Oxygen Transfer and Industrial Wastewater Treatment Efficiency of a Vertically Moving Biofilm System

A vertically moving biofilm system (VMBS) was developed to treat wastewater. In this system, the biofilm grows on a biofilm module consisting of plastic media that is vertically and repeatedly moved up into the air and down into the water. The objectives of this study were to investigate the oxygen transfer efficiency and industrial wastewater treatment performance of the VMBS. The oxygen transfer coefficient (K _L a) depended on the movement frequency (n) of the biofilm module and was proportional to n ^1.67. K _L a values measured were within the range of 0.0001 to 0.0027 s^-1. The VMBS exhibited good carbonaceous removal when treating industrial wastewater produced in a factory manufacturing synthetic fibres. Removal efficiency of filtered chemical oxygen demand (COD) and biological oxygen demand (BOD₅) was up to 93.2 and 97.9%, respectively. The volumetric removal rates of filtered COD and BOD₅ reached 1320 g COD m^-3 day^-1 and 700 g BOD₅ m^-3 day^-1. The areal organic removal rates, based on the surface area of the biofilm substrata, were 16 g BOD₅ m^-2 day^-1 and 39 g COD m^-2 day^-1. No clogging occurred during the experiment. The mean areal biofilm mass increased with increasing the mean areal BOD₅ removal rate. The new biofilm process has such advantages as high carbonaceous oxidation, energy saving, simpleconstruction and easy operation for industrial wastewater treatment.     

A Novel High Capacity Biofilm Reactor System for Treatment of Domestic Sewage

A lab-scale novel biofilm reactor system, Ultra-Compact Biofilm Reactor (UCBR), was studied to investigate its performance and operational characteristics for domestic sewage treatment. The reactor was operated at four different hydraulic retention times, namely, 90, 60, 30 and 15 min. The operating ranges of volumetric loading rates in terms of COD, BOD₅, NH⁺ ₄-N and TKN were 5.6-62.1 kg COD/m³ d, 2.6-32.5 BOD₅/m³ d, 0.6-3.2 kg NH⁺ ₄-N/m³ d and 0.82-6.2 kg TKN/m³ d, respectively. The COD, BOD₅ and NH⁺ ₄-N removal efficiencies at 90-min hydraulic retention time (HRT) and 60-min HRT could exceed 80%, 90% and 99%, respectively. The corresponding maximum biomass concentrations were 12.0 g/L and 15.0 g/L at 90-min HRT and 60-min HRT, respectively. At 30-min HRT, the biomass concentration increased to a maximum of 24.0 g/L. However, COD and BOD₅ removal efficiencies decreased to 75% and 80%, respectively, while the NH⁺ ₄-N nitrification efficiency decreased to only 25% to 30%. These observations suggested that high biomass concentration alone was not sufficient to provide a high removal capacity in a UCBR. Further reduction in HRT to 15 min led to an excessive biomass decline from 22.5 g/L to 4.0 g/L. On the whole, the UCBR was able to sustain COD removal and NH⁺ ₄-N conversion of up to 5.96-18.70 kg COD/m³ d and 0.73-1.00 kg NH⁺ ₄-N/m³ d, respectively.     

Impact of sanitary landfill on groundwater quality

This paper presents the results of monitoring the shallow groundwater quality around two municipal landfill sites in the Eastern Province of Saudi Arabia. Boreholes were installed at Dhahran and Juaymah sites upstream and downstream of the landfill. Twenty water samples were collected from each borehole and analyzed for various parameters mainly for BOD, COD, TOC, NH₃-N, TKN, sulphate, chloride, hardness and metals. The result of the analysis of water samples from Dhahran boreholes shows an increase in the concentration of pollutants in downstream groundwater over that observed in upstream boreholes. The average concentration of BOD₅, COD and TOC in the samples obtained from the downstream borehole was found to be 6.5, 23.5, and 34.3 mg L^?1, respectively. On the other hand, the mean concentration of the same parameters in upstream monitoring wells was found to be less than 2.4, 11.5, and 10.0 mg L^?1, respectively. The ammonia-N and organic-N in the downstream wells were 0.37 and 0.29 mg L^?1, respectively, whereas, in upstream wells they were 0.11 and 0.15 mg L^?1, respectively. At Juaymah, the average concentration of BOD and TOC in groundwater samples obtained from upstream boreholes were less than 3.0 and 7.2 mg L^?1, respectively, while the concentration of the same parameters in downstream well samples were above 5.0 and 35.0 mg L^?1, respectively. A similar trend of increment of ammonia-N, organic-N, phosphate, sulfate and metals in downstream samples was observed. Since the water from these shallow aquifers at both places is not being used for human consumptions or for any other commercial purpose, therefore, the minor increase in pollutants concentration at downstream level is not of a great concern.     

