BOD5 estimation for pulp and paper mill effluent using UV absorbance

A novel method based on UV absorbance, is presented for estimating the BOD5 in pulp and paper mill effluent. This method could eventually be incorporated into an on-line sensor for BOD5 that is suitable for process control applications. Two streams, the reactor entrance and the final effluent, from two different mills were studied. One mill employed the Kraft pulping process, while the second mill was a thermo-mechanical one. The absorbance over the range 200-350 nm showed significant differences between the two mills. Because the two mills use very distinct processes, separate correlations were used to relate the absorbance to the BOD5 for both the mills. Results indicate that prediction of reactor entrance BOD5 was reasonable, whereas prediction of final effluent BOD5 was inaccurate, for both mills. Also studied was the effect of aeration on BOD5 results obtained at low BOD5 values for the Kraft mill.     

The risks from airborne asbestos in the urban environment

The objective of this full‐scale study is to determine the treatment performance of the activated sludge process for treating low strength municipal wastewater. The plant is located in Painesville, Ohio, and discharges its treated effluent into Grand River. The average plant wastewater flow was 3.43 MGD (million gallons per day). The plant performance was evaluated for a 12‐month period in 1989. The low strength municipal wastewater contained 104 mg/L TSS (total suspended solids), 105 mg/L BOD (biochemical oxygen demand), 17.76 mg/L TKN (total kjeldahl nitrogen), 9.66 mg/L NH₃‐N, and 3.90 mg/L P (phosphorus). The treatment performance after various degrees of treatment is as follows: primary treatment: 30% BOD and 54% TSS removal, secondary treatment: 97% BOD and 87% TSS removal, and tertiary treatment: 98% BOD and 98% TSS removal. The primary effluent contained 73 mg/L BOD and 48 mg/L TSS; the secondary effluent contained 3 mg/L BOD and 13 mg/L TSS; and the final effluent contained 2 mg/L BOD and 2 mg/L TSS. The effluent contained 0.22 mg/L NH₃‐N and 0.49 mg/L P, which were far below the US EPA standard of 10 mg/L BOD, 10 mg/L TSS, 1 mg/L NH₃‐N, and 1 mg/L P.     

Denitrification at various carbon to nitrogen ratios

The aim of this research was to examine whether the residual dissolved organic matter, remaining in chemically treated raw sewage would be able to satisfy the carbon demand in a denitrification process. In the first stage of research we investigated the effect of type and amount of organic substrate on denitrification efficiency. The critical weight ratios of methanol and sodium acetate to total concentration of nitrite and nitrate which enable the occurrence of complete denitrification were studied. It was found that when the concentration of the organic matter was expressed as BOD, a critical ratio of (mg BOD/mgΣNO_x-N) = 2.3 ensured 100% denitrification. Lower ratios decreased denitrification efficiencies proportionally. The same critical ratio was found when the chemically treated raw sewage was used as an available organic carbon source. Denitrification-nitrification process was also investigated by recirculating the nitrified effluent into the denitrification reactor, to which effluents from chemical treatment of raw sewage were fed to satisfy the carbon demand. The same critical ratio of BOD/ΣNO_x-N) = 2.3 was found. By increasing the recycling, nitrate concentration in effluent was decreased.     

河南桑坡村皮毛加工废水治理改扩建工程

桑坡村皮毛加工废水治理工程采用预处理/厌氧处理/两级生物好氧处理的主体工艺,原水COD为3 000～3 500 mg/L、BOD5为1 000～1 200 mg/L、SS为1 500～2 000 mg/L、NH3-N为30～50 mg/L、色度为500～600倍,处理出水BOD5、SS、色度达到<污水综合排放标准>(GB8978--1996)的二级标准,COD、NH3-N达到<焦作市2006年环境污染整治方案>的要求.     

Physico-chemical treatment of strong municipal wastewater

Direct chemical flocculation-clarification of strong new wastewater followed by adsorption on activated carbon has been investigated. The fate of specific organic components (low organic acids, carbohydrates, proteins, fats as well as BOD and COD) in the chemical treatment process was also studied. Excellent removals of phosphates, fats and suspended solids and a clear effluent were obtained in the chemical treatment. The clear ‘primary chemical’ effluent is, however, of high soluble organic content, the largest fraction being the soluble (low) organic acids and carbohydrates. Adsorption of the chemically treated wastewater on activated carbon gave a 60 per cent removal and a final effluent of a relatively high organic content including BOD. The high concentration of remaining organics is ascribed to poor adsorbability of the low organic acids anions on activated carbon.The significance of the findings for process considerations is discussed.     

