The biodegradability of two primary alcohol ethoxylate nonionic surfactants under practical conditions,and the toxicity of the biodegradation products to rainbow trout

A field trial has been performed to measure the biodegradability of two typical alcohol ethoxylate nonionic surfactants, “Dobanol” 45-7 and “Dobanol” 45-11, by dosing them to biological filters in a mixture with domestic sewage. Influent levels were 10 and 25 mg l^?1 of each surfactant and 96–98% degradation was achieved within a temperature range of 5–10°C. The surfactants had no adverse effects on the filters in terms of the usual sanitary parameters (BOD, COD, TOC and ammoniacal nitrogen). Tests on the effluents indicated no residual acute lethal toxicity to rainbow trout Salmo gairdneri).     

Removal of nitrate from effluent following discharge on surface water

The loss of nitrate nitrogen over a 800-m long reach of canal was studied in a field experiment during a 20-days period. The nitrate originated mainly from sewage effluent. Fifty-six percent of the nitrate had disappeared during its flow through the 800-m long reach, where the average retention time was 1.7 days. The average rate of nitrate disappearance during the 20-day period was 913 mg NO₃⁻-N m⁻² day⁻¹. Laboratory experiments with undisturbed water-sediment profiles from the canal showed that the disappearance of nitrate was caused mainly by denitrification in the sediment. Increased knowledge of this phenomenon may lead to an effective and cheap means in inducing denitrification.     

Microbiological aspects of fish grown in treated wastewater

Tilapia, common carp and silver carp were reared in treated domestic wastewater. The most sensitive to this environment was the silver carp, followed by common carp and tilapia. In healthy clean fish, bacteria were not found in the blood or the muscles. They were present in small numbers in various organs and in concentrations of 10⁶–10⁷ g⁻¹ in the digestive tract content. In fish exposed to treated wastewater for the entire growing period, bacteria were found in the muscles. The number of bacteria recovered from various organs ranged between 10⁴–10⁶ g⁻¹ and their concentration in the digestive tract content was 10⁸–10⁹ g⁻¹. The number of bacteria in the pond water determined the presence and concentration of bacteria in the fish. The number of bacteria that caused their appearance in the muscles of fish has been named the “threshold concentration”. Considering the public health aspects, fish can be reared in treated wastewater provided the bacteriological quality of the water is compatible with the “threshold concentration” levels of the fish grown in the ponds. The suitability of E. coli (fecal coliform bacteria) as indicators for the bacteriological quality of fish grown in wastewater-fed ponds is examined.     

Degradation of phenol in wastewater in an upflow anaerobic sludge blanket reactor

Phenol in wastewater could be effectively degraded in an upflow anaerobic sludge blanket (UASB) reactor. With a 1:1 effluent recycle ratio, over 97% of phenol was removed at 37°C and pH 6.9-7.5 with 12 h of hydraulic retention time for phenol concentration up to 1260 mg·1⁻¹, corresponding to 3000 mg·1⁻¹ of chemical oxygen demand (COD) and a loading rate of 6 g-COD·1⁻¹·day⁻¹. The seed sludge took about 7 wk to develop the phenol-degrading capability which was sensitive to shocks. The bioactivity deteriorated readily when the granules were exposed to sudden changes of temperature and loading. Although the damage was not permanent, the recovery of bioactivity was gradual and lengthy. At 6 g-COD·1⁻¹·day⁻¹, each gram of granules was able to convert 0.49 g of COD into methane daily. On the average, about 94.7% of the total COD removed was converted to methane, while the rest was converted to biomass with a net yield of 0.038 g-VSS·(g-COD-removed)⁻¹. Electron micrographs show that the granules were composed of, among others, Syntrophus buswellii-, Methanothrix-, Methanospirillum- and Methanobrevibacter-like bacteria.     