Microfauna Community as an Indicator of Effluent Quality and Operational Parameters in an Activated Sludge System for Treating Piggery Wastewater

In order to study the potential use of microfauna as an indicator of effluent quality and operational parameters in an activated sludge system for treating piggery wastewater, an experimental sequencing batch reactor was set up and evaluated by biological and physical–chemical analyses for 12 months. Results show that microfauna (and specifically ciliate protozoa) are a good parameter for assessing effluent quality in terms of both chemical oxygen demand (COD) and ammonia and for assessing the organic and nitrogen load of the system. Specifically, the abundance of ciliates decreases from 20,000 individuals·mL^?1 to ca. 2,500 individuals·mL^?1 and from ca. 10,000 individuals mL^?1 to ca. 200 individuals mL^?1 when effluent concentration is between 550 and 750 mg L^?1 and above 100 mg L^?1 to the COD and ammonia concentrations, respectively. Furthermore, microfauna abundance is reduced from ca. 18,000 individuals mL^?1 (organic load between 0.1 and 0.2 mg COD mg total suspended solids (TSS)^?1 day^?1) to ca. 500 individuals mL^?1 (organic load between 0.3 and 04 mg COD mg TSS^?1 day^?1). Microfauna abundance also decreases as nitrogen loading increases. Nitrogen loading in the range of 5–60 mg NH₄–N g TSS^?1 day^?1 does not have any significant effect on microfauna abundance. However, ammonia loading from 60 to 120 mg NH₄–N g TSS^?1 day^?1 reduces microfauna abundance ca. 6-fold. Ciliate protozoa were the largest microfauna group during the whole period of study, representing ca. 75% of the total microfauna abundance. The largest group in the ciliate community was that of the free-swimming ciliates. This was followed by the group of attached and crawling ciliates. Specifically, the dominant ciliate species during the whole study period were Uronema nigricans, Vorticella microstoma-complex, Epistylis coronata, and Acineria uncinata.     

Characteristics of Nitrous Oxide (N2O) Emissions from Intermittently-Aerated Sequencing Batch Reactors Treating the Separated Liquid Fraction of Anaerobically Digested Pig Manure

In this study, the N₂O emission from an intermittently aerated sequencing batch reactor (IASBR-1) treating the separated liquid fraction of anaerobically digested pig manure (SLAP) was investigated. The wastewater had chemical oxygen demand (COD) concentrations of 11,540?±?860?mg?l^?1, 5-day biochemical oxygen demand (BOD₅) concentrations of 2,900?±?200?mg?l^?1and total nitrogen concentrations of 4,041?±?59?mg?l^?1, with low COD:N ratios (2.9, on average) and BOD₅:N ratios (0.72, on average). Synthetic wastewater, simulating the SLAP with similar COD and nitrogen concentrations but with higher BOD₅ concentrations of up to 11,500?±?100?mg?l^?1, was treated in another identical reactor (IASBR-2) to compare the effects of carbon source on nutrient removals and N₂O emissions. In steady-state, soluble N₂O accumulated in the non-aeration periods, with the highest N₂O concentrations measured at the end of the non-aeration periods. There was a significant reduction in N₂O concentrations during the aeration periods with reductions occurring immediately on commencement of aeration. The mean N₂O emissions in an operational cycle were 253.6 and 205.3?mg for IASBR-1 and IASBR-2, respectively. During the non-aeration periods, only 8.3% and 8.4% of total N₂O emissions occurred in IASBR-1 and IASBR-2, respectively; while during the aeration periods, 91.7% and 91.6% of N₂O emissions took place in IASBR-1 and IASBR-2, respectively. The mean specific N₂O generation rates were 0.010 and 0.005?mg (g VSS·min)^?1 in the aeration periods, 0.024 and 0.021?mg (g VSS·min)^?1 in the non-aeration periods for IASBR-1 and IABSR-2, respectively. Mean nitrogen removal via N₂O emissions was 15.6% and 10.1% for IASBR-1 and IASBR-2, respectively. The IASBR-1 with low influent BOD₅ concentrations emitted and generated more N₂O.     

