Testing IKO-R enhanced coagulation pilot plant

Summary

An experimental plant with a capacity up to 20 m3/h was developed for enhanced coagulation of surface and waste water as well as storm water. The treatment process is based on sedimentation of inclusions together with coagulated flocs under the optimal conditions of chemical addition and mixing. To enhance the sedimentation process sludge recycling from the settling tank was provided that ensured the formation of big flocs. Pilot tests of the plant were carried out to evaluate the efficiency of removing suspended solids and phosphorus from the effluent during tertiary treatment at the Podolsk wastewater treatment facilities in the Moscow Area. The capacity of the plant during testing varied from 3 to 15 m³/h. At steady operation of the settling tank no sludge washout was observed. During longer tests the capacity was 8–10 m³/h; in terms of the cross section of the settling tank the specific capacity (flow rate) was 5–7 m³/(m²·h). Time to reach the steady state conditions was 5–10 minutes. At that the efficiency of phosphorus removal was 80%, permanganate value was reduced by 54% and suspended solids concentration was reduced by 58%.

Key words

coagulation , coagulant , flocculant , sludge recirculation , enhanced treatment , pilot plant

Reconstruction of high colored and low turbidity water treatment facilities

Summary

By the example of Severodvinsk municipal water treatment facilities the specific features of the upgrade and partial retechnologisation of the high colored and low turbidity water treatment process are considered. The measures were aiming at meeting the regulatory requirements and minimizing the water treatment cost. Such processing technologies as sludge recycling in combination with the use of flocculant, upgrading the mixing and flocculation chambers with the use of mechanical mixers, automation of dosing equipment with continuous instrument control provide for the sustainable and efficient operation of the water treatment facilities. The implemented water treatment technology including the use of coagulant and organic flocculant as well as coagulation in contact with sludge separated from the settling tanks and subsequent filtration in sand-dolomitic bed filters allows producing drinking water that meets the current standards.

Key words

rapid filter , chemical workshop , sludge recirculation , high colored and low turbidity water , humic substances

The efficiency of enhancing wastewater sludge digestion

Summary

The results of experimental studies of enhancing wastewater sludge digestion as applied to the process flow scheme of the Kur’ianovskie Wastewater Treatment Facilities are presented. The specialists of the R&D Centre of «Mosvodokanal» JSC tested in the laboratory and calculated the economic efficiency of three options of digestion enhancement: sludge processing in the process of thermal hydrolysis before digestion; increasing the hydraulic retention time; increasing the solids retention time. The studies were aiming at comparing the efficiency of sludge digestion when using the given technology solutions. Increasing the hydraulic retention time (HRT) is caused by sludge thickening enhancement before digesters. The experience of the Prague wastewater treatment facilities shows that thickening enhancement alone provides for efficiency improving by a few percent. This was confirmed in the process of laboratory experiments in the R&D Centre. Sludge pretreatment before digestion with the purpose of accelerating the hydrolysis of stable organic matter, e. g. thermal hydrolysis, ensures significant enhancement of the entire process by activating the slowest stage of hydrolysis; as a result, the decomposition of ash-free matter and biogas output were increased by 10–30%. However, this type of technology involves high capital expenditures. Increasing the solids retention time (SRT) is achieved by retaining solids in the digester while maintaining the hydraulic retention time (HRT). This can be ensured by retaining or recycling solids to the digester. The technology of sludge recycling serves as an example that provides for the high organic matter decomposition by means of increasing the solids retention time without any significant capital investments. Thus, following the results of the studies the given technology has been accepted as a most cost-effective.

Key words

thermal hydrolysis , wastewater sludges , sludge recirculation , digestion enhancement , decomposition of organic matter