Eco-Efficiency of Drinking Water Treatment

International Journal of Environment and Waste Management, 2021

Due to the increased environmental concern; there is a considerable pressure on the water authorities for the safe treatment and disposal of sludge. It is very important to choose a suitable sludge treatment and disposal system, which is both economical and technically feasible. In this article, sludge characteristics, quantities and sources will be outlined. A detailed sludge management and treatment methods will be presented. Sludge reuse, incineration, landfilling and disposal were also considered. The study concluded that sludge management should be considered when designing and operating WTPs, adopting beneficial reuse options of sludge will become very essential and it is necessary to investigate the appropriate options for formulating long term sludge management plans under strict environmental regulations. The study recommended that sludge must be treated and disposed of in a safe and effective manner. Great emphasis is to be enforced to minimise the quantity of generated sludge, more studies should be conducted to develop suitable sludge management plans, when applying sludge reuse in agricultural purposes it is highly recommended to investigate the long term effects of sludge reuse, and finally the environmental impacts of different of sludge disposal methods should be evaluated.

Water environment research : a research publication of the Water Environment Federation, 2016

In Egypt, water treatment consumes about 365,000 tons of aluminum sulfate and produces more than 100 million tons of sludge per year. The common disposal system of sludge in Egypt is to discharge it into natural waterways. Toxicity of aluminum, environmental regulations and costs of chemicals used in water treatment process and sludge treatment led to evaluation of coagulant recovery and subsequent reuse. The present work aimed at aluminum recovery from sludge of El-Shiekh Zayd water treatment plant (WTP) to produce aluminum sulfate coagulant. Sludge was characterized and effect of five variables was tested and the process efficiency was evaluated at different operating conditions. Maximum recovery is 94.2% at acid concentration 1.5N, sludge weight 5g, mixing speed 60 rpm, temperature 60 oC and leaching time 40 min. Then optimum conditions were applied to get maximum recovery for aluminum sulfate and compared to commercial coagulant on raw water of El-Shiekh Zayd (WTP).

Mediterranean Journal of Chemistry

Treatment of the surface water of the city of Khenifra combines a conventional treatment and a membrane process unit (reverse osmosis). The conventional treatment in question uses an aluminium base reagent in the form of Aluminum sulphate that may cause leaks of Aluminum called "residual Aluminum" in the filtered water. The objective of this work is to study the elimination of residual aluminum, resulting from the conventional treatment, for a better operation of the demineralization unit by Reverse Osmosis, located downstream. Indeed, according to the requirements of the supplier of the membranes, the residual aluminum content should not exceed 0.05mg/L. The jar test remains the most used test, at the level of the laboratories, which allows optimizing the doses of treatment reagents to be used in a treatment plant; particularly the aluminum sulfate coagulant. Trials of the jar test were performed and had been optimized by the application of Doehlert experimental design. The effectiveness of the treatment and the optimum conditions through the stages of treatment are achieved by monitoring the parameters: pH, turbidity and residual aluminum. The results of tests obtained by this method have shown that to achieve a better reduction of residual aluminum in filtered water (0, 03 mg/L); it is necessary to reach a pH of 6.5, using Sulfuric acid. The optimal dose of coagulant Aluminum sulfate determined under the conditions of the test is of the order of 18.5 mg/L. On the other hand, the optimization of the treatment by the recirculation of sludge (in optimal doses) showed an improvement of the turbidity of filtered water, but without any effect on residual aluminum.

The dewatering of suspensions collected in the water treatment plants is known as water sludge is becoming a critical issue in Egypt now a day as treatment of such sludge has become a must before discharging into receiving water bodies. In this research the quality of sludge produced from the different water treatment units such as clarifiers and filter wash water was analyzed. Experiments were conducted on various clarification processes including clarification by traditional clarifiers in circular and rectangular arrangement and pulsator clarifiers. Several parameters were analyzed to assess the sludge quality treatment requirements. Analyses showed that the filter wash water is recyclable water that can be safely disposed of in water streams or to be recycled back to the treatment plants. Sludge from different clarifiers included a high concentration of residual Aluminum that required further treatment. Application of Microfiltration and Ultrafiltration membranes in dead end mode for treatment of sludge from clarifiers proved high capability in removing the hazardous parameters and can be recommended for further treatment of the sludge.