Concentrations and Exports of Fecal Indicator Bacteria in Watersheds with Varying Densities of Onsite Wastewater Systems

The research goal was to determine if onsite wastewater system (OWS) density had an influence on the concentrations and watershed exports of Escherichia coli and enterococci in urbanizing watersheds. Eight watersheds with OWS densities ranging from <?0.1 to 1.88 systems ha^?1 plus a watershed served by sewer (Sewer) and a mostly forested, natural watershed (Natural) in the Piedmont of North Carolina served as the study locations. Stream samples were collected approximately monthly during baseflow conditions between January 2015 and December 2016 (n?=?21). Median concentrations of E. coli (2014 most probable number (MPN) 100 mL^?1) and enterococci (168 MPN 100 mL^?1) were elevated in streams draining watersheds with a high density of OWS (>?0.77 system ha^?1) relative to watersheds with a low (<?0.77 system ha^?1) density (E. coli: 204 MPN 100 mL^?1 and enterococci: 88 MPN 100 mL^?1) and control watersheds (Natural: E. coli: 355 MPN 100 mL^?1 and enterococci: 62 MPN 100 mL^?1; Sewer: 177 MPN 100 mL^?1 and 130 MPN 100 mL^?1). Samples collected from watersheds with a high density of OWS had E. coli and enterococci concentrations that exceeded recommended thresholds 88 and 57% of times sampled, respectively. Results show that stream E. coli and enterococci concentrations and exports are influenced by the density of OWS in urbanizing watersheds. Cost share programs to help finance OWS repairs and maintenance are suggested to help improve water quality in watersheds with OWS.     

A comparative study of permeable layer materials and aeration regime on efficiency of multi-soil-layering system for domestic wastewater treatment in Thailand

Abstract

Multi-soil-layering (MSL) system was designed for purifying domestic wastewater and for treating polluted river water. MSL system is typically comprised of layers of soil mixture blocks alternating with permeable layers. The permeable layer has roles of preventing clogging and to increasing the efficiency of infiltration of wastewater through the soil mixture blocks. In this study, the comparative efficiency of five MSL systems as a function of five permeable layer materials (zeolite, zeolitized perlite, perlite, gravel, and charcoal) was investigated. The MSL systems were constructed in 15 × 50 × 100 cm boxes where the soil mixture blocks contained sandy clay soil, kenaf + corncob, and iron scraps at a ratio of 6 : 1 : 1 by weight, respectively, and filled up in alternation with the permeable layer. The results indicated that all the MSL systems at loading rates of 96–346 L m^?2 d^?1 under nonaerated conditions were able to reduce the levels of COD (342–1,231 mg L^?1), BOD₅ (201–802 mg L^?1), and soluble reactive phosphorus (SRP) (3.5–10.1 mg P L^?1) at percentages of 79.0–98.1, 80.0–99.6, and 97.1–100%, respectively. The zeolite and the charcoal-based MSL systems under a 96–346 L m^?2 d^?1 loading rate effectively reduced the level of TN (41.4–65.5 mg N L^?1) at percentages of 79.0–92.1 and 30.7–88.9%, respectively. In terms of prevention of clogging, the charcoal-based MSL system was the most effective, followed by the gravel and zeolite-based MSL. The apparent efficiency of pollutant removal, for zeolitized perlite, perlite, and gravel-based MSL systems was low. With an on-off aeration operation, the efficiency of the MSL systems in the reduction of the levels of COD, BOD₅ , and SRP (hereafter reference to as “removal”) was significantly enhanced. Overall, the zeolite-based MSL system seemed to be more effective than the other MSL systems. However, if optimum aeration could be obtained, the removal efficiency of charcoal-based MSL system might be improved. Aeration at a rate of 64,000 L m^?3 d^?1 for 1 week alternating with 2 weeks of nonaeration enhanced the removal of COD, BOD₅ , and SRP but not that of TN.     

