Performance Evaluation of Trickling Filter and Extended Aeration of Wastewater Treatment Plants

In recent decades, there has been increasing interest in wastewater treatment because of its direct impact on the environment and public health. Over time, other forms of treatment have been developed and modified, including extended aeration. This process is included in the suspended growth system. In this paper, a comparative study was conducted between the efficiency of the extended aeration plant and that of the trickling filter plant in removal of BOD and COD. The method of comparison was done by knowing the value of the pollutant before and after the treatment and then extract the removal ratio of each pollutant within each plant. The results showed that the percentage of removal of BOD in the trickling filter was 79.5% while in extended aeration was 90.7%. The efficiency of COD removal was 60% in trickling filter and 86% in extended aeration. The study was carried out at the Barrakiyah WWTP in Najaf province in Iraq. As the plant contains these two types of treatment, and the study has been achieved through monthly examinations over a full year.

Influence of heat pumps inclusion in deaeration scheme of heating network make-up water on the operating modes of the TPP

The idea of using a heat pump in the heating cycle seems quite attractive at first glance, but requires careful analysis of the effect of the heat pump on the operation mode of the thermal power plant. In this work we analyze the influence of the heat pumps inclusion in deaeration schemes of heating network make-up water on the operating modes of the CHP. All calculations were made for the real scheme of the de-aeration plant DSV-800 of the power unit with a T-100 turbine. The calculations were carried out for three schemes of heat pumps of different capacities. The calculations took into the account various uses of the heat received from the heat pumps.

Zooplankton of Mokraya Sura River

Structural and functional characteristics of zooplankton as well as the results of biotesting were researched to indicate the ecological status of Mokraya Sura river sites. Zooplankton sampling was performed at the sites of Mokraya Sura river in autumn 2014 and in spring 2015. Species composition and abundance of zooplankton showed that zooplankton is most depressed at the upper sites of the river due to joint effect of slime accumulation eutrophication and industrial sewage. Biotesting results estimated water quality of the site near aeration plant sewage emergency discharge as most polluted of the river sites where large abundance and biomass of zooplankton were created mostly by planktonic rotifers. Large figures of filter-seeding crustaceans as well as low saprobity index indicate improvement in water quality at the sites 3 km and 2 km upstream from the river mouth.

Technological and Constructive Proposals on Sand Trap and Removal from Industrial and Domestic Waste Water

The studies on operating effectiveness of sand traps in partially acting facilities of the Yerevan Aeration Plant have shown that along the satisfactory clarification of silts (sand) of mineral origin at the facility bed materials of organic origin are also trapped causing sand traps failure their main function which is clearly separation of the two types of waste waters. In addition serious problems and difficulties arise also in the sand removal. Therefore, in this paper it is suggested both technological ( grounded reduction of the number of sand traps and including in the mechanical unit clarification plants equipped with bioflocculation chambers) and constructive (by substantially decreasing the length of sand traps) solutions. It also is suggested for the first time to apply a new technology designed to remove the sand from sand traps both in the above aeration plant and new industrial and domestic waste water clarification plants under engineering design.

Practical aspects of the oxygen supply/sludge activity relationship

The basis of the sludge activity concept is described together with experimental applications. As a result of these it has been concluded that activated sludge plants normally operate under oxygen limiting conditions and that increases in the rate of aeration which enable the plants to deal with greater loadings require equal increases in the sludge and dissolved oxygen concentration. The increases necessary are not proportional to the increased loadings but to the square roots of them. Increase in turbulence of the mixed liquor does not appear to be a factor of importance down to retention periods of the order of two hours when treating an average strength sewage, but may have had an effect at lower aeration periods. Calculations using data obtained from a hybrid mechanical aeration plant at Manchester indicate that the percentage oxygenation of the sludge in a low intensity carbonaceous oxidation plant may be as low as 15%. Even in a high intensity plant treating sewage in two hours the calculations gave an estimate of 33% aerobicity. It appears that the sludge activity approach can be applied to nitrifying organisms and that they also tend to a maximum as the sludge concentration is increased. In full scale practice there will be an optimum dissolved oxygen level which gives the highest oxygen deficiency, and thus power economy, consistent with attaining the required nitrification.

Upgrading effluent quality for lagoon-based systems

To establish Best Available Technology Economically Achievable (BATEA) in non-urban communities which presently use conventional lagoon technology, an investigation was undertaken to evaluate alternatives which can be used to improve lagoon effluent and establish costs. Evaluated were the “Sutton” and the intermittent sand filtration or “New Hamburg” processes. The Sutton concept consists of a nitrifying extended-aeration plant followed by polishing lagoons, with waste sludge discharged into the lagoons. The New Hamburg concept consists of aerated or facultative lagoons, with the lagoon effluent sprayed intermittently over sand filters. The Sutton plants produce an improved effluent quality relative to conventional facultative lagoons in terms of BOD5 and TSS concentrations. Increases in ammonia concentration across the polishing pond occur after 5-7 years of plant operation, suggesting a need to implement a regular program of sludge removal from the lagoon. The New Hamburg process results in a significant improvement in effluent quality in terms of BOD5, TSS, TP, TKN, NH3-N and H2S concentrations. Approximate capital costs for upgrading the existing conventional lagoons in Ontario to Sutton and New Hamburg process facilities are estimated at US $221 million and US $93 million, respectively.