Concentrations of nitrilotriacetate and certain metals in Canadian wastewaters and streams: 1971–1975

At 13 Ontario cities, representing a variety of populations and sewage treatment processes, grab samples were taken from the sewage treatment plant influent and effluent and from the receiving stream above and below the sewage outfall. The samples, taken once each month from November 1971 to March 1975 were analyzed for nitrilotriacetate (NTA), 9 metals, and phosphorus. From April 1971 to January 1973 household detergents in Canada contained an average of 6% NTA; after March 1973 they contained 15%. This increased usage of NTA was reflected in the NTA content of sewage influents, which rose from a median level of 1.3 mg l⁻¹ before the change to 3.2 mg l⁻¹ after the change. NTA levels in sewage effluent also increased somewhat, but much of the NTA disappeared in the sewage treatment processes. Even with the increased usage of NTA, the receiving streams below the sewage outfall contained only low levels of NTA: 97% of all samples during this period contained less than 0.5 mg l⁻¹, and the median concentration was 0.05 mg l⁻¹. Phosphorus concentrations in the sewages decreased at the time detergent compositions changed. Comparison of metal concentrations before and after the change, as well as metal-NTA correlation coefficients, failed to show clear evidence of an association between NTA concentration and metal concentration.     

The 10 m3 h−1 rim-nut demonstration plant at West Bari for removing and recovering N and P from wastewater

The RIM-NUT, a new ion exchange-precipitation process for removing and recovering ammonium and phosphate ions from wastewater, has been tested on a 10 m³ h⁻¹ demonstration plant for tertiary treatment of West Bari domestic effluent. Natural zeolite clinoptilolite and a porous strong base resin, regenerated in a “closed-loop” fashion with 0.6 M neutral NaCl, ensure ≥90% removal of both nutrient species. Nutrients are precipitated from resin eluates as MgNH₄PO₄, a premium quality slow-release fertilizer.     

Comparison of molecular markers to detect fresh sewage in environmental waters

Human-specific Bacteroides HF183 (HS-HF183), human-specific Enterococci faecium esp (HS-esp), human-specific adenoviruses (HS-AVs) and human-specific polyomaviruses (HS-PVs) assays were evaluated in freshwater, seawater and distilled water to detect fresh sewage. The sewage spiked water samples were also tested for the concentrations of traditional fecal indicators (i.e., Escherichia coli, enterococci and Clostridium perfringens) and enteric viruses such as enteroviruses (EVs), sapoviruses (SVs), and torquetenoviruses (TVs). The overall host-specificity of the HS-HF183 marker to differentiate between humans and other animals was 98%. However, the HS-esp, HS-AVs and HS-PVs showed 100% host-specificity. All the human-specific markers showed >97% sensitivity to detect human fecal pollution. E. coli, enterococci and, C. perfringens were detected up to dilutions of sewage 10⁻⁵, 10⁻⁴ and 10⁻³ respectively. HS-esp, HS-AVs, HS-PVs, SVs and TVs were detected up to dilution of sewage 10⁻⁴ whilst EVs were detected up to dilution 10⁻⁵. The ability of the HS-HF183 marker to detect fresh sewage was 3-4 orders of magnitude higher than that of the HS-esp and viral markers. The ability to detect fresh sewage in freshwater, seawater and distilled water matrices was similar for human-specific bacterial and viral marker. Based on our data, it appears that human-specific molecular markers are sensitive measures of fresh sewage pollution, and the HS-HF183 marker appears to be the most sensitive among these markers in terms of detecting fresh sewage. However, the presence of the HS-HF183 marker in environmental waters may not necessarily indicate the presence of enteric viruses due to their high abundance in sewage compared to enteric viruses. More research is required on the persistency of these markers in environmental water samples in relation to traditional fecal indicators and enteric pathogens.     

