Slaughterhouse wastewater treatment: evaluation of a new three-phase separation system in a UASB reactor.

The anaerobic treatment of the wastewater from the meat processing industry was studied using a 7.2 1 UASB reactor. The reactor was equipped with an unconventional configuration of the three-phase separation system. The effluent was characterized in terms of pH (6.3-6.6), chemical oxygen demand (COD) (2,000-6,000 mg l(-1)), biochemical oxygen demand BOD5 (1,300-2,300 mg 1(-1)), fats (40-600 mg l(-1)) and total suspended solids (TSS) (850-6,300 mg l(-1)) The reactor operated continuously throughout 80 days with hydraulic retention time of 14, 18 and 22 h. The wastewater from Rezende Industrial was collected after it had gone through pretreatment (screening, flotation and equalization). COD, BOD and TSS reductions and the biogas production rate were the parameters considered in analyzing the efficiency of the process. The average production of biogas was 111 day(-1) (STP) for the three experimental runs. COD removal varied from 77% to 91% while BOD removal was 95%. The removal of total suspended solids varied from 81% to 86%. This fact supports optimal efficiency of the proposed three-phase separation system as well as the possibility of applying it to the treatment of industrial effluents.     

Behavior of lipids in biological wastewater treatment processes

Lipids (characterized as oils, greases, fats and long-chain fatty acids) are important organic components of wastewater. Their amount, for example, in municipal wastewater is approximately 30–40% of the total chemical oxygen demand. The concern over the behavior of lipids in biological treatment systems has led to many studies, which have evaluated their removal, but still the exact behavior of lipids in these processes is not well understood. In this review, we discuss the current knowledge of how lipids/fatty acids affect both aerobic and anaerobic processes and specific methods that have been used in an attempt to enhance their removal from wastewater. Overall, the literature shows that lipids/fatty acids are readily removed by biological treatment methods, inhibitory to microbial growth as well as the cause of foaming, growth of filamentous bacteria and floc flotation.     

Organic and nitrogen removal in a two-stage rotating biological contactor treating municipal wastewater

A laboratory scale rotating biological contactor (RBC) predenitrification system incorporating anoxic and aerobic units was evaluated for the treatment of settled high-strength municipal wastewater. The system was operated under four recycle ratios (1, 2, 3 and 4) and loading rates of 38-182 gCOD/m(2)d and 0.22-14 gOxid-N/m(2)d on the anoxic unit and 3.4-18 gCOD/m(2)d and 0.24-1.8 gNH(4)-N/m(2)d on the aerobic. The average removal efficiency in terms of chemical oxygen demand (COD), biochemical oxygen demand (BOD(5)), total suspended solids (TSS) and total nitrogen (Total-N) was 82%, 86%, 63% and 54%; settling of the RBC effluent increased COD and TSS removal to 94% and 97%. An increase in hydraulic loading resulting from higher recirculation, had limited negative effect on organic removal but improved nitrogen removal, and in terms of Total-N removal efficiency increased up to a ratio of 3 and then decreased.     

Calculation of the release of total organic matter and total mineral using the hydrodynamic equations applied to palm oil mill effluent treatment by cascaded anaerobic ponds

Anaerobic treatment processes to remove organic matter from palm oil mill effluent (POME) have been used widely in Malaysia. Still the amounts of total organic and total mineral released from POME that may cause degradation of the receiving environment need to be verified. This paper proposes the use of the hydrodynamic equations to estimate performance of the cascaded anaerobic ponds (CAP) and to calculate amounts of total organic matter and total mineral released from POME. The CAP efficiencies to remove biochemical oxygen demands, chemical oxygen demands, total solids and volatile solids (VS) as high as 94.5, 93.6, 96.3 and 98.2 %, respectively, are estimated. The amounts of total organic matter and total mineral as high as 538 kg VS/day and 895 kg FS/day, respectively, released from POME to the receiving water are calculated. The implication of the proposed hydrodynamic equations contributes to more versatile environmental assessment techniques, sometimes replacing laboratory analysis.     

Treatment of wastewater from abattoirs before land application--a review

Pre-treatments are screening, catch basins, flotation, equalization, and settlers for recovering proteins and fats from abattoir wastewater. With chemical addition, dissolved air flotation (DAF) units can achieve chemical oxygen demand (COD) reductions ranging from 32% to 90% and are capable of removing large amounts of nutrients. Aerobic trickling towers reduced soluble COD by additional 27% but did not reduced total COD. Chemical-DAF reduced 67% of total COD and soluble COD. About 40-60% of the solids or approximately 25-35% of the biological oxygen demand (BOD) load can be separated by pre-treatment screening and sedimentation. Anaerobic systems are lagoon, anaerobic contact (AC), up-flow anaerobic sludge blanket (UASB), anaerobic sequence batch reactor (ASBR), and anaerobic filter (AF) processes. Abattoir wastewater is well suited to anaerobic treatment because it is high in organic compounds. Typical reductions of up to 97% BOD, 95% SS and 96% COD are reported. UASB's average COD removal efficiencies are of 80-85%. UASB seems to be a suitable process for the treatment of abattoir wastewater, due to its ability to maintain a sufficient amount of viable sludge. Wastewater in abattoirs can be reduced by treatment of immersion chiller effluent by membrane filtration which can produce recyclable water. Total organic C can be reduced below 100mg/L, and bacteria can not pass through the membrane pores. The abattoir waste minimization options are also discussed.     

