Intake Seawater Research Articles

Chlorination Byproducts in Drinking Water Produced from Thermal Desalination in United Arab Emirates

Oil activities in the Arabian Gulf can potentially affect the quality of the intake water available for coastal desalination plants. This paper addresses such situation by investigating the quality of intake water and desalinated water produced by a desalination plant located near a coastal industrial complex in United Arab Emirates (UAE). Analyses of the organic compounds on the intake seawater reported non-detected levels in most samples for the three tested organic groups; namely Polyaromatic Hydrocarbons (PAHs), Phenols, and Polychlorinated Biphenyls (PCBs). Trihalomethanes (THMs) and Haloacetic Acids (HAAs) were also tracked in the intake sea water, throughout the desalination processes, and in the final produced drinking water, to evaluate the undertaken pre- and post chlorination practices. The levels of considered Chlorination Byproducts (CBPs) were mostly found below the permissible international limits with few exceptions showing tangible levels of bromoform in the intake seawater and in the final produced drinking water as well. Lab-controlled experiments on the final produced distillate showed little contribution of its blending with small percentage of seawater upon the formation of trihalomethane and in particular, bromoform. Such results indicate that the organic precursors originated in the seawater are responsible for bromoform formation in the final distillate.

Brine entrainment in multistage flash desalination

Brine entrainment in the multistage flash desalination depends on the stage temperature. In the once through and the brine circulation systems, brine entrainment is high in the low temperature stages. In the brine circulation system and during winter operation, decrease in the feed seawater temperature requires operation of the cooling seawater recycle pump. This is to control the intake seawater temperature. Adoption of this technique might not be the optimum choice. This is because of the short duration of the winter period. Also, preparation and maintenance of this large size pump might not be technically feasible and would come at very high cost. Failure to operate the cooling seawater pump results in large increase in the product salinity. Therefore, it is necessary to extract product water from the first stages to supply the makeup boiler water. In the once through system, there is no control on the feed seawater temperature. Therefore, the product salinity increases during winter operation. This would also call for product extraction from the high temperature stages. makeup water. Parametric analysis is presented for variations in the product salinity as a function of the feed seawater temperature.

Reverse osmosis on open intake seawater: pre-treatment strategy

Pre-treatment of seawater feeding reverse osmosis (RO) membranes is a key step in designing desalination plants. The pre-treatment process must be adapted to the seawater quality to be treated (wells, open intake, etc.), especially when treating surface seawater with highly variable quality. After a general presentation of different pretreatment options in relation to the seawater quality, this paper is focussing on two case studies, two open intake seawater pre-treatment upstream reverse osmosis desalination. The first site is located in the Gulf of Oman (Indian Ocean), the second in the Persian Gulf. The pre-treatment uses different technology strategies, conventional pretreatment (coagulation and direct filtration on dual media filters) and innovative technologies (high rate dissolved air flotation, ultrafiltration and microfiltration) according to the water quality. The parameters taken into account for the water quality characterisation are the suspended solids, turbidity, fouling tendency, organic matters and algae content. This paper presents the pre-treated water quality achieved by the two types of pre-treatment and discusses potential impacts on RO hydraulic performances.

Effects of thermal effluents from a power station on bacteria and heterotrophic nanoflagellates in coastal waters

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 229:1-10 (2002) - doi:10.3354/meps229001 Effects of thermal effluents from a power station on bacteria and heterotrophic nanoflagellates in coastal waters Dong H. Choi1, Jong S. Park1, Chung Y. Hwang1, Sung H. Huh2, Byung C. Cho1,* 1School of Earth and Environmental Sciences and Research Institute of Oceanography, Seoul National University, Seoul 151-742, Korea 2Department of Oceanography, Pukyong National University, Pusan 608-737, Korea *Corresponding author. E-mail: bccho@plaza.snu.ac.kr ABSTRACT: To investigate effects of thermal effluents from a coastal power station on bacteria and heterotrophic nanoflagellates (HNF) in adjacent coastal waters, surface distributions of bacteria and HNF and interrelations between microbial and environmental variables were studied in November 1998 and July, August and November 1999 near Hadong Power Station, Korea. In addition, manipulation experiments with treatments of high temperature (40°C; temperature in the cooling system of the power station) and additions of hypochlorite and dilution experiments of thermal effluents with intake seawaters were carried out. Water temperature in the discharge-channel was always 5 to 10°C higher than the ambient temperature, but bacterial production, HNF abundance and grazing rates on bacteria, as well as chlorophyll a concentrations, were always lower there and increased with distance from the power station. Manipulation experiments showed that addition of hypochlorite had much more deleterious effects on bacteria and HNF (95 to 98% inhibition of bacterial production and 25 to 45% decrease in HNF abundance at 0.13 ppm of residual chlorine) than high temperature (9 to 39% inhibition of bacterial production but no inhibition of HNF abundance at 40°C). Dilutions of thermal effluents from the outlet and condenser tube with intake seawater would bring <0.03 ppm of residual chlorine, but inhibitory effects of thermal effluents on bacterial production and HNF grazing activity (23 to 69% inhibition of bacterial production and 31 to 36% inhibition of HNF grazing) were shown, indicating inhibitory potential of chlorination by-products in the discharged water on coastal microbes. Analyses of horizontal distributions of microbial variables, manipulation and dilution experiments gave consistently similar results of inhibitory effects of thermal effluents on bacteria and HNF. Our work suggests that a microbial ecological approach is useful in estimating influences of thermal pollution on microbes in aquatic environments. KEY WORDS: Thermal effluents · Chlorination · Bacteria · Heterotrophic nanoflagellates Full text in pdf format NextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 229. Online publication date: March 20, 2002 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2002 Inter-Research.