Bionutrient Removal with a Sequencing Batch Reactor

Removal of nitrogen and phosphorus from a domestic wastewater using a sequencing batch reactor (SBR) was evaluated at solid retention times (SRTs) of 9.3, 13.8, and 18.3 days respectively. Oxygen uptake rates (OURs) and sludge settling characteristics were determined at each SRT investigated. COD removal, nitrification, denitrification, and phosphorus removal were accomplished by using the following operating cycle: 15-min unmixed fill; 2-hr mixed anaerobic period; 3-hr mixed aerobic period; 3-hr mixed anoxic period; 0.5-hr reaeration period; 1-hr settling period; 1-hr decant period; and a 1.5-hr idle period. Advanced wastewater treatment (AWT) standards of 5/5/3/1 mg L^-1 for biochemical oxygen demand (BOD₅), suspended solids (SS), total nitrogen (TN), and total phosphorus (TP) could not be achieved with the bench-scale SBR.     

Efficiency of Bark, Activated Charcoal, Foam and Sand Filters in Reducing Pollutants from Greywater

Greywater is a potential resource of water that can be improved to meet the quality needed for irrigation. This study evaluated the performance of bark, activated charcoal, polyurethane foam and sand filters in removing biochemical oxygen demand (BOD₅), surfactants, phosphorus, nitrogen and microbial indicators from greywater during start-up and steady state. In column experiments, 0.6?m high filters (diameter 20?cm) were fed for 113?days with artificial greywater at a hydraulic loading rate of 0.032?m³?m^?2?day^?1 and an organic loading rate of 0.014?kg BOD₅ m^?2?day^?1. Bark and activated charcoal efficiently reduced the concentrations of organics (BOD₅), surfactants (methylene blue active substances??MBAS), total phosphorus (Tot-P) and total thermotolerant coliform numbers, while sand and foam were less efficient. Bark, activated charcoal, foam and sand reduced influent BOD₅ by 98, 97, 37 and 75?%; MBAS by >99, >99, 73 and 96?%; Tot-P by 97, 91, 36 and 78?%; and total nitrogen by 19, 98, 13 and 5?%, respectively. BOD₅ and MBAS were efficiently reduced directly from start-up by bark and activated charcoal, while foam needed 30?days to achieve about 50?% reduction in BOD₅. Bark was the most efficient filter in reducing thermotolerant faecal coliforms (2.4 log₁₀), while foam achieved the lowest reduction (0.5 log₁₀). Overall, bark and activated charcoal filters appeared to be the most suitable filters for improving greywater quality to reach irrigation quality in terms of organic matter reduction. Performance of these filters under higher and fluctuating loadings and the long-term sustainability of the filter materials need further investigation.     

