Biological aerated filter treatment of coking wastewater-BAF, BAF, coking wastewater – water industries

Overview Coking wastewater is a high COD, high phenol value, high ammonia treatment of challenging industrial organic wastewater. Given that the 80s of the 20th century, more than the domestic coking wastewater by two biochemical approaches, extended aeration technique, strong biochemical strategies (such as biological iron, biological activated carbon) and other strategies, in which A / O approach (anaerobic 1 aerobic activated sludge) treatment was finest, but the A / O strategy larger initial investment and operating costs, 1m3 of water expenses about 7.4 yuan to deal directly with the general coking enterprises unbearable.

BAF (BiologicalAeratedFilter, referred to as BAF) is the contact with oxygen in biological Chemical business Art based on the introduction of drinking water treatment filter suggestions emerged as an aerobic Membrane Treatment Technology. The simple principle is the primary treatment is based on the primary treatment, with granular Filler The growth of biofilm and its attachment to deal with media, give full play to the role of microbial metabolism, the role of physical filtration, membrane and fill the role of the physical Absorption and bio-reactor, multi-stage predation, in the exact same unit of pollutant removal reactor . The procedure has high volumetric loading, hydraulic loading large, hydraulic retention time is short, very good effluent top quality, little size, much less investment in infrastructure, energy consumption and operating costs low. This study will examine the application of coking wastewater treatment refractory feasibility of efficient treatment of coking wastewater to seek new techniques.

1 test techniques and supplies Water sources and water high quality

1.1 Test wastewater from Ma On Shan Steel Company coking plant, the water high quality refers to Table 1

Table 1 Coking Wastewater High quality 1.2 Experimental Materials BAF reactors create cylindrical plexiglass column, high-1.55m, diameter .11m, volume 14.7L, built 8.7L Lytag Filter Media , Filter-storey 1.1m. Way to the stream utilizing water (bottom water), plates, long-handled water filter head cloth, the upper drainage, sintered sand core aeration (YL-888 sort gas Pump ), 2 BTOO a SOM-based present pump water.

Lytag filter parameters: diameter of three to 5mm, the packing density of .89g/cm3, broken rate of .07%, certain surface location of 4.8m2 / g, porosity 35%, the wear rate of 5.3% hydrochloric acid soluble rate of .5%. BAF structure indicated in Figure 1.

1.three procedure and test methods

1.3.1 Procedure Test procedure shown in Figure 2. Coking wastewater sedimentation tank by adjusting the pump by the constant injection of BAF bottom of the skillet following the very first filter into the filter layer. At the exact same time from the pump to the filter layer aeration, the water after backwashing pool (storage pool) efflux. Backwash time intervals, combined with air and water backwash. Is: very first gas recoil 5min, and then start the water pump, air and water backwash at the very same time 5min, the final water rinse 5 – 8min. Backwash water with reactor (ie, Figure 2 backwash pool). Backwash off the biofilm, sludge and other impurities with the backwash water back to the regulator, sedimentation tanks, sedimentation basins, sludge efflux by the set.

1.three.2 operating parameters Air to water ratio of .5 to 1 backwash cycle 7 ~ 8d, the joint air and water backwash, air, water backwashing strength was 5 1 8sL / (s * m2), anti-washing time of 15 a 18min hydraulic load 1.05 ~ 2.5rn3 / (m2? h).

1.3.3 Water Sampling Strategy

Every 1h, respectively, and in regulating the sedimentation pool backwash twice the sampling, sample water 200mL, and mix the a variety of water samples by mixing the sample population sample (a total of 6 times 1200mL), this can be as a lot as possible remove or stay away from a sampling error due to chance, sampling location surface Department under 3cm.

1.4BAF culture biofilm BAF biofilm culture technique with continuous feeding. Fundamental operation is: Maanshan Iron &amp Steel coke plant will be taken from activated sludge wastewater treatment plant soon after appropriate stirring continuously adding Taomi Shui adding aeration reactor and make continuous progress Taomi Shui three days following the cessation of sludge increases, water use diluted white inflow of low coking wastewater and adding a small quantity of potassium hydrogen phosphate to boost phosphorus levels in wastewater, control the reactor mixture was alkaline, following 20 days on the growth of the thin filter filter a layer of biofilm. Microscopic examination of biofilms under the microscope off the results shown in Figure three, Figure 4 shows that the biofilm has a lot of ciliates protozoa such as Paramecium, roaming insects, beetles and other beans. The directions of the growth of mature biofilm protozoa marks. Meanwhile reactor wastewater COD)) removal efficiency of 70%, at this time that the success of biofilm culture, can be test conditions.

1.five Water Good quality Analysis Water high quality analysis method based on “Water and Wastewater Monitoring Analysis Approach,” (4th edition), CODCr was measured with potassium dichromate ammonia was determined by distillation of a Nessler’Sreagent pH measured by electrode approach phenol was determined by 4-amino-antipyrine a direct method cyanide with isonicotinic acid Spectrophotometric a border wow.

2 Outcomes and Analysis 2.1 hydraulic load and the relationship between the removal of COD))

Hydraulic load is directly related to the size of Sewage In the reactor and carrier biofilm contact time. The smaller the value of water and the biofilm reaction time longer, the far better. CODCr influent concentration of 820mg / L when, BAF under various hydraulic loading CODcr coking wastewater removal effect shown in Figure five. BAF can be seen from Figure 5 on the coking wastewater with high organic matter removal, when the hydraulic load is .05 of a .2m3 / (m2 “h) time, COD. Removal rate reached 90%, and the water concentration of about CODcr to 220mg / L, to GB13456-92 national secondary emission standards.

2.2 phenol, cyanide removal BAF on the coking wastewater phenol, cyanide removal in Table 2. As can be observed from Table 2, when the average hydraulic loading .12m3 / (m2 * h) time, BAF phenol wastewater, average removal rates of cyanide up to 980% and 96%, and water to the GB13456-92 countries 1 emission standards.

Figure 6BaF ‘on the coking wastewater removal of NH3-N

2.three Removal of ammonia nitrogen

Influent NH3-N was 160mg / L when, BAF under various hydraulic loading on the coking wastewater removal efficiency of NH3-N shown in Figure 6. Can be seen from Figure 6, BAF coking wastewater removal of NH3-N much less successful, when the hydraulic loading of .1m3 / (m2 * h) time, BAF on NH3-N removal efficiency is only 45%. Meanwhile, with the hydraulic load growth, the removal rate decreases, when the hydraulic load to .25m3 / (m2 * h), the effluent concentrations than influent concentration rather huge. Mainly due to

Reactor CODCr, NHS-N concentration was higher, inhibited the metabolism of nitrifying bacteria in wastewater, and with the decomposition of nitrogenous organic matter, resulting in effluent NH3-N concentration.

three Conclusion