Procedia Environmental Sciences, 2016

Surface water Treatment for potable supplies typically involves coagulation, flocculation, Sedimentation, and filtration processes for removing colloidal as well as suspended solids from raw water. All water treatment plants (WTPs) produce waste/residue known as water treatment sludge (WTS) during the purification of raw water. The sludge produced a WTP at Ghaziabad, India is investigated for physical and chemical characteristics. It consist of about 60% fine sand in grain size range 150-75μ. Silica, alumina, ferric oxide and lime constitute the major percentage of chemical components present in the sludge. Some heavy metals are also found in the sludge. Discharging WTS into river, streams, ponds, lakes, drains etc. or landfilling the dewatered WTS is not environment friendly disposal option. Based on the characteristics, sustainable and profitable disposal through recycling and reuse have been reviewed. Utilization of WTS in brick making, in ceramics making, in the manufacture of cement and cementitious materials and as a substitute to building materials could provide safe disposal route. Reuse in wastewater treatment, in removal of heavy metals from aqueous solutions and in nutrient reduction from laden soils and runoffs are also some of the possible alternatives. It is required to explore suitable option for developing sustainable sludge management strategies under stringent environmental norms.

Chemical Engineering Transactions

In a Drinking Water Plant the first step in purifying water is the removal of the suspended solids and other organic or inorganic compounds (silts, clays and very fine particles). The separation is based on settling processes that is carried out through coagulation and sand filtration and the resultant product in the process is sent to sludge line. In this line, the sludge is flocculated, decanted and then thickened. As the water obtained is recirculated to first-stage treatment, the concentrated sludge is dehydrated for later use. The sludge contains a large amount of flocculants and as a result, the sludge recirculation would be possible so as to reduce the dosages of the chemical polymer streamlining the process of dehydration. This study shows the inefficiency of the sludge recirculation, and therefore proposes sludge removal process for future designs and sludge lines projects.

The Indian food processing industry is one of the largest in the world in terms of production, consumption, export and growth prospects. Increase industrialization with literacy and affluence has given a considerable push to the food processing industry growth. Characteristics of food industry wastewater depict wide variation due to the distinct the type of products manufactured, raw materials used, processing technique etc. Wastewater poses pollution problems due to its high COD, BOD, TSS, excessive nutrient compounds like nitrogen and phosphorous etc. The effluents from the food processing industry contain matter in suspension, as well as organic and inorganic compounds in solutions, due to which the load on treatment facility increases leading malfunctioning. It is therefore preferable to provide effective primary treatment, using different coagulant and coagulants aids thus the organic load on secondary biological treatment reduces. Keeping this in view, coagulants, Aluminum Sul...

Journal of Sustainable Civil Engineering and Technology

The rate of population growth and river pollution are significant factors contributing to the increase in water demand in Johor. Generally, this may affect the quality of water treated at one of the biggest water treatment plants in Johor namely Sultan Iskandar Water Treatment Plant (SIWTP). The coverage of SIWTP water supply is wide and comprise almost all area of Pasir Gudang and half of the Johor Bahru district. This situation indirectly affects consumer demand when the treated water is insufficiently supplied by the potable water supply provider due to the use of conventional coagulants in the water treatment plant process. Therefore, this is an initial study as the Poly-Aluminium Chloride (PAC) coagulant is still in the early stages of implementation at SIWTP. It is important to determine the performance of PAC coagulant in the coagulation-flocculation process of the water treatment plant. The PAC performance is compared to Aluminium Sulphate which is a common type of coagulant...

Journal of environmental management, 2016

Coagulation-flocculation process results in the generation of large volume of waste or residue, known as water treatment sludge (WTS), in the purification of surface water for potable supplies. Sustainable management of the inevitable waste requires careful attention from the plant operators and sludge managers. In this study, WTS produced with the optimum alum dose of 30 ml/L at the laboratory scale has been treated with sulphuric acid to bring forth a product known as sludge reagent product (SRP). The performance of SRP is evaluated for its efficiency in removing the colloidal suspensions from the Yamuna river water over wide pH range of 2-13. 1% sludge acidified with sulphuric acid of normality 2.5 at the rate of 0.05 ml/ml sludge has been observed as the optimum condition for preparing SRP from WTS. The percentage turbidity removal is greater at higher pH value and increases with increasing the dosage of SRP. The optimum SRP dosage of 8 ml/L in the pH range of 6-8 performed well...

Sustainability

Improved wastewater (WW) treatment contributes to preserving human life and aquatic ecosystems and acting on climate change. The use of drinking water treatment sludges (WTS) as coagulants in the primary treatment of WW contributes, in this regard, and simultaneously enables the sustainable management of this waste. In this work, the improvement of the primary treatment of real domestic WW using unmodified WTS and chemically modified WTS with sulphuric and hydrochloric acids (reactive sludges—RSs) as coagulants was evaluated. The evaluated WTS contains a higher fraction of inorganic solids and is mainly an amorphous material. The wet WTS (W-WTS) showed a better performance in enhancing WW clarification (up to 76%), as measured by turbidity in comparison with the dry WTS (D-WTS). All RSs improved this performance considerably (up to 98%), and of these, the sulphuric reactive sludge generated from the W-WTS (SRS-W) showed the lowest costs associated with acid consumption for activatio...