Modeling of the Suspended Solid Removal of a Granular Media Layer in an Upflow Stormwater Runoff Filtration System

Upflow granular media filtration devices are widely used for stormwater runoff treatment. However, the system performance is not well characterized due to the irregular removal of suspended solid (SS) in the pretreatment (sedimentation) chamber and, hence, its irregular input to the media layer. In this regard, the performance of the granular media layer of an upflow filtration system is investigated herein by the use of various models. Due to the significant variation in the SS concentration of the influent and effluent to and from the media layer, the deep bed filtration model, the k-C* model, and the porous media capture model provide limited descriptions of the system performance. By contrast, the performance is well described using the kinetic model, the modified k-C* model using a specific deposit, and the modified porous media capture model using a specific deposit. The parameters of the latter models are shown to be in good correlation with the filtration velocity, SS removal, and specific deposit. The results suggest that modeling using a specific SS deposit can provide an accurate description of the granular media layer performance under a highly variable influent SS concentration.

Improving the technology of gold ore X-ray radiometric separation

Introduction. Gold ore pre-concentration is an urgent issue that can efficiently be solved by the technology of X-ray radiometric separation (XRS). Quarts and quarts-sulfide gold ore XRS is based on the methods of indirect sorting by gold accompanying chemical elements or genetic associate minerals laying the foundation for the creation of separation characteristics for these ores. Additional separation characteristics are required for efficient gold-quartz and gold-quartz-sulfide ore sorting; Irgiredmet Research Institute works on these characteristics search and development. Research methodology. Optimal ore separation characteristics for each specific deposit are chosen after studying and analyzing the spectral information acquired at XRF separators when detecting secondary characteristic radiation from each specific deposit ore samples. The recent modernization of XRF separators significantly enhanced the technological capabilities of XRS concerning intensive search and study of new separation characteristics for gold ore. It has been established that most ores can be efficiently sorted by three characteristics. Research results. A new method of gold ore XRS has been developed which consists of simultaneously applying three, two, or one decision criterion of a lump separation depending on the type, geologicalmineralogical properties, and material composition of the processed ore

Physical Experiment and Modeling of the Transport and Deposition of Polydisperse Particles in Stormwater: Effects of a Depth-Dependent Initial Filter Coefficient

The artificial recharge of stormwater is an effective approach for replenishing aquifer and reduce urban waterlogging, but prone to clogging by suspended particles (SP) that are highly heterogeneously sized. In this paper, the transport and deposition of SP in a sand column were investigated under a constant flow condition, for five stormwater concentrations. A depth-dependent initial filter coefficient is incorporated into the conventional filtration model. This modified model considers the heterogeneity of the particle population by lumping the capture of heterogeneous SP into a capture probability. The good agreement between the results of the modified model and the experimental results of measured outlet concentration and average specific deposit validated the modified model. The experiment data and the simulation results both indicate that the highly hyper-exponential retention profiles are caused by non-uniform deposition of heterogeneous SP; and, the conventional model was found to homogenize the spatial distribution of SP retention and overestimate retention of the porous medium. Local and overall permeability reductions were assessed by an empirical relationship and the Kozeny-Carman model, respectively. It is shown that consideration of polydisperse suspended particles is of primary importance. This study highlights the effects of polydisperse particles on SP deposition in a saturated porous medium.

Removal of Volatile Solids from Greywater Using Sand Filters

Sand filtration is a primary stage of treatment for reuse of greywater. This study aimed at assessing the volatile solid removal efficiency of a sand filter and imitating its performance using analytical simulation. This study used artificial greywater, medium sand as a filtering material, and nine PVC cylinders as filter columns. Samples of the sand were collected after 6, 14 and 21 days, with the aim of specific deposit determination. The vertical distribution of specific deposit (volatile solids) in the sand filters was typical for gravitationally operated sand filters. Relatively high removal efficiency of volatile solids (51–60%) was achieved at relatively low cumulative hydraulic load. The average removal efficiency of organic compounds (detected as chemical oxygen demand) was 26.8%. Maximum specific deposit was achieved for a cumulative hydraulic load of 363.6 m. The filter coefficient was identified empirically for application of the Iwasaki formula. The filter coefficient λ was corrected for a better fit of the modelled values with measured values.

Problems and Perspectives of Single-Industry Towns in the Far East

The research features the topical problem of formation and functioning of single-industry towns. The paper gives the quantitative parameters of some single-industry towns of the Russian Federation and the Far East, as well as the main factors of their development and related problems, such as unemployment, demography, migration, and absence of residents-investors. For example, a program of complex development of single-industry towns has been developed and implemented in the Republic of Sakha (Yakutia) with the main focus on creating new jobs. As a result, industrial enterprises are expected to attract at least 10,000 people from the local population by 2020. The author offers some possible solutions and substantiates the expediency of feasibility studies when choosing a method of development of each specific deposit. The studies should be based on the production capacity of the future enterprise. The obtained data predict when the local deposits will be exhausted and, thus, the prospective operation life of the settlement. Only after that, either stationary settlement or rotational team method can be chosen.

How to Measure Specific Deposit Washout and Backwash Efficiency of Granular Filters

Practical experience shows that water treatment filters develop problems over time due to the routine running of the filter, including backwashing. There are difficulties in maintaining filters in good condition, given the eutrophic state of many South African raw waters, high water temperatures and the development of difficult-to-remove biofilm as a result. Such difficulties are often related to deposits accumulated on the filter media and it is, therefore, expected that the backwash system should be good enough to ensure that the filter is kept clean in the long run. This paper deals with a fairly simple operational option to significantly improve backwash efficiency at treatment plants where air and water are used consecutively. The paper describes methods used and typical results obtained in the testing of the quantitative benefits of multiple wash cycles. Multiple washing shows great promise for improving backwash efficiency, with an average of an additional 40% to 50% of the solids that would have been washed out with a single wash, removed by a second wash. Furthermore, third and even fourth washes continue to remove additional dirt from the filter. Multiple washing, therefore, may be a useful tool for the effective rehabilitation of a filter, as well as for routine operation procedures.