Maung Thein Myint

Enhancing anaerobic hydrolysis of cattle manure in leachbed reactors

In this study, it is hypothesized that anaerobic hydrolysis of organic solid wastes (OSWs) in leachbed reactors can be enhanced by two approaches: (1) by increasing the porosity of the leachbed; and (2) by seeding the bed with brown-rot fungi or anaerobically digested residues. The hypothesis is verified using cattle manure as a model OSW and pistachios-half-shell as an inert additive to increase the porosity of the leachbed. The enhancement was quantified in terms of volatile fatty acid (VFA) generation and soluble COD generation. Results of this study showed that 15% more VFAs and 8% more soluble COD can be obtained at higher bed porosities and with brown-rot fungi or digested residues as the seed. Compared to a leachbed without any recirculation, porosity enhancement, nor seed addition, the VFA yield (g VFA/g manure) in a leachbed with pistachios-half-shell as porosity enhancers was 193% higher; that in a leachbed with leachate recirculation (of 4 L/day), pistachios-half-shell as porosity enhancers, and brown-rot fungi or digested sludge as seed was 230% higher.

Use of drinking water treatment solids for arsenate removal from desalination concentrate

Desalination of impaired water can be hindered by the limited options for concentrate disposal. Selective removal of specific contaminants using inexpensive adsorbents is an attractive option to address the challenges of concentrate management. In this study, two types of ferric-based drinking water treatment solids (DWTS) were examined for arsenate removal from reverse osmosis concentrate during continuous-flow once-through column experiments. Arsenate sorption was investigated under different operating conditions including pH, arsenate concentration, hydraulic retention time, loading rate, temperature, and moisture content of the DWTS. Arsenate removal by the DWTS was affected primarily by surface complexation, electrostatic interactions, and arsenate speciation. Results indicated that arsenate sorption was highly dependent on initial pH and initial arsenate concentration. Acidic conditions enhanced arsenate sorption as a result of weaker electrostatic repulsion between predominantly monovalent H2AsO4(-) and negatively charged particles in the DWTS. High initial arsenate concentration increased the driving force for arsenate sorption to the DWTS surface. Tests revealed that the potential risks associated with the use of DWTS include the leaching of organic contaminants and ammonia, which can be alleviated by using wet DWTS or discarding the initially treated effluent that contains high organic concentration.

Complete sustainability in electrodialysis reversal desalination: reusing tertiary-treated municipal wastewater as feed in the concentrate stream and electrodes rinsing water

abstract Electrodialysis reversal (EDR) has been innovative based on unplanned indirect potable water reuse to replace the same amount of raw water withdrawn from brackish (sea) water source and conserving 15–20% of freshwater by reusing tertiary-treated municipal wastewater (TTMWW) as feed in the concentrate and electrode stream while brackish groundwater (sea water) remains feed into dilute stream. By substituting TTMWW, our analysis shows the resulting total dissolved solid (TDS) concentration in the waste stream lower than that in the original source of brackish groundwater (sea water) which fed into dilute stream. The waste from EDR system with TTMWW as feed in concentrate and electrode streams can be recharged back into groundwater (sea water) source which do not add the TDS concentration. In fact, it reduces the TDS concentration by dilution. New significant findings are: (1) 17,500 m3/d of freshwater could be saved with the data from 1990; the saving would be increased in 2011 and much more in fut...

Electrodialysis reversal desalination: monographs for the design parameters

Abstract Electrodialysis reversal (EDR) is known for its excellence to desalt Ca2+ and dominated brackish groundwater with a higher water recovery rate, an elevated silt density index (SDI 6-12), potential for biofouling, hard-to-treat, high hardness, and lower salinity feed waters with the ranges of 200–5000 mg/L TDS. The power index is the only currently available design and evaluating parameter for the EDR process; however, power index is only valid for the same total dissolved solid (TDS) concentrations of feed and product water. Since, ED/EDR is capable of treating a variable source of water quality while producing a consistent finished water quality, comprehensive design and evaluating parameters are required, identified and proposed in this study. The quantities of the design parameters were developed from 52 sets of literature experimental data that have 10 different types of feed water characteristics. Another one set of literature experimental data was used to validate the values of developed pa...

