Wastewater treatment in tsunami affected areas of Thailand by constructed wetlands.

The tsunami of December 2004 destroyed infrastructure in many coastal areas in South-East Asia. In January 2005, the Danish Government gave a tsunami relief grant to Thailand to re-establish the wastewater management services in some of the areas affected by the tsunami. This paper describes the systems which have been built at three locations: (a) Baan Pru Teau: A newly-built township for tsunami victims which was constructed with the contribution of the Thai Red Cross. Conventional septic tanks were installed for the treatment of blackwater from each household and its effluent and grey water (40 m3/day) are collected and treated at a 220 m2 subsurface flow constructed wetland. (b) Koh Phi Phi Don island: A wastewater collection system for the main business and hotel area of the island, a pumping station and a pressure pipe to the treatment facility, a multi-stage constructed wetland system and a system for reuse of treated wastewater. The constructed wetland system (capacity 400 m3/day) consists of vertical flow, horizontal subsurface flow, free water surface flow and pond units. Because the treatment plant is surrounded by resorts, restaurants and shops, the constructed wetland systems are designed with terrains as scenic landscaping. (c) Patong: A 5,000 m2 constructed wetland system has been established to treat polluted water from drainage canals which collect overflow from septic tanks and grey water from residential areas. It is envisaged that these three systems will serve as prototype demonstration systems for appropriate wastewater management in Thailand and other tropical countries.     

Micro-scale energy dissipation mechanisms during dynamic fracture in natural polyphase ceramic blocks

The dynamic fracture of natural polyphase ceramic (granite) blocks by high-speed impact at 207 m/s, 420 m/s and 537 m/s has been investigated. An electromagnetic railgun was used as the launch system. Results reveal that the number of fragments increases substantially, and the dominant length scale in their probability distributions decreases, as the impact energy is increased. Micro-scale studies of the fracture surfaces reveals evidence of localized temperatures in excess of 2000 K brought on by frictional melting via fracturing and slip along grain boundaries in orthoclase and plagioclase, and via transgranular fracture (micro-cracking) in quartz. The formation of SiO₂- and TiO₂-rich spheroids on fracture surfaces indicates that temperatures in excess of 3500 K are reached during fracture.     

An integrated electro-chemical and natural treatment system for industrial water pollution control.

Experiments were conducted to test the feasibility of applying an integrated electro-chemical (EC) and natural treatment system for treatment of some industrial wastewaters. The EC process was found to be very effective in removing lead, a model heavy metal from some wastewaters. Within 20 minutes of operation time, 5 to 10 A of electric current and specific surface area of electrode of 46.51 m2/m3, the lead concentrations in the wastewaters were reduced from 35-100 mg/l to less than 1 mg/l. Based on a kinetic model developed from the experimental data, the important parameters for the EC process were found to be electric current, specific surface area of electrode, and operation time. From scanning electron microscopic and X-ray diffractometric (XRD) analysis, the EC sludge samples were found to compose mainly of maghemite (Fe2O3), magnetite (Fe3O4), and laurionite (PbClOH), suitable for disposal to secure landfills. Two pilot-scale constructed wetlands (CW) in series, a model natural treatment system, were employed to treat wastewaters of an industrial estate in Thailand. At organic loading rates of 57-140 kg BOD/hectare-year, these constructed wetlands were able to reduce BOD from 90 to 4 mg/l, while suspended solids, total nitrogen and total phosphorus were reduced from 100 to 10 mg/l, 24 to 4.6 mg/l and 7 to 1.5 mg/l, respectively, during the summer season. These results demonstrated technical feasibility of CW in removing organic and other pollutants contained in this industrial wastewater.     

A simplified spectrophotometric method for the determination of inulin in Jerusalem artichoke (<Emphasis Type="Italic">Helianthus tuberosus</Emphasis> L.) tubers