爵床提取物的抑菌杀虫活性研究

爵床(Justicia procumbens var.procumbens L.)是一种传统中药。为探明爵床提取物的抑菌杀虫活性,采用冷浸和超声波提取相结合的方法,分别获得了爵床甲醇、氯仿、丙酮、乙酸乙酯和正己烷等溶剂提取物;并应用抑菌圈法研究了5种提取物对柑橘炭疽病菌(Colletotrichum gloeosprioides)、芦笋茎枯病菌(Phomopsisasparagi)、稻瘟病菌(Pyricularia grisea)、棉花红腐病菌(Fusarium graminearum)和草莓灰霉病菌(Botrytiscinerea)等5种植物病原真菌的抑制效果,测定了甲醇提取物对柑橘炭疽病、芦笋茎枯病、草莓灰霉病和柑橘溃疡病(Xanthomonas campestris)等4种植物病菌及白蚊伊蚊(Aedes albopictus)、家蝇(Musca domestica)和菜青虫(Pieris rapae)等3种害虫的毒力。结果表明,不同极性溶剂提取物8 mg.mL 1对5种植物病原真菌均有一定的抑制作用,其中甲醇提取物对柑橘炭疽病菌、芦笋茎枯病菌、草莓灰霉病菌的抑制率均达50%以上。爵床甲醇提取物具有较强的抑菌杀虫活性,对柑橘炭疽病菌、芦笋茎枯病菌和草莓灰霉病菌菌丝生长的抑制中浓度(EC50)分别为5.94 mg.mL 1、4.61 mg.mL 1和5.27 mg.mL 1,EC90分别为63.69 mg.mL 1、58.01 mg.mL 1和54.57 mg.mL 1;0.25~1.00 mg.mL 1爵床甲醇提取物对柑橘溃疡病病菌显示强抑菌作用,0.125 mg.mL 1显示中度抑菌作用,最小抑制浓度(MIC)为0.062 5 mg.mL 1;爵床甲醇提取物对白蚊伊蚊、家蝇和菜青虫的致死中浓度(LC50)分别为0.195 8 mg.mL 1、0.351 4 mg.mL 1和0.287 7 mg.mL 1,LC95分别为0.988 4 mg.mL 1、3.053 2mg.mL 1和2.584 4 mg.mL 1。因此,爵床提取物作为生物农药,在农业生产中具有较好的应用前景。     

Operational Optimisation of Pilot Scale Biological Nutrient Removal at the Ciudad Real (Spain) Domestic Wastewater Treatment Plant

The aim of this work is optimising operating conditions for a possibleimplementation of a Biological Nutrient Removal (BNR) process in the Wastewater Treatment Plant (WWTP) of Ciudad Real (Spain). Several factors (hydraulic retention times, anaerobic nitrate concentration, sludge age and wastewater biodegradability) were tested using a pilot scale VIP (Virginia Initiative Plant) activated sludge process and domestic wastewater from the full scale plant. Hydraulic retention times used did not cause changes in N and P removal. P removal was adversely affected by anaerobic NO₃ ^- and improved with higher BOD₅/COD ratios in wastewater. Influence of sludge age was very low in P removal, but N removal was mainly affected by this factor. Final operating conditions were selected taking into account their effects over one of both nutrients. COD and SS removal were always successful. N removal was also easily reached and the main difficulty was P removal. P sludge content was very low (2.5–4%) approximately and was also affected by the same factors tested. The main factor to improve P removal was supposed to be the organic wastewater composition. Wastewater characteristics were modified by using different sources from the WWTP. Volatile fatty acids (VFA) addition to the wastewater by using supernatant of the anaerobic sludge digesters seemed to be the best practical solution for a future BNR implementation in the WWTP.     

Optimization of Petroleum Refinery Wastewater Treatment by Vertical Flow Constructed Wetlands Under Tropical Conditions: Plant Species Selection and Polishing by a Horizontal Flow Constructed Wetland