Effect of temperature on the anaerobic thermophilic conversion of volatile fatty acids by dispersed and granular sludge

The effect of temperature on the rate of volatile fatty acid (VFA) conversion by thermophilic methanogenic sludge, cultivated at 55°C, was studied using both batch activity tests and continuous flow experiments. The temperature dependence of acetate conversion in the range between 37–70°C could be described by an Arrhenius derived model when dispersed sludge with a low specific activity was used. For this sludge the optimum acetate conversion rate was found at 65°C. However, the maximum acetate utilization rate was not affected by temperature in the range between 50°C to 65°C when granular sludge with a high specific methanogenic activity was used. Crushing the granules led to a 2 to 3 fold increase in the maximum activity at 60–65°C, indicating that the conversion rate was very likely limited by the diffusion rate of acetate into the granules. Similar results were obtained with butyrate as the substrate. The temperature dependence of the crushed granules was similar to that of the less active dispersed sludge. In contrast, the thermophilic propionate oxidation rate was highest with the intact granular sludge while a similar temperature dependence was found for both the granular and dispersed sludges. The affinity for VFA increased with decreasing temperature. This phenomenon was most pronounced for the granular sludge. The thermophilic treatment of a VFA-mixture in a UASB reactor appeared to be only slightly affected by temperature when moderately low loading rates were applied, i.e. 20 kg COD·m⁻³·d⁻¹. However, temperature had a strong effect applying loading rates of 40–90 kg COD·m⁻³·d⁻¹ accompanied with high effluent VFA concentrations. The results reveal a high thermostability of the thermophilic wastewater treatment process in the range 45–60°C if “high-rate” reactors with a granular sludge bed are used.     

Calcium carbonate deposition in Ca2+ polluted Onondaga Lake,New York,U.S.A.

Seasonal and long-term trends in the rate of calcium carbonate (CaCO₃) deposition are documented for Ca²⁺ polluted Onondaga Lake, New York. These observations are based on particulate inorganic carbon and particulate calcium analyses of sediment trap collections, made weekly over the May-September interval for 10 years. Continuous deposition of CaCO₃ was evident for the monitoring period of all 10 years. The average rate of CaCO₃ deposition for the deployment interval decreased from about 0.196 to 0.082 mol·m⁻²·d⁻¹ following the closure of the industrial source of Ca²⁺ pollution. This decline was generally consistent with the reductions in Ca²⁺ loading and lake Ca²⁺ concentrations over the same period. The prevailing rate of CaCO₃ deposition in Onondaga Lake remains substantially higher than the rates documented for three other hardwater lakes in the literature. Calcium carbonate is the primary component and principal regulator of the dynamics of total solids deposition in the lake.     

Formation and properties of sediments in constructed wetlands for treatment of domestic wastewater

Sediments formation and biogeochemical properties were studied in an experimental constructed wetland site in Ukraine (“Bioplato”) for treatment of domestic effluents. The wetland, with a capacity of 50 m³ d^? 1 of wastewater, consists of vertical and horizontal filtrations units with fine gravel, middle and coarse sand, a subsurface flow unit with natural wetland soil applied, and a septic tank and sludge-drying field. Macrophytes, reed (Phragmites australis), cattail (Typha latifolia) and a number of sedge species (Carex spp.) were planted in the area and dominate the average cover of 85–90%. Treatment efficiency for BOD₅ and suspended solids was 93–96%, for COD – 82%, for nutrients – 27–50%, and for pathogenic microorganisms 99.3–99.6%. Sludge was sampled at each unit followed by standard laboratory analyses of its main characteristics: total organic carbon (TOC), total nutrients (N, P), contents of trace elements, abundance of pathogenic microorganisms, and general toxicity. Results confirmed that the top layer of sludge from each unit of wetland could be used as a source of fertilizers for grain and leguminous crops.     

Removal of indigenous rotaviruses during primary settling and activated-sludge treatment of raw sewage

An eight month study of indigenous rotavirus removal during primary settling and activated sludge treatment of raw sewage was made in a plant in Houston, Texas treating 1.5 million gal day⁻¹. An average reduction of 44–55% was obtained by primary settling and a 93–99% reduction was achieved in final chlorinated effluents. Composite sampling at 1 h intervals over a 24 h period indicated average removals of 85% compared to a misleading 6% indicated by one set of grab samples of raw sewage and effluent collected simultaneously. Quantification of rotaviruses was made by immunofluorescent foci counts 24 h after addition of sample concentrates to coverslip cultures of fetal rhesus kidney cells. Rotaviruses varied from 40–5101⁻¹ of raw sewage and from 0 to 25 in the final chlorinated effluent.     