Electrochemical oxidation for the treatment of textile industry wastewater

This study elucidates the reduction of organics from textile effluents through electrochemical oxidation technique. Effect of pH and current intensity were investigated in this system. It was found that degradation was maximum at the current intensity of 0.6 A and at a pH of 1.3. Under the same experimental conditions the removal of chemical oxygen demand (COD), total solids, total dissolved solids and total organic carbon were found to be approximately 68%, 49.2%, 50.7% and 96.8%, respectively. Effect of current intensity on color removal was also investigated as a function of electrolysis time (30-210 minutes) and it showed that maximum removal efficiency (96%) was reached within 60 minutes at 0.6 A. While studying the effect of pH on COD removal, it was observed that a decrease in pH to an optimum of 1.3 showed maximum COD reduction of 68%. These results suggest an important role of these parameters in electrochemical process for removing organic pollutants.     

Start-up alternatives and performance of an UASB pilot plant treating diluted municipal wastewater at low temperature

Different start-up procedures of an upflow anaerobic sludge bed (UASB) digester were carried out. Start-up without inoculum (experiment A) was delayed for about 120 day. The digester reached 75-85% total suspended solids (TSS) removal, 54-58% total chemical oxygen demand (TCOD) removal and 63-73% biological oxygen demand (BOD5) removal at influent concentrations of 240-340 mg TCODil-1, temperatures of 13.5-15 degrees C and hydraulic retention times (HRT) of 10-11 h. Digested sludge was used as inoculum in experiment B. After the start-up period of 75 days, digester efficiencies were 58%, 41% and 54% for TSS, TCOD and BOD5 removal, respectively, working at 169 mg TCODil-1, temperature of 14 degrees C and HRT of 11 h. The sludge bed developed and stabilised quickly when using a hydraulically adapted inoculum (experiment C), but TCOD and BOD5 removals remained low and volatile fatty acids (VFA) accumulated in the effluent.     

Use of native aquatic macrophytes in the reduction of organic matter from dairy effluents

Considering the diversity and the unexplored potential of regional aquatic flora, this study aimed to identify and analyze the potential of native aquatic macrophytes to reduce the organic matter of dairy wastewater (DW) using experimental constructed wetlands. The dairy wastewater (DW) had an average chemical oxygen demand (COD) of 7414.63 mg/L and then was diluted to 3133.16 mg/L (D1) and to 2506.53 mg/L (D2). Total solids, COD, temperature, and pH analyses were performed, and the biochemical oxygen demand (BOD) was estimated from the COD values. The best performance in the reduction of the organic matter was observed for Polygonum sp. (87.5% COD and 79.6% BOD) and Eichhornia paniculata (90% COD and 83.7% BOD) at dilution D1, on the 8th day of the experiment. However, the highest total solids removal was observed for Polygonum sp. (32.2%), on the 4th day, at dilution D2. The total solid (TS) concentration has also increased starting from the 8th day of the experiment was observed which may have been due to the development of mosquito larvae and their mechanical removal by sieving, thus changing the steady state of the experimental systems. The macrophytes Polygonum sp. and E. paniculata were considered suitable for the reduction of organic matter of DW using constructed wetlands.     

Chlorella sorokiniana immobilized on the biomatrix of vegetable sponge of Luffa cylindrica: a new system to remove cadmium from contaminated aqueous medium

A new sorption system of microalgal cells immobilized on the biostructural matrix of Luffa cylindrica for sequestering cadmium is reported. Free and immobilized Chlorella sorokiniana removed cadmium from 10 mgl(-1) solution at the efficiency of 92.7% and 97.9% respectively. Maximum cadmium sorption was observed to be 39.2 mgg(-1) at equilibrium (C(eq)) of 112.8 mgl(-1) by immobilized microalgal biomass as compared to 33.5 mgg(-1) at C(eq) of 116.5 mgl(-1) by free biomass from initial concentration of 150 mgl(-1). In continuous liquid flow column, the cadmium sorption capacity of immobilized C. sorokiniana was 192 mgg(-1), which was 73.2% of the total metal passed in 51.5 l. Metal desorption with 0.1 M HCl was 100% and the desorbed immobilized system was reusable with a similar efficiency in the subsequent cycle.     

Bioabsorption of chromium from retan chrome liquor by cyanobacteria

The bioaccumulation of chromium from retan chrome liquor by Spirulina fusiformis was investigated under laboratory as well as field conditions. At the optimal conditions, metal ion uptake increased with initial metal ion concentration up to 300 mg/l. The effect on various physico-chemical parameters like total solids (TS), total dissolved solids (TDS), total suspended solids (TSS), chlorides, sulphates, phenols, biochemical oxygen demand (BOD) and chemical oxygen demand (COD) and biochemical studies related to biomass, chlorophyll-a and protein were also carried out. The present study indicates that S. fusiformis is very effective in removal of chromium (93–99%) besides removing other toxicants from retan chrome liquor. The sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and FTIR studies indicate the interaction/complexation between Cr and alga. The mechanism involved in bioaccumulation of chromium is also discussed. The process when upgraded can be applied for detoxification of tannery effluents.     

