Effect Of Suspended Solids Concentration Research Articles

Effect of Suspended Solids Concentration on Clogging of Porous Media

In this study, indoor sand column experiment was used to simulate the rain flood recharging groundwater, the effect of suspended solids concentration on porous media clogging was studied. The experiment set three different particle size sand columns and different concentration of suspended matter back irrigation, 50mg/L, 100mg/L, 200mg/L, and intermittent recharge respectively, analyzed the change regulation of water flux and permeability coefficient. The results showed that:Under the same particle size, porous medium was easier to be clogged by the increase of concentration of the suspended solids; Under the same condition of the concentration of suspended solids, it was easier to recharge when the particle size of the porous medium was smaller.

Influence of operational conditions on the performance of a mesh filter activated sludge process

Recently, a new type of wastewater treatment system became the focus of scientific research, the mesh filter activated sludge system. It is a modification of the membrane bioreactor where a membrane filtration process serves to separate the sludge from the purified effluent. The difference is that a mesh filter is used instead of the membrane. Due to the much larger pore size of the mesh, the effluent is not of the same excellent quality as with membrane bioreactors. Nevertheless, it still resembles the quality of the now most widely used standard treatment system, where settling tanks are used to retain the activated sludge. At the same time, the new system features all the other advantages of membrane bioreactors including elevated sludge concentrations resulting in decreased volumina of basins and complete substitution of the settling tank. Therefore, this process presents a potential future alternative where a small footprint of the plant is required. However, so far only a few preliminary studies on this innovative process type have been done. In this paper, the effects of suspended solids concentration, flux rate as well as aeration rate on the effluent quality are discussed. Furthermore, the characteristic of the sludge floc was identified as a factor of vital importance. Therefore, another influencing parameter, the food to microorganism (F/M) ratio, which is known to have a significant effect on floc characteristics, was studied. The main result demonstrated that the process was very effective under most of the operation conditions. The suspended solids concentration in the effluent was below 12 mg l(-1), the average COD in the effluent was between 24 and 45 mg l(-1) and the BOD(5) was lower than 5 mg l(-1). High flux rates of up to 150 l m(-2)h(-1) were also achieved.

Simultaneous sewage sludge digestion and metal leaching using an internal loop reactor: effect of suspended solids concentration

The objective of this work was to determine the effects of various concentrations of solid sludge on the bioleaching of metals and the stabilisation of sludge using elemental sulphur as a substrate to remove metals by an acid bioleaching process. Two experimental series were carried out in batch cultures, in column-type bioreactors, using sulphur in the form of 25 mm diameter blocks, in a 12-litre mixture which contained 80% of primary and 20% of secondary sludge (on a dry weight basis). Both sludge types came from the waste water treatment centre of the Valcartier military base (Quebec, Canada). The suspended solids (SS) concentrations (g/l) of the first and second series (B and B’): ranged from 8 to 27 g/l, respectively, with eight concentrations per series. The results obtained during the bioleaching–stabilisation process show that the acidification rate was reduced, that the quantity of sulphate produced increased with the sludge solid concentration. But the reduction in SS and volatile suspended solids (VSS) of the leached sludge was greater than that obtained by stabilising the sludge aerobically (control). The value of the degradation constant ( k d) decreased in response to the increase in VSS. The solubilisation rates of different metals during the bioleaching stabilisation decreased as the sludge solid concentrations increased and were as follows: Cd 43–79%; Cr 22–38%; Cu 75–97%; Fe 40–54%; Mn 88–98%; Ni 25–40%; Pb 37–89%; Zn 76–100%; P 30–34%; K 47–60%. The use of sulphur in the form of blocks leads to the formation of anoxic zones in certain regions of the bioreactor, favouring bacterial denitrification. Soluble concentrations of potassium were reduced by the end of the bioleaching process, whereas soluble concentrations of phosphorus and ammonium nitrogen increased. Despite these changes, the fertilizer values of the solid phase of these sludge types were effectively preserved.

Effect of suspended solids concentration and filament type on the toxicity of chlorine and hydrogen peroxide to bulking activated sludge

AbstractToxic inhibition of three communities of filamentous microorganisms by chlorine and hydrogen peroxide was investigated in relation to the total suspended solids concentration of bulking acitvated sludges. The filament communities studied were dominated by type 1701, Sphaerotilus natans, and the combination of type 021N and Thiothrix spp., respectively. Activity of filamentous and gross biomass was assessed separately using the malachite green‐INT (MINT) test. The effectiveness of toxicants was characterized in terms of the concentration required to inhibit 50% of microbial dehydrogenase activity (IC50). IC50s were found to be proportional to total suspended solids concentration. Values for filamentous biomass were generally lower than those for gross biomass. Relative sensitivity (ratio of gross IC50 to filamentous IC50) did not vary significantly over the practical range of total suspended solids concentraton. This parameter was unaffected by the nature of the toxicant in S. natans and type 021N/Thiothrix dominated sludges, but was toxicant specific in type 1701 dominated sludge. Overall, S. natans and type 1701 were the least sensitive of the filament types studied. Bulking caused by these organisms has been successfully cured by toxicant addition in numerous past instances. It is therefore expected that type 021N, Thiothrix, and most other types of filamentous bulking can also be controlled by this technique.

A detailed investigation of physical and biological clogging during artificial recharge

An attempt was made to study the physical and biological clogging during artificial recharge with an experimental model that simulates the artificial recharging practice by considering factors such as effective infiltration rate, media size and depth, and inundation period. Recharging was investigated experimentally in terms of suspended solids (SS) removal, 3-day biological oxygen demand (BOD3) removal and chemical oxygen demand (COD) removal at different sand sizes and infiltration rates. To understand the physical phenomenon involved, the effect of suspended solids concentration and initial infiltration rate on cumulative discharge was studied and verified using a simple mathematical model. The simulated cumulative discharge profiles were comparable with the experimental profiles. This indicates that an empirical relationship can be successfully used to predict the biological clogging at different recharge rates. The effect on headloss was also discussed.

Variation of sludge volume index with activated sludge characteristics

Activated sludge samples from 2 laboratory units and 12 sewage treatment plants were examined to determine the effect of filamentous microorganisms, floc size and suspended solids concentration on SVI. An attempt was also made to correlate SVI to zone settling velocity. At a suspended solids concentration range of 700–4800 mg 1 −1 there was no effect of filamentous microorganisms at filament length concentrations below 10 7μm (mg SS) −1. However, when it was over 10 7 μm (mg SS) −1 SVI increased sharply with increasing concentrations of filamentous microorganisms. At all suspended solids concentrations examined SVI varied with floc size at filament length concentrations below 10 μm (mg SS) −1. But, at filament length concentrations higher than this level, no effect of floc size on SVI was observed. The effect of suspended solids concentration on SVI was examined at different levels of filament lengths. It was found that the shape of SVI-suspended solids concentration curve varied with the level of filament lengths. A well defined relationship was found between SVI and zone settling velocity at all suspended solids concentrations examined.