Long-term phosphorus budgets and an examination of a steady-state mass balance model for central Ontario lakes

The objective of this study was to evaluate, modify if necessary, and calibrate a mass balance steady-state total phosphorus (TP) model for use in the Precambrian Shield area of Ontario. Hydrologic data, TP mass balances and lake concentrations data were collected between June 1978 and May 1992 from seven oligotrophic and oligomesotrophic lakes located on the Precambrian Shield in central Ontario. Two of the lakes (Dickie and Harp) had substantial shoreline development; four lakes had alkalinities <25 μ eql⁻¹. The gross settling or loss coefficient, v, was underestimated when internal load was ignored. Long-term mean v ranged about three-fold, from 4.7 m yr⁻¹ in Plastic Lake to 13.7 m yr⁻¹ in Dickie Lake with an average for six lakes of 7.9 m yr⁻¹. The exception was Harp Lake where v was 23.2 m yr⁻¹. The difference in v between heavily developed Dickie and Harp Lakes may have been due to the unusually thick glacial tills in the Harp catchment and their likely ability to retain at least some of the TP from septic effluent. The current inability to predict septic TP retention rates by soils/tills, the highly variable nature of soils/tills, and the decades required to reach equilibrium after installation leave environmental managers with little choice but to apply the “precautionary principle” to ensure adequate protection of inland recreational waters and assume that soils do not retain septic TP. There was no evidence that enhanced sedimentation of TP (“oligotrophication”) occurred in any of the three most acidic lakes. In fact, losses via sedimentation were lowest in these lakes. Average retention, R ((input-output)/input) of TP during the ice-free months of May to November was much higher than average R in winter (December–April) in all lakes. Lack of wind-induced mixing, low biological activity and thermal stratification caused by ice cover make it more likely that stream loads are discharged directly from lakes during winter. Seasonal variation in retention suggests that R and v should be higher in warmer climatic zones. There may be no globally valid v, although the data presented here suggest that a regionally applicable estimate of v may be appropriate. The model should only be calibrated with a long-term data set and should be only used to predict long-term, average responses to changes in average TP loading.     

Time-trends of metals and organic contaminants in sewage sludge

The occurrence of chemicals in sludge from sewage treatment plants (STPs) is of concern for human health and the environment. Legislations and regulations are put in place to minimize the release of harmful chemicals into the environment and arable land, e.g. via application of sewage sludge. Temporal trends analysis of sludge contaminants can be used to assess the effectiveness of such actions. Such analyses can be performed retrospectively, using sludge stored in environmental specimen banks, to investigate new or emerging environmental contaminants. The present study provides data from time-trend analyses of metals, persistent organic pollutants, pharmaceuticals, personal care products, and other organic compounds in sludge from Swedish. The analysis showed that sludge is a suitable matrix for time-trend studies and it can take on average 12 years (range, 5-26 years) to track an annual change of ±10% (with a power of 80%). Statistically significant trends were found for 18 out of the 77 compounds subjected to analysis, of which 75% showed decreasing trends. Triclosan and the antibiotic norfloxacin followed the same trend as the national recorded usage and decreased annually by 65% and 60%, respectively. The opposite was true for the methylsiloxanes, which showed an annual average increase of about 30%. A downward trend (about 20% year⁻¹) was observed for the polybrominated diphenylethers (PBDEs 154 and 183), while PBDE 209 increased by 16%. Further measurements are required to determine if the substitution of PBDEs by chlorinated paraffins or organophosphorus compounds have resulted in increased concentrations of the latter in sludge.     

