Water / Wastewater Treatment
Treating High-Strength Ammonia Wastewaters ACWAServices’ (UK) innovative AMTREAT®
activated sludge process, a dedicated, cost-effective system for treating high-strength ammonia wastewaters, enables utilities
to meet increasingly onerous discharge consent requirements for ammonia and total nitrogen. High strength ammonia wastewaters are typically generated in sludge treatment processes. The AMTREAT®
system is designed to operate at its optimum level when
the influent liquor temperature is 25ºC and is effective between 20ºC and 35ºC, so it is ideal for the warm liquors that the sludge drying process generates. The relatively low temperature used gives the system a real advantage over competitor systems that require temperatures of 30ºC to 40ºC to work efficiently, generating significant energy penalties.
The AMTREAT® system can achieve full nitrification of effluent streams with ammonia concentrations of up to 3000mg/l, with typical ammoniacal nitrogen removal
rates in excess of 97%. Although some competitor systems claim 25% energy savings by producing NO2 (nitrite) rather than the NO3 (nitrate) created in the full nitrification process, any cost savings are offset by the considerably larger power expenditure required to ensure the contents of the large tanks remain mixed for the longer retention time required.
ACWA Services Wastewater Process Manager, Dr Sarah Collins warns of a further issue: “In systems that claim as much as 30% less sludge production, the amount of sludge produced is likely to depend more on
carbonaceous removal than the production of the bacterium, Nitrobacter (converting NO2 into NO3) – if less sludge is produced as a result of producing NO2, it would be infinitesimal as the amount of sludge produced from Nitrobacter is negligible in the overall picture.” A typical AMTREAT®
system consists of a balance tank with mixing system, a liquor blending system, followed by an anoxic tank to provide denitrification upstream of the AMTREAT®
, some systems also require an organic source such as methanol or glycol for denitrification. However the large anoxic tanks required to provide the necessary 12 hours’ retention time compared to the much smaller retention time needed in the more effective AMTREAT® system create further cost implications. As Dr Collins points out: “In most applications it is considered beneficial to recycle nitrate as it supplements the oxygen input into the plant’s aeration system.”
NaOH to control pH, but this slim advantage is completely wiped out by the cost of the much larger anoxic tanks.” Unlike AMTREAT®
The reactor itself is designed as a fully-mixed vessel, in which carefully-controlled conditions ensure the optimum amount of nitrifying bacteria are present in suspended aerobic cultures. Again, the careful choice of sizing of the reactor ensures that even with similar levels of dissolved oxygen to competitor products, the smaller tanks’ energy usage ensures costs are considerably lower. A proportion of the mixed-liquor suspended solids (MLSS) and return activated sludge (RAS) are recycled to the anoxic tanks. Solids separation is achieved utilising conventional secondary clarifiers. Some competitor
technologies do not provide a settlement tank for solids removal, which presents insurmountable challenges in meeting suspended solids limits. AMTREAT®
also provides benefits after a shutdown, as the nitrifying bacteria would enable an initial extra capacity. Reader Reply Card No 31 uses sodium hydroxide for pH control. Competitors utilising CO2 stripping, which uses air and reduces the need for NaOH, are expending valuable air and consequently energy. The AMTREAT® system reactor. The anoxic tanks are
optimally sized to ensure adequate denitrification without the severe cost penalties incurred by larger tanks. Dr Collins notes: “There is a careful balance between achieving denitrification and the size of the tank required. The AMTREAT®
anoxic tanks are designed to ensure that this delicate balance is optimised. Larger tanks will achieve greater denitrification and release more alkalinity to the system, which slightly reduces the need for
New Innovative Microscreen Filters
New Biofilm Process for Biological Sewage Treatment
The MOFIX process is based on biofilm technology and has been developed and tested in a joint research project of GEA 2H Water Technologies (Germany) and the Martin-Luther University Halle-Wittenberg. A pilot plant was operated and tested in Halle (Saale), before being transferred and built up in Tunisia. Since 2008 a village of 200 inhabitants has used the plant for full biological treatment. The concept has meanwhile been implemented in several plants in Germany including a large well-known oil processing site in Germany.
MOFIX (MOving bed + FIXed bed) is a process combining both biofilm technologies. A special feature of this application is the denitrification in a moving bed as a first process step. Here random media is used a biofilm carrier. In the second step the final BIOD reduction is carried out in a submerged fixed bed, followed by an intermediate clarifier which eliminates excess sludge. Now the nitrification reactor follows, consisting of a 2-3-stagfe cascade equipped with a BIOdek fixed beds. A final clarifier removed solids before the water exits.
The denitrification reactor is equipped with Random Media BCN. A special agitator mixes water and the random media. Although moving slowly, the
agitator develops a high stirring power with only low shearing forces, thus conserving the biofilm on carriers. In the aerated zones only fixed bed consisting of BIOdek®
structured packing is installed, because of the advantages of fixed beds. For the carbonaceous
oxidation step BIOdek vertical flow fills type 2H KVP provide optimum features for discharge of the excess sludge. For nitrification after intermediate clarification high specific surfaces of the BIOdek® Intermediate and final clarification are equipped with TUBEdek®
channels giving a multiplication of sedimentation areas in a small volume even with high recirculation rates. Reader Reply Card No 32 fills provide high efficiency. tube settlers. An efficient sludge removal is achieved by the chevron shaped TUBEdek®
Hydrotech (Sweden), a Veolia Water Solutions & Technologies company launches the HSF 2600, the new generation of microscreen filters. This range of discfilters features a huge filtration area and is the most cost-efficient machine for municipal water, industrial water and wastewater treatment.
Built upon the highest standards in discfilter
technology, HSF 2600 uses a combination of high quality materials and innovative solutions, cutting down on energy and increasing efficiency.
The water to be treated flows into the filter
drum. A patented design leads then the water into the disc segments. The flat filter panels in each disc segment catch the solids and divert them to a collection area, allowing filtered water to pass through.
Hydrotech’s filters panels unique design offer a long life span and superior cleaning when backwashing. They minimise power and backwash water consumption that significantly reduces carbon footprint.
By building machines with a larger capacity that take up a smaller area, Hydrotech filters reduce total installation costs and enable a bigger water quantity to be filtrated, while using fewer machines.
Reader Reply Card No 33
Reader Reply Card No 34
www.pollutionsolutions-online.com • Annual Buyers’ Guide 2011
9
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