Typha latifolia-planted vertical subsurface flow constructed wetlands (VSSF CWs) can be used to treat petroleum refinery wastewater. This study evaluated if the removal efficiency of VSSF CWs can be improved by changing the plant species or coupling horizontal subsurface flow constructed wetlands (HSSF CWs) to the VSSF CW systems. The VSSF CWs had a removal efficiency of 76% for biological oxygen demand (BOD₅), 73% for chemical oxygen demand (COD), 70% for ammonium-N (NH₄⁺-N), 68% for nitrate-N (NO₃^?-N), 49% for phosphate (PO₄^3?-P), 68% for total suspended solids (TSS), and 89% for turbidity. The HSSF CWs planted with T. latifolia further reduced the contaminant load of the VSSF CW-treated effluent, giving an additional removal efficiency of 74, 65, 43, 65, 58, 50, and 75% for, respectively, BOD₅, COD, NH₄⁺-N, NO₃^?-N, PO₄^3?-P, TSS, and turbidity. The combined hybrid CW showed, therefore, an improved effluent quality with overall removal efficiencies of, respectively, 94% for BOD₅, 88% for COD, 84% for NH₄⁺-N, 89% for NO₃^?-N, 78% for PO₄^3?-P, 85% for TSS, and 97% for turbidity. T. latifolia strived well in the VSSF and HSSF CWs, which may have contributed to the high NH₄ ⁺-N, NO₃^?-N, and PO₄^3?-P removal efficiencies. T. latifolia-planted VSSF CWs showed a higher contaminant removal efficiency compared to the unplanted VSSF CW. T. latifolia is thus a suitable plant species for treatment of secondary refinery wastewater. Also a T. latifolia-planted hybrid CW is a viable alternative for the treatment of secondary refinery wastewater under the prevailing climatic conditions in Nigeria.     

湖南洞庭湖区农地畜禽粪便承载量估算及其风险评价

根据洞庭湖区畜禽养殖现状,采用排泄系数估算法测算了洞庭湖区畜禽粪便产生量,并对不同农地畜禽粪便承载量和畜禽粪便污染风险进行了评估.结果表明:2006年,洞庭湖区年产畜禽粪1 616.93万t,尿液1 248.30万t,BOD5 72.41万t,COD 79.33万t,NH3-N 7.48万t,农地畜禽粪便承载量平均为19.25 t·hm-2,风险预警值平均为0.47,仍未造成环境污染,畜禽养殖业还有较大发展空间.但个别地区的畜禽粪便已对农地造成污染,必须引起注意.     

A Study of Surface Water Quality in Macedonia,Greece: Speciation of Nitrogen and Phosphorus

A 2-yr (1997–1998) survey aiming at the establishment of national data bases concerning the quality of surface waters has been conducted in the major river systems of Macedonia, N. Greece. This paper presents the physicochemical parameters(pH, conductivity, total suspended solids, temperature and DO),the organic pollution parameters (BOD₅, COD) and the major N and P species (NO₃ ^-, NO₂ ^-,NH₄ ⁺,organic N, orthophosphates and total P) determined at 25 sampling sites located on main rivers, tributaries, streams andditches that drain the major rural, agricultural, urban and industrial areas of N. Greece. Use of multivariate statistics is also made to identify the principal factors which influencethe chemistry of the water in individual river systems.The eutrophication status of the examined systems was evaluatedby means of N/P ratios. Mean N/P ratios showed large variationsamong sampling sites ranging from potential N- to P-limitationconditions. N/P ratios at particular sampling sites showed also great temporal variability thus suggesting temporary states of N- or P- limitation. Most frequently, highest ratio values wereobserved during winter and early spring. Comparisons are made between data from this study region and literature on rivers elsewhere.     

Evaluation of On-site Wastewater Disposal Systems in Mississippi Coastal Areas

Groundwater and surface water contamination have been linked to inadequate or failing on-site residential wastewater treatment and disposal systems. The potential for groundwater contamination in coastal areas with shallow water tables is higher; subsequently the ability of soil, microorganisms, and vegetation to mitigate pollutants may be reduced. This study evaluated the performance of the four types of on-site wastewater treatment and disposal systems predominantly used on the Mississippi Gulf Coast. One type of system was deemed inappropriate for this region as none of the dozens of installations examined were functioning acceptably. Of the remaining three types, subsurface water samples were collected from representative sites using lysimeters and monitoring wells. Apart from general performance evaluation of these systems, seasonal changes translating into possible variation in disposal efficiencies and groundwater contamination were investigated. Statistical analysis of variations in organics (COD and BOD₅), nitrogen (TKN and NH ₄ ⁺ ?CN), and fecal coliform concentrations was used to identify probable deficiencies in systems tested and to recommend changes to governing standards.     