Nutzenergiebedarf für das Heizen und Kühlen einer Gebäudezone – Bilanzierung nach DIN V18599 Teil 2

Determination of the energy demand for heating and cooling of building zones. Balance calculation method according to DIN V 18599‐2. The balance calculation method of German standard DIN V18599 is using the well known and proven monthly balance calculation methods for the evaluation of the energy use for space heating. The method enables – supplemented with the energy demand for cooling, air‐conditioning and lighting – a consistently energy evaluation of a building. The method uses an integrative approach and takes the interaction of all participating crafts into consideration. Because of this integrative approach, the following boundary conditions are included in the balance calculation method: –·summer period (variable), –·variable heating period, –·division in periods of usage / no usage, –·cooling demand, –·air conditioning of supply air, –·lighting, –·variable solar protection devices, –·usage‐dependent internal sources, room conditions and air change rates. This method is consistent with the EU‐directive on the “Energy Performance Of Buildings” (EPBD) and complies the requirements of future regulations.     

Biological reactor resistance to inhibition

The phenomenon of complete substrate conversion within biological reactors in the presence of toxic compounds, called the Reactor Resistance to Inhibition (RRI), has been investigated. It was theoretically demonstrated that the RRI value, which means the highest concentration of inhibitor by which complete substrate conversion is possible, depends on liquid detention time. The excess detention time over that required for complete conversion, imply the existence of a “reserve” reaction potential. The value of this “reserve” can be reduced by inhibitor action with no influence on the observed substrate conversion rate. The influence of detention time on biological denitrification in Packed Bed Reactors in the presence of chromium Cr⁶⁺ was investigated. The RRI value for 1 h detention time was 1.5 mg l⁻¹ Cr⁶⁺. For 3 h detention time the RRI value was 22 mg l⁻¹ Cr⁶⁺. The relationship between the RRI value and detention time was linear.     

Treatment of raw domestic sewage in an UASB reactor

The treatment of raw domestic sewage at ambient temperatures in an upflow anaerobic sludge blanket (UASB) reactor with a volume of 120 l. and a height of 1.92 m was studied. The sewage had an average BOD₅ of 357 mg l⁻¹ and COD of 627 mg l⁻¹. Approximately 75% of the organic materials were in the suspended fraction. The sewage temperature ranged from 18 to 28°C during the experimental period. The reactor operated continuously for 9 months and assessed self-inoculation and raw domestic sewage purification. The unit was started without inoculum and ran during the entire experimental period with a hydraulic retention time of 4 h. During the experiment, a sludge bed build-up was observed. At the end of the experimental period, the predominance of spherical granular particles up to 6–8 mm in diameter was evident.

After a 4-month operation, it was observed that the inoculation/acclimatization steps had been concluded. Removal efficiencies of BOD₅ = 78%, COD = 74% and TSS = 72% were obtained. A typical gas production factor of 80 l kg⁻¹ COD added was observed and the CH₄ content of the biogas was 69%.     

Characteristic of resistance to compounds of chlorine of water microorganisms according to cultural-morphological indices

The paper has investigated cultural-morphological features of four bacterial isolates separated from drinking tap water and the same water sampled at different stages of its add-on treatment at water treatment facilities of the enterprise of special beverages. It has been found that one bacterial culture appeared the most insensitive to chlorine; its resistance to NaOCl at concentrations 1.4; 3; 5 and 7 mg/dm³ varies within the range 1–98%, while as the other three isolators demonstrated low resilience (0–16%). A parallel was drawn between morphological types of isolated bacterial isolates, their capacity to form a pellicle in the liquid-air interface and resistance to chlorine. A conclusion was made that resistance to rather high concentrations of sodium hypochlorite may be explained by a hypothesis about the connection of resistance and hormesis.     

Contaminant fluxes from sediment due to tubificid oligochaete bioturbation

The release of the hydrophobic organic compounds pyrene, dibenzofuran and phenanthrene from bioturbated freshwater sediments was studied in laboratory microcosms. Initial Tubificid oligochaete densities of 0, 6700 and 2.67 × 10⁴ individuals · m⁻² were employed. Under oxygen saturated conditions, the difference between the contaminant fluxes from the high-density bioturbated microcosms and controls remained essentially constant at 37 and 70 ng · cm²⁻² · d⁻¹ for pyrene and phenanthrene, respectively, corresponding to effective mass transfer coefficients of 0.16 and 0.37 cm/y. Under hypoxic conditions, worm defecation on the sediment surface increased and led to significantly increased fluxes to a maximum of 380, 490 and 940 ng · cm⁻² · d⁻¹, for pyrene, phenanthrene and dibenzofuran, respectively. Average bioturbation fluxes in the high-density microcosms of 246, 258 and 310 ng · cm⁻² · d⁻¹ for the respective compounds corresponded to effective mass transfer coefficients of 1.7, 3.2, and 7.5 cm/yr. Initial release rates from medium-density microcosms (25% of high density) were typically half the release rate of the high-density microcosms, indicating greater organism activity per individual at the lower density. The increased flux with the more soluble compounds likely reflects more rapid release at the sediment surface and the increased importance of porewater pumping over sediment particle reworking for migration of these compounds.     

