 1 kg/capita/day, increase the collection efficiency, and improve the recovery of recyclables. For many years, more than 60% of the solid waste disposal system in Thailand has been carried out by open dumping. According to the survey conducted by this study, in 2004 there were 425 disposal sites (95 landfills; 330 open dumps) in Thailand and an estimated methane emission of 115.4 Gg/year was generated based on this practice. It has been estimated that the anticipated methane emission in Thailand will rise from 115.4 Gg/year to 118.5 Gg/year if the largest open dumpsites in provinces with no existing landfill are upgraded to sanitary landfill; and it will increase to 193.5 Gg/year if the existing sanitary landfill is upgraded to integrated waste management facilities. Moreover, Bangkok metropolitan have the highest methane emission (54.83 Gg/year) among all the regions in Thailand. The methane emission forecast of 339 Gg/year by 2020 (based on LandGEM methodology) provides a stimulus to create a comprehensive plan to capture and utilize methane as an energy source.

Piggery wastewater treatment in a tropical climate: biological and chemical treatment options.

A novel biological treatment system was developed for the treatment of piggery wastewater under tropical conditions. It consisted of three consecutive sponge-based floating biofilters. The Upflow Anaerobic/Anoxic/Aerobic Floating Filter (UA3FF) system was shown to be effective with carbonaceous and, particularly, nitrogenous matter. The rationale for the processes occurring in anoxic-aerobic reactors was based on the concept of nitritation-denitritation rather than nitrification-denitrification. The N-related microbial communities manipulated by changing DO concentration and hydraulic retention time were able to effect a considerable increase in the total and specific N-removal (70% and 0.6 kg N m(-3) filter media per day, respectively) as compared to data reported elsewhere. Fluorescence In Situ Hybridization and Polymerase Chain Reaction amplification of ammonia monooxygenase (amoA) gene were used to study interrelationships between N-related microbial groups in the system. Microbiological data was interpreted in terms of operational behavior and performance of the reactors. The N-removal efficiency of the biological UA3FF system was compared with a combined biological/physicochemical system based on (a) biological anaerobic pretreatment followed by (b) a chemical precipitation (CP) and (c) an air stripping. Both systems were scrutinized as to operational advantages and costs. The treatment options could produce effluent of a high quality (202 mg COD l(-1), 126 total-N l(-1) and 89 mg COD l(-1) 48 total-N l(-1) in the biological and combined biological/physico-chemical treatment options, respectively) amenable for the subsequent treatment at the municipal facilities. However, the UA3FF biological treatment system was superior to the combined system by a factor of 20 as far as costs are concerned.

Solid waste characteristics and their relationship to gas production in tropical landfill.

Solid waste characteristics and landfill gas emission rate in tropical landfill was investigated in this study. The experiment was conducted at a pilot landfill cell in Thailand where fresh and two-year-old wastes in the cell were characterized at various depths of 1.5, 3, 4.5 and 6 m. Incoming solid wastes to the landfill were mainly composed of plastic and foam (24.05%). Other major components were food wastes (16.8%) and paper (13.3%). The determination of material components in disposed wastes has shown that the major identifiable components in the wastes were plastic and foam which are resistant to biodegradation. The density of solid waste increased along the depth of the landfill from 240 kg m(-3) at the top to 1,260 kg m(-3) at the bottom. Reduction of volatile solids content in waste samples along the depth of landfill suggests that biodegradation of solid waste has taken place to a greater extent at the bottom of the landfill. Gas production rates obtained from anaerobic batch experiment were in agreement with field measurements showing that the rates increased along the depth of the landfill cell. They were found in range between 0.05 and 0.89 l kg(-1) volatile solids day(-1). Average emission rate of methane through the final cover soil layer was estimated as 23.95 g(-2)day(-1) and 1.17 g(-2)day(-1) during the dry and rainy seasons, respectively.

Effects of ozonation process on lignin-derived compounds in pulp and paper mill effluents.