Performance of parallel feed multiple effect evaporation system for seawater desalination

Performance analysis is presented for the parallel feed multiple effect evaporation system. Two operating modes are considered in the analysis, which includes the parallel and the parallel/cross flow systems. Analysis is performed as a function of the heating steam temperature, salinity of the intake seawater, and number of effects. Results are presented as a function of parameters controlling the unit product cost, which includes the specific heat transfer area, the thermal performance ratio, the conversion ratio, and the specific flow rate of the cooling water. Results indicate that better performance is obtained for the parallel/cross flow system. However, the parallel feed system has similar characteristics and simpler design and operation procedures. Performance of both systems is consistent with literature data. Comparison of the two parallel feed systems versus conventional multistage flash desalination and the forward feed multiple effect evaporation schemes show that the forward feed system has better performance characteristics than the other three systems.

A temperature-sensitive acoustic transmitter for remote monitoring of stomach temperature in aquatic endotherms

Abstract A temperature-sensitive acoustic transmitter was developed to record and store stomach temperature. :he equipment was used to quantifY meal sizes in captive animals and to monitor stomach temperature changes in captive animals as a result of intake offood, snow, ice and seawater. The equipment has also been used to time food ingestion in free-ranging animals. The transmitter consists of the electronic circuit, a thermal sensor, an electro-acoustic transducer, a battery and the encapsulation. The time between the transmitter pulses is a function ofthe surrounding temperature of the transmitter.

Mass mortality of Penaeus monodon larvae due to antibiotic-resistant Vibrio harveyi infection

The cause of mass mortality in Penaeus monodon larvae in a hatchery was investigated. Antibiotic-resistant Vibrio harveyi could be isolated from all the infected larvae. These bacteria were absent in healthy eggs and nauplii. Although the intake seawater had V. harveyi, these strains were sensitive to antibiotics. The results suggest that antibiotic-resistant V. harveyi had been colonising larval tanks. The isolates from moribund larvae showed much lower LD 50 values than isolates from natural seawater, thus indicating their higher virulence.

The thermal effects of cooling system of a thermal power plant on photosynthesis of marine phytoplankton

The activity of photosynthesis and the contents of chlorophylla and pheo-pigments were compared in the samples of the intake and effluent seawater of Owase-Mita Thermal Power Plant and in the seawater samples in the Yoshimi Bay before and after heat treatment. At Owase-Mita Thermal Power Plant, after passage of sea water through the cooling system chlorophylla content reduced to about a half and pheo-pigment content doubled in August with high temperature (25–27‡C), but the contents of chlorophylla and pheo-pigments changed little in January with low temperature (16‡C); whereas the depression of photosynthetic activity after passing through the cooling system was 71–77 % in August and 31–46 % in January. In the laboratory experiments, the heat treatment at 34–43‡C for 7–8 sec., which resulted in temperature rise of 7–8‡C, gave the decrease of chlorophylla and an increase of pheo-pigments in August temperature (26.5‡C), but a slight decrease of chlorophylla and a slight increase of pheo-pigments in November at the initial temperature of 19.2‡C, while in January and December the samples with low initial temperature (11.6 and 10.8‡C) showed almost no change in the content of pigments; the decrease in photosynthetic activity was 32 % in August sample,ca. 11 % in November sample,ca. 15% in January and almost no change in December. It is concluded that the photosynthetic carbon assimilation of marine phytoplankton is suppressed by passing through the cooling system of a thermal power plant even at lower water temperature in winter, while the content of chlorophylla is affected very little at a temperature below 20‡C.