Oxygen Demand of Aircraft and Airfield Pavement Deicers and Alternative Freezing Point Depressants

Aircraft and pavement deicing formulations and other potential freezing point depressants were tested for biochemical oxygen demand (BOD) and chemical oxygen demand (COD). Propylene glycol-based aircraft deicers exhibited greater BOD₅ than ethylene glycol-based aircraft deicers, and ethylene glycol-based products had lower degradation rates than propylene glycol-based products. Sodium formate pavement deicers had lower COD than acetate-based pavement deicers. The BOD and COD results for acetate-based pavement deicers (PDMs) were consistently lower than those for aircraft deicers, but degradation rates were greater in the acetate-based PDM than in aircraft deicers. In a 40-day testing of aircraft and pavement deicers, BOD results at 20°C (standard) were consistently greater than the results from 5°C (low) tests. The degree of difference between standard and low temperature BOD results varied among tested products. Freshwater BOD test results were not substantially different from marine water tests at 20°C, but glycols degraded slower in marine water than in fresh water for low temperature tests. Acetate-based products had greater percentage degradation than glycols at both temperatures. An additive component of the sodium formate pavement deicer exhibited toxicity to the microorganisms, so BOD testing did not work properly for this formulation. BOD testing of alternative freezing point depressants worked well for some, there was little response for some, and for others there was a lag in response while microorganisms acclimated to the freezing point depressant as a food source. Where the traditional BOD₅ test performed adequately, values ranged from 251 to 1,580?g/kg. Where the modified test performed adequately, values of BOD₂₈ ranged from 242 to 1,540?g/kg.     

Evaluation of some Methods for Fish Canning Wastewater Treatment

A fish canning facility processes 1900–2000 tons of mackerel and sardine annually at arate of 10–15 tons per day for a total of 200 days yr^-1. This factory generates an average of 20 m³ of industrial wastewaters per day. The objective of our study, which was carried out on a bimonthly basisfrom December 1995 to November 1996, was to determine the overall pollutant load associated with this effluent in relation to the applicable Egyptian Standards and to propose methods for pollutant load reduction before discharging it to the local sewer. The methods were to benefit through the recovery of wasted organic load and transform it into an environmentally safe residue amenable for either immediate reuse or final disposal thereafter. Five chemical coagulation/flocculation treatments were tried using ferric chloride, alum, lime, ferric chloride and lime, and alum and lime. The best method involved the use of FeCl₃ and Ca(OH)₂ (0.4 g Fe L^-1 and 0.2 g Ca L^-1, respectively) which reduced the average influent BOD₅ from 989 to 204 mg L^-1, the COD from 1324 to 320 mg L^-1, TSS from 4485 to 206 mg L^-1, total protein content from 812 to 66 mg L^-1 and oil and grease from 320 to 66 mg L^-1. The separated dried precipitate averaged 50 g L^-1 which was found to contain 40% by weight recovered protein and 20% recovered fat. The solid was ideal for on-site reprocessing as animal feed. As well, the final effluent, if not discharged to the area sewer, was safe for controlled use in some irrigation applications or forestry projects at the desert area surrounding the factory.     

Preparation of Modified Magnetic Cobalt Nanoparticles as a New Magnetic Sorbent for the Preconcentration and Determination of Trace Amounts of Lead Ions in Environmental Water and Soil (Air-Dust) Samples

In this study, cobalt magnetic nanoparticles (MNPs) were synthesized and then modified by sodium dodecyl sulfate (SDS) and 2-(5-bromo-2-pyridylazo)-5-diethyl aminophenol ligand (5-Br-PADAP), through a chemical precipitation method. Characterization of the prepared MNP adsorbents was performed by Fourier transform infrared and transmission electron microscopy. Cobalt nanoparticles (NPs) surface modified with SDS and 5-Br-PADAP was evaluated as a nanoparticulate solid-phase extraction (SPE) absorbent for lead ions Pb(II) from water and standard samples, prior to its flame atomic absorption spectrometry determination. Effects of pH, amount of sorbent, desorption solvent, adsorption time, desorption time, and interfering ion concentration on extraction efficiency were investigated. Under optimal conditions, the calibration curve was linear in the range of 1.0–500 ng mL^?1of Pb(II) with R² = 0.998. Detection limit was 1.6 ng mL^?1 in the original solution (3S_b/m), and the relative standard deviation for replicate determination of 0.5 μg mL^?1 Pb(II) was ±2.7%.     

