Domagoj Nakić

Use of sludge generated at WWTP in the production of cement mortar and concrete

U radu je opisana problematika vezana uz generiranje i zbrinjavanje mulja s UPOV-a (uređaja za prociscavanje otpadnih voda) u Hrvatskoj. Poseban osvrt je dan na mogucnost i opravdanost koristenja pepela dobivenog spaljivanjem mulja. Naglasak je stavljen na ugradnju pepela u betonskoj industriji, pri proizvodnji cementnog morta i betona. U radu su opisani rezultati do sada provedenih istraživanja u okviru svjetske prakse, s primarnim osvrtom na utjecaj ugradnje pepela na karakteristike cementnog morta i betona.

Management of sewage sludge – new possibilities involving partial cement replacement

An increasing trend of sludge generation at wastewater treatment plants (WWTP) has been observed in developing countries like Croatia. Thermal processing of sewage sludge facilitates its further management, although ash is generated as new waste in the process. The proposed approach, while eliminating the need to dispose ash at non-hazardous waste disposal sites, directly reduces not only the sludge and ash disposal costs, but also the raw cement production costs. All analysed technical and environmental requirements are met when 20 % of cement is replaced with ash.

Use of MID-MIX® treated sewage sludge in cement mortars and concrete

AbstractDeveloping beneficial applications for sewage sludge is a key challenge in many countries, given the amount of sludge generated and the disposal or recycling options currently available. Se...

Effect of lime addition during sewage sludge treatment on characteristics of resulting SSA when it is used in cementitious materials

Final disposal of sewage sludge is important not only in terms of satisfying the regulations, but the aspect of choosing the optimal wastewater treatment technology, including the sludge treatment. In most EU countries, significant amounts of stabilized and dewatered sludge are incinerated, and sewage sludge ash (SSA) is generated as a by product. At the same time, lime is one of the commonly used additives in the sewage sludge treatment primarily to stabilize the sludge. In doing so, the question arose how desirable is such addition of lime if the sludge is subsequently incinerated, and the generated ash is further used in the production of cementitious materials. A series of mortars were prepared where 10-20% of the cement fraction was replaced by SSA. Since all three types of analyzed SSA (without lime, with lime added during sludge stabilization and with extra lime added during sludge incineration) yielded nearly same results, it can be concluded that if sludge incineration is accepted solution, lime addition during sludge treatment is unnecessary even from the standpoint of preserving the pozzolanic properties of the resulting SSA. Results of the research carried out on cement mortars point to the great possibilities of using SSA in concrete industry.

Role of primary settling tanks on SBR plants for secondary treatment

SBR tehnologija predstavlja modifikaciju konvencionalnog postupka s aktivnim muljem na principu saržnog punjenja bioreaktora. Smanjenje ukupnog potrebnog volumena SBR reaktora s drugim stupnjem prociscavanja može se ostvariti uz prethodnu taložnicu kao prvi stupanj prociscavanja ispred SBR reaktora, sto je osobito izraženo kod uređaja za prociscavanje veceg kapaciteta kojima prethodi razdjelni sustav odvodnje. Uz izgradnju prethodnih taložnica ispred SBR reaktora, smanjuje se potrosnja kisika u odnosu na SBR uređaje bez prethodnih taložnica.

Korištenje mulja s UPOV-a u proizvodnji cementnog morta i betona

U radu je opisana problematika vezana uz generiranje i zbrinjavanje mulja s UPOV-a (uređaja za prociscavanje otpadnih voda) u Hrvatskoj. Poseban osvrt je dan na mogucnost i opravdanost koristenja pepela dobivenog spaljivanjem mulja. Naglasak je stavljen na ugradnju pepela u betonskoj industriji, pri proizvodnji cementnog morta i betona. U radu su opisani rezultati do sada provedenih istraživanja u okviru svjetske prakse, s primarnim osvrtom na utjecaj ugradnje pepela na karakteristike cementnog morta i betona.