The effect of ozonation process on pulp and paper mill effluents was investigated. The objectives were to: (1) identify various compounds in wastewater from a pulp and paper mill, (2) evaluate decolorization and organic removal efficiency by conventional bubble reactor and (3) evaluate the biodegradability at various progressive stages of ozonation. The qualitative GC/MS analyses were performed before and after the biological treatment and ozonation process. Two groups of compounds were observed in this wastewater: lignin-derived compounds and aliphatic compounds used in the pulp and paper production process (i.e. n-alkanes, fatty alcohols, fatty acid and ester). Treatment efficiency was measured by decolorization and TOC removal rates. Additionally, the utilization coefficient (k) and BOD/COD ratio were determined to observe the biodegradability of ozonized effluents. The results indicated that after 45 min, the ozonation of effluents yielded almost colorless effluent with over 90% decolorization efficiency and with corresponding ozone capacity rate of 20.0 mg O(3)L(-1). This decolorization was not always accompanied by the mineralization of the organic matters therefore ozonation was not related to TOC removal rates. The BOD/COD ratio increased from 0.10 to a maximum value of 0.32 with ozone flow rate (O/F) of 4.0 L min(-1). It was confirmed by the utilization coefficient as first order BOD equation, the magnitude k value increased from 0.21 day(-1) to maximum value of 0.47 day(-1) as the ozonation time was raised to 60 min with O/F 4.0 L min(-1).

Enhancement of oxygen transfer and nitrogen removal in a membrane separation bioreactor for domestic wastewater treatment.

Biological nitrogen removal in a membrane separation bioreactor developed for on-site domestic wastewater treatment was investigated. The bioreactor employed hollow fiber membrane modules for solid-liquid separation so that the biomass could be completely retained within the system. Intermittent aeration was supplied with 90 minutes on and off cycle to achieve nitrification and denitrification reaction for nitrogen removal. High COD and nitrogen removal of more than 90% were achieved under a moderate temperature of 25 degrees C. As the temperature was stepwise decreased from 25 to 5 degrees C, COD removal in the system could be constantly maintained while nitrogen removal was deteriorated. Nevertheless, increasing aeration supply could enhance nitrification at low temperature with benefit from complete retention of nitrifying bacteria within the system by membrane separation. At low operating temperature range of 5 degrees C, nitrogen removal could be recovered to more than 85%. A mathematical model considering diffusion resistance of limiting substrate into the bio-particle is applied to describe nitrogen removal in a membrane separation bioreactor. The simulation suggested that limitation of the oxygen supply was the major cause of inhibition of nitrification during temperature decrease. Nevertheless, increasing aeration could promote oxygen diffusion into the bio-particle. Sufficient oxygen was supplied to the nitrifying bacteria and the nitrification could proceed. In the membrane separation bioreactor, biomass concentration under low temperature operation was allowed to increase by 2-3 times of that of moderate temperature to compensate for the loss of bacterial activities so that the temperature effect was masked.

Particle and microorganism removal in floating plastic media coupled with microfiltration membrane for surface water treatment.

Floating plastic media followed by hollow fiber microfiltration membrane was applied for surface water treatment. The performance of the system in terms of particle and microorganisms was investigated. The floating filter was examined at different filtration rates of 5, 10 and 15 m3/m2 x h. Treated water was then fed into a microfiltration unit where different filtration rates were examined at 0.6, 1.0 and 1.4 m3/m2 x d. It was found that polyaluminum chloride was the best coagulant for the removal of particle, algae and coliform bacteria. Average turbidity in treated water from the floating plastic media filter was 3.3, 12.2 and 15.5 NTU for raw water of 80 NTU and 12.9, 11.7 and 31.2 NTU for raw water of 160 NTU after 6 hours at the filtration rates of 5, 10 and 15 m3/m2 x h, respectively. The microfiltration unit could further reduce the turbidity to 0.2-0.5 NTU with low transmembrane pressure development of 0.3-3.7 kPa. Microfiltration membrane could retain most of algae and coliform bacteria remaining in the effluent from the pretreatment unit. It was found that at higher turbidity, algae and coliform bacteria removal efficiencies were achieved at lower filtration rate of the system of 5 m3/m2 x h whereas a higher filtration rate of 15 m3/m2 x h yielded better coliphage removal.

Effect of moisture content on fed batch composting reactor of vegetable and fruit wastes.

