Aušra Mažeikienė

Disintegration impact on sludge digestion process

ABSTRACT The anaerobic sludge digestion is a widely used method for sludge stabilization in wastewater treatment plant. This process can be improved by applying the sludge disintegration methods. As the sludge disintegration is not investigated enough, an analysis of how the application of thermal hydrolysis affects the sludge digestion process based on full-scale data was conducted. The results showed that the maximum volatile suspended solids (VSS) destruction reached the value of 65% independently on the application of thermal hydrolysis. The average VSS destruction increased by 14% when thermal hydrolysis was applied. In order to have the maximum VSS reduction and biogas production, it is recommended to keep the maximum defined VSS loading of 5.7 kg VSS/m3/d when the thermal hydrolysis is applied and to keep the VSS loading between 2.1–2.4 kg VSS/m3/d when the disintegration of sludge is not applied. The application of thermal hydrolysis leads to an approximately 2.5 times higher VSS loading maintenance comparing VSS loading without the disintegration; therefore, digesters with 1.8 times smaller volume is required.

The suitability of natural and synthetic filter material for the removal of petroleum products from the aqueous media

AbstractPetroleum products that have leaked into the natural environment are very hazardous. They are particularly dangerous for aquatic ecosystems. The major part of oils is carried into natural water bodies together with the surface outwashes from urban areas. One of the most inexpensive and easiest methods of the removal of oil contaminants from runoff is filtering. The authors of this study examined several synthetic substances (Duck and Reo-dry), and several vegetal materials (shredded stems of reeds, bulrush and lesser bulrush) and compared their filtration characteristics with the characteristics of the synthetic substance Fibroil now widely used for filtration. The authors of this study feel that the materials tested are suitable for the petroleum removal filter medium. Industrialists submit specifications of their products that were recorded under ideal conditions, at a low filtration rate. The authors studied filter material of natural origin as well as synthetic ones by simulating actual condit...

Removal of ammonium ions from digested sludge fugate by using natural zeolite

AbstractWastewater treatment loadings with total nitrogen can increased by introducing fugate that is saturated with ammonium ions, generated when dewatering wastewater treatment sludge. In this article the possibility to reduce the concentration of ammonium ions in the fugate by the use of natural zeolite (Transcarpatian clinoptilolite) has been analysed. Lab-scale experiments were carried out with different particle sizes zeolite: 0.8–1.6 mm, 1.6–2.5 mm and 2.5–3.2 mm. At the first stage of the experiments, zeolite particles were mixed with fugate and left to settle until a 99% efficiency of ammonium ion removal was achieved. At the second stage, ammonium ions were removed from the fugate by filtering this liquid through zeolite where the 70–92% efficiency was achieved. Zeolite saturated with ammonium ions possibly can be used in agriculture as nitrogenous fertilizers. Obtained fertilizer grade of zeolite saturated with fugate can also be produced from the high ammonium nitrogen concentration side-strea...

Oil removal from water by filtration

AbstractOil-contaminated water is most commonly treated with sorbent materials. In this experimental study, a fibrous sorbent material Fibroil was used. The experiment was carried out with tap water and clarified stormwater. It was determined that the retention of contaminants is worse at high flow rates, which reduces the efficiency of treatment. Sorbent materials retain suspended solids and reduce water turbidity; thus, the water must be clarified and pretreated before it is supplied to the sorption fillings. For the efficient use of sorbent material properties, the concentration of suspended solids in water supplied to the filter must be below 20 mg/L, while water turbidity must be below 15 NTU and the flow rate must be below 20 m/h. If the pressure loss in the sorption filler increases to 25 cm, it can be predicted that the oil concentration after treatment would exceed permissible environmental requirements (5 mg/L). The derived sorption and hydraulic properties of the material can be used to evaluat...