Evaluation of chemicals to control the generation of malodorous hydrogen sulfide in waste water

The effect of hydrogen peroxide, sodium/calcium hypochlorite and ferrous/ferric salts on hydrogen sulfide dissolved in waste water were investigated to establish an effective odour control system for Kuwait Sewage Networks. The waste water samples were collected from the inlet structure of main pumping station with pressure pipelines and analyzed for dissolved sulfide and pH before and after addition of chemicals individually and in combination under controlled laboratory conditions. The waste water contained dissolved sulfide in the range of 18 to 25 mg/l and pH ranged between 7.2 and 7.8. Various concentrations of above mentioned chemicals were tried to determine the accurate chemical requirement for oxidation or precipitation of dissolved sulfide in waste water. The reaction temperature was maintained at 35°C (±2°C), the normal temperature of waste water in Kuwait during summer. To oxidize 1 g of sulfide 1.25, 2.0 and 1.8 g hydrogen peroxide, sodium hypochlorite and calcium hypochlorite were required respectively. To remove 1 g of sulfide by precipitation with ferrous sulfate and ferric salt solution, 8 g and 4 g ferrous and ferric salt were required respectively under laboratory investigations. A combination of sodium hydroxide and sodium hypochlorite was also studied to control malodorous hydrogen sulfide in waste water. The addition of sodium hydroxide with sodium hypochlorite in waste water reduced the demand of hypochlorite 50%. This procedure was found to be cost effective and best suited for the warm climate of Kuwait and was implemented in the field at a screw conveyor type lifting station with gravity sewer pipelines. When sodium hypochlorite was injected without shock loadings of sodium hydroxide 46% reduction of dissolved sulfides was recorded and it was increased to 57% with shock loadings of sodium hydroxide, though the quantity of sodium hypochlorite was reduced to half than the former case. Similarly, 45 and 70% reduction in the emission of gaseous hydrogen sulfide was recorded with NaOCl injection without and with NaOH shock loading respectively. The cost comparison of all the chemicals when applied in field is also presented.     

Lead concentration profiles in lead-210 dated Lake Ontario sediment cores

Lead concentrations were measured in sediment cores from four sites distributed among the three major sedimentary basins — Niagara, Mississauga and Rochester — of Lake Ontario for which sedimentation rates had been previously determined by ²¹⁰Pb dating.Around 90% of the total lead present in fine-grained surface sediments was removed by CH₃CO₂H/NH₂OH · HCl leaching, concentrations ranging from 137 μg/g in surface sections to a constant background of 12–13 μg/g at unpolluted depths. Lead-210 dating indicated that increases in lead concentrations commenced ca. 1850–1875 with 5, 10, 35 and 50% of the total “excess” lead inventory in the sediment column being assigned to the pre-1900 period and successive 25-year intervals during the 20th Century, respectively. Anthropogenic inputs of lead from such sources as the combustion of leaded gasoline and coal are responsible for these increases.About 10 μg/g lead remained in the sediment residue after leaching. The total natural lead flux to the sediments ranged from 0.4–1.3 μg/cm²/yr while “excess” lead of anthropogenic origin varied from 1.2–6.7 μg/cm²/yr and totalled 0.5–1.5 g/m² at the four sites.Various potential modes of introduction of anthropogenic lead and of ²¹⁰Pb to the lake are considered in conjunction with the ratio of Pb/²¹⁰Pb fluxes to the sediment.