A simple spectrophotometric method was developed for the analysis of inulin in Jerusalem artichoke tubers. The inulin was extracted from the artichoke tuber samples using accelerated solvent extraction method, before subsequent hydrolysis in acid condition. The hydrolysates were then analyzed for fructose using spectrophotometry. The spectrophotometric method is based on oxidation of fructose by periodate and evaluation of the remaining periodate by measuring the absorbance at 350 nm of the tri-iodide complex formed, upon addition of potassium iodide. The optimum conditions for the detection of fructose were 0.1 mmol L⁻¹ periodate and 1.5 mmol L⁻¹ potassium iodide at pH 6.0. The proposed method was validated for its analytical performance parameters including accuracy, precision, and recovery. The method was applied to the determination of inulin in ten varieties of Jerusalem artichoke grown in the northeastern part of Thailand. The inulin content in the samples was found to be in the range of 63–75.5% dry weight, and the degree of polymerization was in the range of 14–20. The inulin contents obtained from the proposed spectrophotometry were not significantly different (p = 0.05) from those obtained from high-performance anion-exchange chromatography coupled with pulsed amperometric detection. The results indicated that the present spectrophotometric method can be used as an alternative to chromatographic analysis for the determination of inulin in plant samples.     

Comparison of Rapid Methods for Detection of Giardia spp. and Cryptosporidium spp. (Oo)cysts Using Transportable Instrumentation in a Field Deployment

Reliable, sensitive, quantitative, and mobile rapid screening methods for pathogenic organisms are not yet readily available, but would provide a great benefit to humanitarian intervention units in disaster situations. We compared three different methods (immunofluorescent microscopy, IFM; flow cytometry, FCM; polymerase chain reaction, PCR) for the rapid and quantitative detection of Giardia lamblia and Cryptosporidium parvum (oo)cysts in a field campaign. For this we deployed our mobile instrumentation and sampled canal water and vegetables during a 2 week field study in Thailand. For purification and concentrations of (oo)cysts, we used filtration and immunomagnetic separation. We were able to detect considerably high oo(cysts) concentrations (ranges: 15-855 and 0-240 oo(cysts)/liter for Giardia and Cryptosporidium, respectively) in 85 to 300 min, with FCM being fastest, followed by PCR, and IFM being slowest due to the long analysis time per sample. FCM and IFM performed consistently well, whereas PCR reactions often failed. The recovery, established by FCM, was around 30% for Giardia and 13% for Cryptosporidium (oo)cysts. It was possible to track (oo)cysts from the wastewater further downstream to irrigation waters and confirm contamination of salads and water vegetables. We believe that rapid detection, in particular FCM-based methods, can substantially help in disaster management and outbreak prevention.     

A Water Model for Water and Environmental Management at Mae Moh Mine Area in Thailand

It is revealed that the water quality in Mae Moh Reservoir, Thailand, has been deteriorated by lignite mine drainage and power station effluent. This study aims to manipulate water quantity and quality to reduce environmental impacts in Mae Moh area through a model for water management. The model was constructed on the basis of materials balance to predict water flow, which includes concentrations of TDS and SO ^2– ₄. Data collected during 1996–2000 were used. Model validation showed that the mean of predicted and actual values of TDS and SO ^2– ₄ load were significantly similar at 95% confidence limit. The test result is acceptable and the water model can be used as a tool for water system management in the area. In 2006, Mae Moh mine excess water will be discharged at 10.76 Mm³, with a pH of 7.3, TDS and SO ^2– ₄ concentrations of 2,547 and 1,803 mg/l, respectively. Mae Moh power station effluent will be 14.59 Mm³, with pH of 7.1, TDS and SO ^2– ₄ concentrations of 610 and 358 mg/l, respectively. Predicted results showed that the outflow of Mae Moh Reservoir will be 83.67 Mm³ and the concentrations of TDS and SO ^2– ₄ will be as high as 1,501 and 822 mg/l, respectively. Mine excess water management measures are recommended according to the following strategy. All mine excess water should be stored during dry season. During wet season, 50% of the excess water should be stored and the remaining treated at 90% of TDS removal before being discharged. The end result would be a significant improvement in water quality in the Mae Moh Reservoir over the 4-year period to 2010. Pollutants in terms of TDS would be reduced by 35% from 1,501 mg/l in the beginning of 2006 to 975 mg/l at the end of 2009.     

Nitrogen removal in recirculated duckweed ponds system.

