There are two kinds of wastewater that may originate at a dairy plant: post-production and nonproduction waste. Dairy wastewater treatment is a process consisting of several stages. In the pre-treatment stage, fat and sand is removed from wastewater. The second stage treatment consists mainly in aerobic treatment with activated sludge, advanced oxidation methods and an anaerobic treatment. In recent years, more and more plants have been treating their wastewater in SBR type reactors, because they are flexible at work and enable the user to change conditions to suit the variable quality of raw wastewater. The research on the kinetics of the wastewater treatment process in an SBR reactor has been conducted. The removal of several factors such as nitrogen compounds, TOC, phosphorus and the kinetics of oxygen concentration and redox potential have been analyzed. The experiment was carried out in two 12 dm3 volume SBR reactors in a lab-scale. The SBR reactors were operated with a cycle time of 12 hours with three hours of filling, seven hours of aeration, an hour of sedimentation, half an hour of decantation and half an hour of technical break. In presented research average parameters of raw wastewater were: TOC 329 mg C/dm3, ammonium nitrogen I I. 15 mg NN1,/dm3, and total phosphorus 15.42 mg P/dm3.

In this study, the dependence between volumetric exchange rate (n) in an SBR (Sequencing Batch Reactor) with a modified cycle and simultaneous nitrification and denitrification (SND) efficiency during the treatment of anaerobic sludge digester supernatant was determined. In the SBR cycle alternating three aeration phases (with limited dissolved oxygen (DO) concentration up to 0.7 mg O2/L) and two mixing phases were applied. The lengths of each aeration and mixing phases were 4 and 5.5 h, respectively. Independently of n, a total removal of ammonium was achieved. However, at n = 0.1 d-1 and n = 0.3 d-1 nitrates were the main product of nitrification, while at n = 0.5 d-1, both nitrates and nitrites occurred in the effluent. Under these operational conditions, despite low COD/N (ca. 4) ratio in the influent, denitrification in activated sludge was observed. A higher denitrification efficiency at n = 0.5 d-1 (51.3%) than at n = 0.1 d-1 (7.8%) indicated that n was a crucial factor influencing SND via nitrite and nitrate in the SBR with a low oxygen concentration in aeration phases.

The paper presents the results of an experiment with sugar-industry waste (molasses) as an organic carbon source for denitrification. The investigations concern the influence of untreated molasses and molasses after pretreatment (hydrolyzed molasses) and variable COD/N ratio (6.0: 5.0: 4.0) on denitrification efficiency and kinetics. Moreover, sludge production, in dependence on tested carbon source, was estimated. Al COD/N ratio 6 and 5, regardless or applied organic carbon source (untreated molasses. hydrolyzed molasses), the denitrification efficiency was over 98%,. However. from kinetic analysis it results that a kind or carbon source and COD/N ratio have an effect on denitrification rate. The highest nitrate removal rate - 9.5 mg N,0/(dm-1-h) was obtained al COD/N = 6 in the reactor with hydrolyzed molasses as a carbon source and the lowest - 5.14 mg N,0J(dm1-h) in reactor with untreated molasses at COD/N = 5.0. The lowering or COD/N ratio to 4 caused decrease otthe process efficiency to 27.6% (untreated molasses) and 44.3% (hydrolyzed molasses). Hydrolyzed molasses as a carbon source caused higher production of activated sludge. In reactors with untreated molasses Y equals 0.40 mg VSS/rng COD at COD/N ratio 6 and 0.31 111g VSS/111g COD at COD/N ratio 5. In reactors with molasses alter hydrolysis Y, were 1.35-lolcl and 1.5-lold higher, respectively. Since, the molasses hydrolysis results in rising costs of wastewater treatment and cause higher sludge production, untreated molasses seems to be a more suitable carbon source for dcniuification.

The paper presents preliminary results of investigations on a relationship between turbidity and other quality parameters in the SBR plant effluent. The laboratory tests demonstrated a high correlation between an effluent turbidity and a total suspended solids (TSS) concentration as well as between TSS and COD. Such a relationship would help to continuously monitor and control quality of a wastewater discharge using turbidity measurement.