A design model for nitrification on structured cross flow plastic media trickling filters

An empirical model has been developed to predict the effluent ammoniacal nitrogen concentration from structured cross flow plastic media trickling filters operated over the range of BOD loadings 0.12–0.38 kg/m³/day and ammoniacal nitrogen loadings of 0.06–0.23 kg/m³/day. The model gives good predictions based on 24‐h average effluent concentrations over a range of filter depths, organic and hydraulic loading rates. When incorporated with suitable hydraulic models, effluent ammoniacal concentration can be predicted through the diurnal range. The data gathering for the model included depth profiles on three filters. These have shown that at all but the very highest BOD loadings, nitrification commences from the very top of the filter in the presence of soluble BOD loadings previously thought to preclude the development of nitrifying biomass. Several reasons have been proposed to explain this, with the key argument being that the efficient oxygen transfer afforded by the media design is sufficient to satisfy heterotroph and autotroph oxygen demand simultaneously.     

Combined biological and ozone treatment of log yard run-off

Batch biological treatment of log yard run-off reduced biochemical oxygen demand (BOD), chemical oxygen demand (COD) and tannin and lignin (TL) concentration by 99%, 80%, and 90%, respectively. Acute (Microtox) toxicity was decreased over treatment, from an initial EC50 of 1.83% to a value of 50.4% after 48 h of treatment. Kinetics of biodegradation were determined using respirometry and fitted using the Monod and Tessier model. For the Monod model the maximum substrate uptake rate, and Ks values determined were 0.0038 mg BOD/mgVSS min, and 1.4 mg/L, respectively. The efficacy of ozone as a pre- and post- biological treatment stage was also assessed. During ozone pretreatment, TL concentration and acute toxicity were rapidly reduced by 70% and 71%, respectively. Pre-ozonation reduced BOD and COD concentration by < 10%, however a larger fraction of residual COD was non biodegradable after ozonation. Biologically treated effluent was subjected to ozonation to determine whether further improvements in effluent quality could be achieved. A reduction in COD and TL concentration was observed during ozonation, however no further improvement in toxicity was observed. Ozonation increased BOD by 38%, due to conversion of COD to BOD.     

CASS/MBR工艺在人造板厂废水处理工程中的应用

昆明超冠人造板厂位于国家级风景名胜区附近,每天产生的废水仅50 m3,但成分复杂,含有纤维素、SS、泥垢、溶解性有机污染物等,废水COD为160～200 mg/L、BOD5为80～100mg/L、SS为200～250 mg/L,采用CASS/MBR工艺处理后,出水水质达到《城镇污水处理厂污染物排放标准(》GB 18918—2002)一级A标准。该工程已通过环保部门的验收,运行稳定,处理出水回用于冷却用水、绿化用水。该工程投资约20万元,运行费用为0.92元/m3,处理水回用后每年节约水费为5万多元。     

Pilot Scale Aerobic Sequencing Batch Reactor for Pig Waste Treatment

A n existing aetated lagoon treating piggery waste was converted into an aerobic sequencing batch reactor (SBR). After the commissioning period, the SBR plant treated piggery wastewater containing BOD and suspended solids (SS) concentrations of 2881 mg/l and 1419 mg/1 respectively, producing an effluent having an average BOD and SS of 18.7 mg/1 and 12.3 mg/1 respectively. The volumetric loadings on the SBR and the process were similar. However, the SBR process operated at a lower mixed liquor suspended solids (MLSS) concentration and shorter sludge retention period. Although the capital and operating costs of the SBR are higher than for the aerated lagoon, the simplicity of operation, the high BOD and SS removal efficiency, and the small land requirement make this type of process an attractive treatment option, particularly in places where land supply is limited and expensive.     

An investigation of organic compounds in night soil and the treated water by gas chromatography-mass spectrometry

Although the rates of removal of BOD and other indicators have been studied for the evaluation of night soil^* treatment plant, there is no report about organic compounds. In order to identify trace amounts of organic compounds in night soil treatment plant at each process stage, the organic compounds in the night soil and in the treated water were subjected to anaerobic methods and analyzed by gas chromatography—mass spectrometry. Cholesterol and coprostanol as fecal sterols, indoles as odor substances and dichlorobenzene, cresol and phenol as disinfectants used in toilets were identified in the sample of night soil. As a result of anaerobic treatment the fecal sterols were degraded, oxindole remained, and phenylacetic acid was identified as a metabolite from tryptophan. These organic compounds were completely degraded by the aerobic treatment when phthalates and adipate were identified in the effluent.     