Biochemical Oxygen Demand Relationships in Typical Agricultural Effluents

Understanding the variables controlling biochemical oxygen demand (BOD) of effluents from agricultural systems is essential for predicting and managing the water quality risks associated with agricultural production. In this study, short- and long-term oxygen demand behaviors of waters from primarily agricultural sources and their relationships with other parameters were evaluated. A total of 46 water samples were generated from diverse organic sources commonly associated with agricultural activities and analyzed for BOD and other various water quality parameters. Short-term BOD (BOD₂ and BOD₅) were significantly correlated with total organic carbon (TOC), particulate organic carbon (POC), and dissolved organic carbon (DOC) (R ²?=?0.62–0.77, p?<?0.001), likewise to total nitrogen, total Kjeldahl nitrogen, and nitrite–nitrogen (NO₂–N) (R ²?=?0.40–0.55, p?<?0.001). Long-term BOD (BOD₆₀) was generally poorly correlated with these C and N fractions. Phosphate (PO₄–P) exhibited a positive and linear relationship with both short- and long-term BOD, whereas chloride (Cl) tended to inhibit oxygen demand. Multivariate combinations of each of TOC, POC, and DOC with NO₂–N, and Cl or PO₄–P improved the predictions of both short- and long-term BOD. The ultimate BOD (BOD_u) derived from the first-order kinetics was highly correlated with BOD₆₀ (R ²?=?0.81, p?<?0.001) whereas BOD₆₀ was correlated with BOD₅ (R ²?=?0.60, p?<?0.001). Overall the results indicated that C and N forms along with PO₄–P and Cl were the dominant factors controlling the oxygen demand behaviors of agricultural effluents.     

Characterization of cultivable methanotrophs from paddy soils and rice roots

Abstract

Characterization of methanotrophs isolated from paddy soils and rice (Oryza sativa) roots was investigated in the present study. The number of methanotrophs in root homogenates of the rice cultivar Mutsuhomare was 4.9 × 10⁷ most-probable-number (MPN) g^?1 dry roots, in Yumeakari it was 2.0 × 10⁸ MPN g^?1 dry roots and in Kirara it was 4.6 × 10⁷ MPN g^?1 dry roots. Although bacterial cells were observed infrequently on the surface and in the interiors of roots before incubation, a large number of colonies, measuring 0.5–5 mm in diameter, were observed on the sterilized roots after incubation on nitrate mineral agar plates under methane in air. In particular, a large number of colonies were observed at the emergence sites of lateral roots and root hairs. Strains MD5-1 and M1 were isolated from the roots of Mutsuhomare and strain R62 was isolated from the root homogenate of Yumeakari. All isolates were catalase-positive and oxidase-positive, Gram-negative, straight-rod-shaped and curved-rod-shaped bacteria, and formed exospores. The isolates were able to fix nitrogen and grew in the absence of copper. In addition, all were found to be positive for naphthalene-oxidizing activities (corresponding to soluble methane mono-oxygenase activities). Strains MD5-1, M1 and R62 were closely related to Methylosinus sporium. Methanotrophic strains W3-6, SD3-5 and 2-19, isolated previously from paddy field soils, were classified into Methylosinus (W3-6) and Methylocystis (SD3-5 and 2-19) type II methanotrophs. Isolates from the rice roots (MD5-1, R62 and M1) grew logarithmically when casamino acid was used as the nitrogen source; however, the growth of these strains was reduced on the nitrate medium. These strains preferred amino acids over inorganic nitrogen as a nitrogen source for growth.