Electrodialysis reversal desalination: optimal voltage application rate, linear velocity, and mean ion residence time for maximal ion removal rate

AbstractOptimal voltage application rate, linear velocity, and mean ion residence time (MIRTd) in dilute stream were searched for electrodialysis reversal desalination by using two different feed waters containing TDS 3330 and 7190 mg/L NaCl. Two sets of literature data were used in the analyses. First, the relation among demineralization degree, voltage application rate, and MIRTd were derived from theory. Then, the findings were analyzed from the first set of literature data and validated with the second set of data. The analyses show that the maximal demineralization degree does not appear at the highest voltage application alone and that demineralization degree increases with the increasing voltage application rate to a certain critical value only. The maximal demineralization degree occurs at the combination of lower voltage application and longer MIRTd or vice versa. Data show the maximal demineralization degree does not always present the maximal ion removal rate per effective area of cell pairs pe...

Energy usage and carbon dioxide emission saving in desalination by using desalination concentrate and wastes in microalgae production

AbstractEnergy usage and CO2 emission between traditional electrodialysis reversal (EDR) and innovative EDR desalinations were compared. The difference between traditional and innovative EDR desalination depended on which concentrate treatment was employed. Traditional EDR desalination consists of electrodialysis as concentrate treatment, while innovative EDR desalination consists of Dunaliella salina production as concentrate treatment. Microalgae species D. salina and Arthrospira (Spirulina) platensis were cultured in used bottles (3.7 L) as reactors and using desalination concentrate and supernatant from anaerobic digested sludge (SADS) as growth medium and nutrients. D. salina was grown in reactors D1, D2, D3, and D4. Spirulina platensis was in S1, S2, S3, and S4. SADS was supplied to reactors D1, D2, S1, and S2 as nutrient. Bold’s Basal Medium was supplied to reactors D3 and D4 while F2 was supplied to reactors S3 and S4 as nutrient. Conductivity of desalination concentrates used in reactors D1 and D...

A generic stoichiometric equation for microalgae-microorganism nexus by using clarified domestic wastewater as growth medium

AbstractStoichiometric equations for microalgae–microorganism nexus culture were established by using 18 sets of experimental data from the literature where clarified domestic wastewater (CDWW) was used as a growth media. The best correlations between observed and calculated coefficients in the equations were 0.908, 0.878, 0.838, and 0.849 for reactors R1, R2, R3, and the sum of three reactors, respectively. Then, each stoichiometric equation was generalized to quantitatively describe the reactions in each set of data for 18 different experimental conditions. By analysis, the most and second most sensitive limiting parameters were identified from the 18 stoichiometric equations. The formulas and equations were further upgraded to a generic form for a general organic growth medium (CaHbOcNdPf). Microalgae–microorganism nexus was established by using the developed coefficients to depict the limited and balanced reactions. The study showed that nitrogen and phosphorus are required as additives in CDWW in ord...

Microalgal process for treatment of high conductivity concentrates from inland desalination

AbstractDesalination concentrate contains high levels of dissolved ions such as alkalinity, sulfate, and synthetic chemicals. Microalgal species that have ability to grow in the presence of these ions can be used to treat concentrates. A natural indigenous microalgal consortium originally grown in the concentrate of an evaporation pond was selected, cultured, and seeded in the growth medium for treatment of concentrates. Fed-batch experiments were performed with five different conductivities of concentrates in five reactors, with duplicates. Supernatants or leachates from anaerobic digested sludges were supplied as nutrients. Energy was supplied by sunlight during regularly scheduled office hours. Artificial light was supplied as energy during the weekend and all holiday hours. Environmental air was supplied as carbon during the office hours, weekend, and holidays. Water quality from treated concentrate in reactor R1 at 20 d of treatment was sufficiently pure to be given to sheep. Overall mass conductivit...