WaterSubject

The emphasis placed on diffuse pollution under Article I of the Water Framework Directive (WFD) is of particular relevance to the problem of nonpoint urban surface water drainage. Although the Directive does not define diffuse pollution, it does specify within Articles II.3 (h) and Article II the need to identify and quantify diffuse sources, with Annex IV and VII requiring estimates and a programme of measures for monitoring and control of such diffuse sources within future River Basin Management Plans (RBMPs). The ... Read More

The Gaza Strip is a densely populated area. More than 1 200 000 inhabitants live in an area of only 365 km2. The environmental situation has deteriorated owing to the difficulties and constraints associated with the ongoing political situation in the region. Three wastewater treatment plants have been constructed in the area to serve the population. Stabilization ponds and aerated lagoons are the current wastewater treatment systems. The existing plants are overloaded and poorly managed, with the result that the effluent quality is slightly better ... Read More

As water flows over a spillway, oxygen can dissolve into water. This process has environmental importance along rivers. For example, if the amount of dissolved oxygen (DO) is too small in a river, then aquatic life such as fish die, and the river may emit an odour. Thus, there is a range of DO concentrations that define an acceptable level of water quality. Recent researches have focused on developing measurement and predictive techniques for oxygen transfer at hydraulic structures to maintain and ... Read More

Membrane bioreactors (MBRs) represent a newly developed wastewater treatment process in which secondary clarifier is replaced with membrane filtration devices. As the activated sludge is filtered by the physical barrier of a membrane, effluent does not contain suspended solids and the mixed liquor suspended solids (MLSS) level can be maintained very high (5000–30 000 mg/L). Consequently, the overall system becomes more compact and sludge retention time in the aeration basin can be increased to 20–100 days. One of the biggest limitations of cross-flow-type MBR processes ... Read More

Although it is well documented that ground water extraction (i.e., pump and treat) has limited potential for restoring aquifers to pristine conditions at most sites, it is still the most widely used technology for controlling plume migration and protecting potential receptors. Much of the early work in remediation hydrogeology focused on ground water capture problems, and various methods using analytical solutions and numerical models have been developed for capture design and assessment. One of the most common approaches for capture analysis is ... Read More

Anthropogenic acidification seriously hit Swedish lakes and watercourses from the early 1960s and onwards following the increased emissions of sulphur oxides in Europe. A national remediation programme through large-scale liming of inland waters was launched in 1976. Although the acid deposition now continuously declines, an improved liming programme is still in action treating ca. 6000 lakes. The aim is to detoxify the water by restoring pH and alkalinity thereby making it available for acid-sensitive or Al-sensitive biota. Effects and experiences of acidification ... Read More

Cotton Gossypium spp.is a major crop grown throughout many arid regions of the world.Because large quantities of irrigation water are needed to producecotton in these regions, achieving maximum crop productivity per unitof applied water has become critical as costs for water and constraintson water availability increase. Findings from a number of previousfield investigations conducted in the desert southwestern U.S. andother arid locations suggest that final lint yields for cotton areoften greater when the irrigation interval is shorter . summarized the results from ... Read More

Nearly .million hectare of agricultural land in India is estimated to have goneout of cultivation due to development of waterlogging and soilsalinity/alkalinity .Thus, the issue whether irrigated agriculture can be sustained on along term basis has been raised at many forums. Studies in India haveconfirmed the technical and economical feasibility of horizontalsubsurface drainage to reclaim waterlogged saline lands, to improveproduction and productivity in irrigation commands and to establishsustainable irrigated agriculture. Although drainage at the field scalein India is still in its infancy, ... Read More

Irrigatedagriculture in Pakistan's Indus basin suffers from waterlogging andsalinity. Seepage from the extensive canal system and deep percolationfrom irrigated fields, combined with flat topography, have led to highwatertables. Salts are added to the soil with the irrigation water andthrough capillary rise from the shallow watertables. Since the s,subsurface drainage systems have been constructed in Pakistan to tacklethese problems. Subsurface drainage systems can control the watertable,limit salinization through capillary rise, and facilitate the leachingof salts.In areas underlain by fresh groundwater  public deep tubewells ... Read More

Inorder to aid the design and operation of activated sludge systems, thesoftware based on dynamic models belonging to the Activated SludgeModels is frequently used ASIM, SYMOS. Activated Sludge Models ASM,ASM-ASMd, ASM proposed by the IWA formerly IAWPRC, then IAWQ taskgroup have shown to be a good compromise between the complexity of theactivated sludge processes and the prediction of biological wastewatertreatment under dynamic conditions .However, a successful application of such modelling requires theestimation of kinetic and stoichiometric parameters as well aswastewater and activated ... Read More