Correlations of performance for activated sludge using multiple regression with autocorrelation

A method is developed to correlate activated sludge response variables, such as SVI, effluent volatile suspended solids or effluent BOD, with state variables such as F/M ratio, influent BOD, dynamic sludge age, etc. The method is based on multiple linear regression with autocorrelated errors. The method was applied to three data sets from two full-scale activated sludge plants; one a regional municipal utility, the other an industrial facility. Highly statistically significant models were found which could explain 65–82% of the variability in effluent total oxygen demand, 22–60% in effluent volatile suspended solids and 48–88% in sludge volume index. It was only necessary to model up to second order lags. The models were tested for bias using different data sets and produced correlation coefficients between predicted and observed values as high as 0.96. These results show that useful predictive relationships can be developed for full-scale activated sludge processes. The methods could be used to develop a range of automatic process control schemes.     

Treatment of landfill leachate by combined aged-refuse bioreactor and electro-oxidation

Two-stage aged-refuse bioreactor (ARB) was applied to treat landfill leachate in Shanghai Waste Laogang Disposal Plant. The removal efficiencies of chemical oxygen demand (COD), biological oxygen demand (BOD), total organic carbon (TOC), total nitrogen (TN) and ammonia nitrogen (NH(3)-N) of landfill leachate treated by the two-stage bioreactor system were 98.5%, 99.9%, 98.0%, 64.2% and 99.9%, respectively. The COD and BOD in the second stage effluent were 239 and 7 mg l(-1), respectively. Thus three types of electrolysis were employed to further treat the second effluent, undivided electrolysis (UDE), divided electrolysis (DE) with Ti/PbO(2) cathode and DE with gas diffusion cathode. All electrolysis processes possessed good color removal effect, while the DE with gas diffusion cathode had the best TOC removal effect. The optimum electrolysis time of leachate was 30 min. The TOC removal efficiencies were 51.4% and 39.7% in anolyte and catholyte, respectively, after 30 min electrolysis at 5 V. In addition, the DE with gas diffusion cathode showed the least energy consumption of 9.8 k Whm(-3) at 30 min. The organic pollutants in the leachate were analyzed through a gas chromatography coupled with mass spectrometry (GC-MS) system. Through the two-stage ARB, the species and concentrations of organic pollutants in landfill leachate reduced greatly. Several chlorinated organic compounds were detected in the effluent after the UDE and the anolyte of the DE. In addition, the concentration of absorbable organic halogens (AOX) increased greatly during the electrolysis. Hence, careful consideration should be given in the application of electro-oxidation into the treatment of chloride-containing wastewater.     

The role of benthic films in the oxygen balance in an East Devon river

A portable respirometer has been used to measure oxygen uptake and production rates, by fixed and suspended organisms in an East Devon river which receives papermill effluent. Benthic respiration dominates the oxygen balance in the stretch most affected by the effluent and increases the effective BOD decomposition rate by a factor of up to 12: Values of decomposition rate of 3.5–4.5 (day⁻¹) have been measured in the stream.     

Electrochemical treatment of cigarette industry wastewater: feasibility study

The electrochemical treatability of wastewater from the cigarette industry has been investigated in this paper using cast iron electrode. The treatment efficiency was monitored in terms of COD, BOD and suspended solids concentration. The cast iron anode was found effective in treatment of the above-mentioned wastewater. About 56% of COD and 84% of BOD removal was observed at 3.5 A current for 5 h of electrolysis. The effect of increase in surface area of anode reduces electrolysis time and also energy consumption per kg of COD removal. The treated effluent was subjected to chemical coagulation studies using Ca(OH)2 as coagulant. The final treated effluent was found to confirm the stipulated standards for safe disposal into surface water bodies (Indian Standards). It was concluded that the electrochemical treatment followed by chemical coagulation could be opted as an alternate treatment scheme for the present industry.     

