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Purpose: Sludge treatment and reuse as a fertilizer is of great significance in Gaza Strip. This study aimed to treat sludge generated at North Gaza WWTP, to produce rich nutrients fertilizer, to apply it in a greenhouse, and to compare its performance with different fertilizers. Method: The concept of drying beds was applied to 1500 kg of sludge, which was exposed to the sun for 75 days; it was tested every 15 days to measure quality parameters. Results: After 45 days, complete removal of F.C., E-Coli, salmonella, and helminths was achieved. The treated sludge had NPK of 3.3, 14 and 1.4% respectively. The treated sludge showed to be a good competitor to the commercial fertilizer that had NPK of 3.2, 1.9, 2.3 % respectively. The treated sludge and commercial fertilizer were tested for heavy metals; concentrations of Cd, Pb, Cu, Hg, Cr, Ni, and Zn in the treated sludge were 1.4, 110, 0, 0, 80.5, 26.4 and 1369.7 mg.kg-1; while for the commercial fertilizer they were 1.67, 141.3, 142, <0.001, 144.2, 13.45, and 437.5 mg.kg-1 respectively. Conclusion: Heavy metals' concentrations were in line with Palestinian, Jordanian, Iraqi, and most European Countries' standards. The treated sludge, local fertilizers, and mixtures were applied in a greenhouse, and development of selected crops was monitored. The seedlings' best development occurred when being fertilized with the treated sludge followed by commercial fertilizer. Crops fertilized by treated sludge were free from F.C. and E-Coli. The study recommended further investigating efficient treatment techniques to shorten the treatment period. [ABSTRACT FROM AUTHOR]

Identification and ecological diagnostics of the influence of basic load parameters (the cumulative effect of air temperature, the amount of precipitation) is a fundamental aspect of the wastewater sludge treatment at drying beds. The positive dynamics of atmospheric precipitation and the long-term functioning of natural and technical systems for wastewater sludge treatment under the influence of excessive atmospheric moisture does not allow the treatment/drying of precipitation, which provokes soil pollution with subsequent diffusion of pollutants into groundwater, which leads to the degradation of the natural environment components interacting with drying beds. The article is devoted to the adaptation of the process of treatment/drying of wastewater sludge at drying beds. The method includes identification of the dynamics of climatic factors of a long-term chronological series, which makes it possible to predict the effect of atmospheric precipitation on the wastewater sludge drying. The costs for the implementation and subsequent use of the proposed method are absent or insignificant (in the conditions of an increase in usable area during the modernisation of existing drying beds) in comparison with the costs of well-known and widespread methods of deliquefaction. [ABSTRACT FROM AUTHOR]

Copyright of Universitas Scientiarum is the property of Pontificia Universidad Javeriana and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Tikrit Journal of Engineering Sciences is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Solar drying has been used extensively to dewater biosolids for ease of transportation and to a lesser degree to reduce pathogens prior to land application. The nitrogen in biosolids makes them a relatively inexpensive but valuable source of fertilizer. In this study, nitrogen loss from tilled and untilled biosolids was investigated during the solar drying process. Samples of aerobically and anaerobically digested biosolids during three solar drying experiments were analyzed for their nitrate (NO3-) and ammonium (NH4+) ions concentrations. Nitrogen losses varied depending on the solar drying season and tillage. Although not directly measured, the majority of nitrogen loss occurred through ammonia volatilization; organic nitrogen content (organic N) remained relatively stable for each sample, nitrate concentrations for the majority of samples remained below detectable levels and the decline of ammonium-nitrogen (NH4+-N) generally followed the trend of moisture loss in the biosolids. [ABSTRACT FROM AUTHOR]

The aim of this study was to compare the regrowth potentials of wastewater sludges dried in two pilot-scale drying processes namely, Open-Sun Sludge Drying Bed (OSDB) and Covered Sludge Drying Bed (CSDB). Quicklime and/or coal fly ash were added to raw sludge samples prior to drying processes in order to enhance bacterial inactivation. Following three drying cycles (March-April, June-July and August-October), sludge samples were taken from the beds for the regrowth experiments. Addition of alkaline materials prevented the regrowth of faecal coliforms in all rewetted samples except for the samples obtained after the rainfall events in OSDB. Rewetting of these samples in the regrowth experiments increased faecal coliform numbers by 3.5-7 log units. In contradiction, the observed bacterial numbers in rewetted alkaline samples from CSDB were below the EPA Class B criterion (2 million MPN g-1 dry sludge). The combination of additional heat from solar collectors, protection from the rain and the unfavourable living conditions owing to alkaline materials appeared to inactivate bacteria more effectively in CSDB and hence eliminated regrowth potential more efficiently. [ABSTRACT FROM AUTHOR]

The modeling of gravity driven batch filtration is dicussed in which the slurry is considered to comprise a flocculated suspension. The gravity belt thickener and the sludge drying bed are commonly employed devices to which this model may be applied. In both devices, the slurry is applied to a filter medium through which the filtrate passes under the influence of the hydraulic head of the slurry. The solids are retained on the filter and accumulate in up to 3 distinct zones. A fourth zone of clear liquor may also exist above the solids zones. As the filtration process proceeds, the hydraulic head declines because of the discharge of filtrate. A model of this filtration process is developed together with methods for its solution. The model links the filtration rate to the physical properties of the slurry through constitutive relationships for the permeability and compressive yield stress. [ABSTRACT FROM AUTHOR]