Duckweed-based ponds (DWBPs) have the potential for nitrogen (N) removal from wastewater; however, operational problems such as duckweed die-off regularly occur. In this study, effluent recirculation was applied to the DWBPs to solve the above problem as well as to investigate N removal mechanisms. Two pilot scale recirculated DWBPs were employed to treat municipal wastewater. The average removal efficiencies for TN, TKN and NH4-N were 75%, 89% and 92%, respectively at TN loading of 1.3 g/m2.d and were 73%, 74% and 76%, respectively at TN loading of 3.3 g/m2.d. The effluent of the system under both operational conditions had stable quality and met the effluent standard. Duckweed die-off was not observed during the study, which proves the system stability and effluent recirculation which is thought to be a reason. N-mass balance revealed that nitrification-denitrification and duckweed uptake play major roles in these recirculated DWBPs. The rates of nitrification-denitrification were increased as TN loading was higher, which might be an influence from an abundance of N and a suitable condition. The rates of N uptake by duckweed were found similar and did not depend on the higher TN loading applied, as the duckweed has limited capacity to assimilate it.     

Thermodynamics of the encapsulation by cyclodextrins

Molecular encapsulation on a molecular basis can be performed by cyclodextrins. The inclusion of organic molecules into the interior changes the properties of these molecules, which may be used for a broad variety of applications. The affinity of guest molecules for the cavities of various cyclodextrins depends on the stereochemistry and on the interaction forces of the molecules involved. Calculations of the thermodynamic parameters show that the reaction entropy is highly important for the inclusion reaction. Completely different reaction mechanisms are observed for various types of cyclodextrins as some of these reactions show enthalpy–entropy compensation. Others are supported by the reaction entropy or are even entropically controlled. Protonation and deprotonation reactions contribute significantly to the inclusion reaction, as first of all the solubility of the compounds in water is strongly influenced by the acidity of the solution, and, moreover, all tautomeric forms of the compounds show different affinities to various cyclodextrins. Copyright © 2006 Society of Chemical Industry     

Integrated faecal sludge treatment and recycling through constructed wetlands and sunflower plant irrigation.

Faecal sludge (FS) from the on-site sanitation systems is a nutrient-rich source but can contain high concentrations of toxic metals and chemicals and infectious micro-organisms. The study employed 3 vertical-flow CW units, each with a dimension of 5 x 5 x 0.65 m (width x length x media depth) and planted with cattails (Typha augustifolia). At the solid loading rate of 250 kg total solids (TS)/m(2).yr and a 6-day percolate impoundment, the CW system could achieve chemical oxygen demand (COD), TS and total Kjeldahl nitrogen (TKN) removal efficiencies in the range of 80-96%. A solid layer of about 80 cm was found accumulated on the CW bed surface after operating the CW units for 7 years, but no clogging problem has been observed. The CW percolate was applied to 16 irrigation sunflower plant (Helianthus annuus) plots, each with a dimension of 4.5 x 4.5 m (width x length). In the study, tap water was mixed with 20%, 80% and 100% of the CW percolate at the application rate of 7.5 mm/day. Based on a 1-year data in which 3 crops of plantation were experimented, the contents of Zn, Mn and Cu in soil of the experimental plots were found to increase with increase in CW percolate ratios. In a plot with 100% of CW percolate irrigation, the maximum Zn, Mn and Cu concentrations of 5.0, 12.3 and 2.5 mg/kg, respectively, were detected in the percolate-fed soil, whereas no accumulation of heavy metals in the plant tissues (i.e. leaves, stems and flowers) of the sunflower were detected. The highest plant biomass yield and oil content of 1000 kg/ha and 35%, respectively, were obtained from the plots fed with 20% or 50% of the CW percolate.     

Influence of sand layer depth and percolate impounding regime on nitrogen transformation in vertical-flow constructed wetlands treating faecal sludge

Four laboratory-scale units of vertical-flow constructed wetlands (VFCW) were fed once a week with faecal sludge (FS) at a constant solids loading rate (SLR) of 250 kg TS/(m².year) (equivalent to 260-300 g N/(m².week)) for a period of 12 weeks to study: i) the nitrification and denitrification potential of the sand layer of VFCWs and ii) the effect of percolate impounding regime (permanent or batch-impounding) on nitrogen transformation. The TN content of raw FS was characterised by 65% org-N, 34% NH₄-N and 1% NO_x-N. After FS application and a six-day impounding period, 8-13% TN were recovered in the percolate exhibiting the following composition: 70-80% NH₄-N, 25-30% org-N and <1% NO_x-N. A large fraction of the influent organic N (55%) was filtered in the bed and 24-29% of initial NH₄-N were lost due to nitrification and volatilisation. In permanent impounding systems, 8-11% TN were recovered in the percolate versus 13% in batch-operated beds. N loss was increased with sand layer depth (20-40 cm) under permanent impounding regimes.