Vegetable and fruit wastes mixed with sawdust were composted in a laboratory scale reactor by controlling the waste feeding rate at 21 kg m(-3) day(-1) and aeration rate at 10.6 l m(-3) min(-1). The effects of initial moisture content on organic matter degradation and process performance of fed batch composting were investigated. The absolute amount of removal, removal percentage, and removal rate of dry mass obtained were substantially different among the initial moisture contents. The rapid rise of moisture content and the lowest absolute amount of removal observed were achieved in the 50% condition. The initial moisture content yielding the largest absolute amount of removal in both feeding and curing stage was 30% whereas the removal percentage and rate constant of waste decomposition were highest in the 50% condition. Examined by traditional soil physics method, the moisture content at 50-55% was suitable for satisfying the degree of free air space (65-70%) of compost during the fed batch composting. Most degradable organic matter was mainly consumed in the feeding stage as indicated by a higher removal rate of dry mass in all cases. It is recommended that the initial moisture content of 30% and mode of aeration and agitation should be adopted for achieving practical fed batch composting of vegetable and fruit wastes. The study also demonstrated that the composting kinetics of vegetable and fruit wastes mixed with sawdust can be described by a first order model.

Simultaneous organic stabilization and nitrogen removal in multi-stage biodrum system.

This paper presents the performance of a multi-stage biodrum system applied to domestic wastewater treatment. The organic stabilization and nitrogen removal efficiency in the system was investigated at different hydraulic retention times (HRT) of 12, 6 and 3 hours. The rotational speed of the biodrum was examined at 2,4 and 8 rpm. Average organic removal efficiencies in the system at different HRTs of 12, 6 and 3 hours were 96.3, 94.4 and 90.9%. Simultaneously, average nitrogen removal efficiencies were 91.5, 90.6 and 81.0%. The effect of rotational speed on nitrogen removal efficiencies in the system was clearly observed at a low HRT of 3 hours. The experimental results suggested that optimum HRT in the system was 6 hours. Moreover, they revealed that nitrogen removal efficiencies in the reactors operated at different rotational speed were in the same degree when considering the effluent nitrogen concentration. However, the reactors operated at lower rotational speed needed to employ higher numbers of biodrums (4 stages) than the others with higher rotational speed (3 and 2 stages at 4 and 8 rpm.) in order to achieve similar effluent qualities. At a rotational speed of 2 rpm, maximum nitrogen removal rate was found to be 0.2 kg/m3/d.

Development of floating plastic media filtration system for water treatment and wastewater reuse.

Floating plastic media coupled with sand filtration system was applied for treating surface water and secondary effluent from municipal sewage treatment plant. The system employed floating plastic media for the removal of suspended solids in surface water and precipitated phosphorus from secondary effluent of sewage treatment plant. Sand filtration was then used to remove further the suspended solids. For the purposes of wastewater reuse, a zeolite layer was used instead of sand filter to absorb ammonium nitrogen. Application of system for surface water treatment suggested appropriate filtration rate of 5 m3/m2 h. Polyaluminum chloride was found to be the best coagulant with an appropriate plastic and sand bed depth of 40 cm. The system could produce average effluent turbidity and suspended solids of 0.71 NTU and 0.94 mg/L respectively. Average turbidity and suspended solids removal efficiencies were 96.26% and 95.48% with low headloss development of 40.4 cm at the end of 6 h operation period. When applying 1.50 m. floating plastic media bed for the treatment of synthetic raw water, short and long-term turbidity removal efficiencies were 96.79-97.72% and 81.81-94.61% for raw water containing turbidity of 20 and 40 NTU. It could produce the effluent with turbidity less than 5NTU while having less than 1.0 m. headloss. The system was also applied for the secondary effluent treatment. An optimum filtration rate of 5 m3/m2 h was obtained when using plastic and sand bed depth of 60 and 20cm under direct filtration mode. Average turbidity removal was 60.3% and 59.6% after 6 and 48 h of operation. It was also found that 1 m3/m2 h filtration rate and 50:30 cm of plastic:zeolite bed could be used to achieve both ammonium nitrogen and phosphate removal. Suspended solids, turbidity, BOD5, NH4+, and PO4(3-) removal efficiencies were 91.9, 94.6, 95.4, 97.3, and 99.5% respectively after 24 h. As a result, the effluent from the system had average NH4+ and PO4(3-) of 0.5 mg N/L and 0.02 mg P/L.

Opisthorchiatic solitary intrahepatic cyst.

Eleven patients were documented as having opisthorchiatic solitary intrahepatic cyst by roentgenography--P.T.C., identification of opisthorchis ova in the bile during P.T.C. and operation. This clinical entity should be differentiated from other forms of intrahepatic cyst. We believe that it is an acquired form. The formation of opisthorchiatic solitary intrahepatic cyst is related to lower biliary tract obstruction and high pressure in the biliary system. Fever, pain in the right upper quadrant and jaundice are the major manifestations of opisthorchiatic solitary intrahepatic cyst. Surgical intervention is the therapeutic method.