Effect of average flow and capacity utilization on effluent water quality from US municipal wastewater treatment facilities

There is increasing interest in decentralization of wastewater collection and treatment systems. However, there have been no systematic studies of the performance of small treatment facilities compared with larger plants. A statistical analysis of 4 years of discharge monthly report (DMR) data from 210 operating wastewater treatment facilities was conducted to determine the effect of average flow rate and capacity utilization on effluent biochemical oxygen demand (BOD), total suspended solids (TSS), ammonia, and fecal coliforms relative to permitted values. Relationships were quantified using generalized linear models (GLMs). Small facilities (40 m³/d) had violation rates greater than 10 times that of the largest facilities (400,000 m³/d) for BOD, TSS, and ammonia. For facilities with average flows less than 40,000 m³/d, increasing capacity utilization was correlated with increased effluent levels of BOD and TSS. Larger facilities tended to operate at flows closer to their design capacity while maintaining treatment suggesting greater efficiency.     

Construction and Operation of a Submerged Aerated Filter Sewage-Treatment Works

The capacity of the sewage-treatment works at Silchester in Hampshire has been enhanced and the effluent quality improved to a high standard by the installation of a new submerged biological aerated filter plant. Ten prefabricated steel submerged aerated filters reduce BOD and fully nitrify settled domestic sewage from a population equivalent of 20 000.
Comprehensive operating data are presented to demonstrate the ability of single-stage submerged downflow aerated biological filters to produce a nitrified effluent. The final effluent quality remains consistently within consent limits at 4.8 mg/l BOD, 7.0 mg/l SS and 0.5 mg/l NH₃-N, all 95 percentiles. (Consent 7 mg/l BOD, 25 mg/l SS, and 5 mg/l NH₃-N, 95 percentiles.)
Data are presented on total coliform and E. Coli concentrations through the filter plant, showing better than 3 log reductions in the effluent.     

Effects of carbon dioxide deficiency and metal toxicity on biological oxygen demand

In this study, the effects of carbon dioxide (CO₂) deficiency on the biological growth under respirometric conditions, first‐ and second‐order biological oxygen demand (BOD) progressions using two different BOD measurement techniques and metal toxicity effects on the respirometric BOD are investigated. The effects of CO₂ deficiency in the growth of bacteria and related effects on the first‐ and second‐stage BOD progressions are investigated using various media with respirometers in comparison with the BOD dilution method. CO₂ deficiency causes significant retardations on the growth of bacteria and the second‐stage respirometric BOD values are suppressed. CO₂ seems to be an essential nutrient for the growth of microorganisms and for the oxygen uptake progressing rates. HgCl₂, HgSO₄, CuSO₄, K₂Cr₂O₇, ZnSO4 and Al₂(SO₄)₃ inorganic metal compounds cause significant retardations in the respirometric BOD values obtained from a synthetic autotrophic medium. Effects are found to be dependent on the applied concentrations of these chemicals in the medium.     

Complete physico-chemical treatment for coke plant effluents

Naturally found coal is converted to coke which is suitable for metallurgical industries. Large quantities of liquid effluents produced contain a large amount of suspended solids, high COD, BOD, phenols, ammonia and other toxic substances which are causing serious pollution problem in the receiving water to which they are discharged. There are a large number of coke plants in the vicinity of Jharia Coal Field (JCF). Characteristics of the effluents have been evaluated. The present effluent treatment systems were found to be inadequate. Physico-chemical treatment has been considered as a suitable option for the treatment of coke plant effluents. Ammonia removal by synthetic zeolite, activated carbon for the removal of bacteria, viruses, refractory organics, etc. were utilized and the results are discussed. A scheme has been proposed for the complete physico-chemical treatment, which can be suitably adopted for the recycling, reuse and safe disposal of the treated effluent. Various unit process and unit operations involved in the treatment system have been discussed. The process may be useful on industrial scale at various sites.     

污水处理中CASS工艺活性污泥培养与驯化

通过重庆市大渡口污水处理厂工程,重点介绍了工程调试中活性污泥培养与驯化的情况。实践表明,采用接种法培养驯化活性污泥20d就能完成污泥培养驯化,COD、BOD、SS的去除率分别为77.8%～88.3%、88.4%～95.9%、83.1%～92.1%,各项出水水质指标达到或优于设计目标。最后对培养驯化过程中出现的泡沫、进水BOD低营养源不足、滗水后期有微弱曝气和污泥回流、排泥等问题提出了相应的解决措施。