Optimization of a biological process for treating potato chips industry wastewater using a mixed culture of Aspergillus foetidus and Aspergillus niger

Potato chips industry wastewater was collected and analyzed for biochemical oxygen demand (BOD), chemical oxygen demand (COD), total suspended solids (TSS) and total carbohydrates. Two Aspergillus species, A. foetidus and A. niger, were evaluated for their ability to grow and produce biomass and reduce the organic load of the wastewater. A. foetidus MTCC 508 and A. niger ITCC 2012 were able to reduce COD by about 60% and produce biomass 2.4 and 2.85 gl(-1), respectively. Co-inoculation of both Aspergillus strains resulted in increased fungal biomass production and higher COD reduction than in individual culture at different culture pH. pH 6 was optimum for biomass production and COD reduction. Amendment of the wastewater with different N and P sources, increased the biomass production and COD reduction substantially. Under standardized conditions of pH 6 and amendment of wastewater with 0.1% KH2PO4 and 0.1% (NH4)2 SO4, a mixed culture gave 90% reduction in COD within 60 h of incubation.     

Processes impacting on benzene removal in vertical-flow constructed wetlands

The overall aim of this research project was to reduce low molecular weight hydrocarbons such as benzene in produced wastewaters. Over 30 months of research was conducted to test the treatment performance in terms of benzene removal in vertical-flow constructed wetlands. Based on an influent concentration of 1 g L(-1) benzene, the results show mean benzene removal efficiencies between 88.71% and 89.77%, and 72.66% and 80.46% for indoor and outdoor constructed wetlands, respectively. A statistical analysis indicated that the five days at 20 degrees C N-allylthiourea biochemical oxygen demand (BOD(5)), chemical oxygen demand (COD), nitrate-nitrogen (NO(3)-N), dissolved oxygen (DO) and electric conductivity (EC) values of the effluent were positively correlated with the effluent benzene concentrations following the order COD>DO>EC>NO(3)-N>BOD(5), and negatively correlated according to the order pH>redox potential (redox)>temperature (T)>turbidity. No strong relationships between benzene and the variables ortho-phosphate-phosphorus (PO(4)(3-)) and ammonia-nitrogen (NH(4)-N) were recorded.     

An integrated treatment system for coffee processing wastewater using anaerobic and aerobic process

The experiment was conducted to develop an integrated treatment system for coffee processing wastewater (CPWW) through the combination of biomethanation with aeration and wetland plants treatment. The biomethanation was carried out at different hydraulic retention times (HRTs) using upflow anaerobic hybrid reactor (UAHR) and 18 h of HRT was found to be optimum. The maximum biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total solids (TS) reduction were 66.0%, 61.0% and 58.0%, respectively with organic loading rate of 9.55 kg m^?3 day^?1. The reduction of pollution load of the wastewater by microbial action augmented by aeration resulted in the reduction of electrical conductivity (EC), BOD, COD, and total solids (TS). Continuous aeration of wastewater resulted in maximum reduction of BOD (74.6%), COD (68.6%) and TS (49.3%). The wetland plant, Typha latifolia reduced 85.4% and 78.0% of BOD and COD, respectively in biomethanated cum aerated CPWW.     

In situ removal of contaminated suspended solids from a pond by filtration

Suspended solids (SS) which have been discharged into ponds, lakes, and enclosed sea areas from shores and rivers absorb various substances such as heavy metals and nutrients. In this study, a small upward filtration system was developed to remove contaminated SS from the water. The system consisted of a main body with a flotation device, three pumps, two float sensors, solar panels and batteries. The filter medium consisted of a nonwoven geotextile with a thickness of 5 mm. The pilot experiment was carried out in Shimizu Utozaka pond in Japan. SS, chemical oxygen demand (COD) and total phosphorus (T-P) removal efficiencies of 88.5%, 56.5% and 64.2% were obtained, respectively. In addition, the estimation of pollutant removal was determined from the amount of removed SS. This calculation enables not only the design of filtration systems for future individual cases, but also quantitative evaluation for the effect of restoration.     

Treatment of sewage water from tourist areas by anaerobic fixed-bed reactor

A laboratory-scale anaerobic fixed-bed reactor, operating at ambient temperature (30 to 35°C), was used to treat sewage water from tourist areas in Cuba at hydraulic retention times (HRT) ranging from 4 to 72 h. The total chemical oxygen demand (T-COD), total biological oxygen demand (T-BOD) and total suspended solids removal varied between 30 and 80%, 40 and 95% and 25 and 80%, respectively. Total and faecal coliforms were reduced by 98.1 to 99.9% and by 99.0% to 99.9% respectively, despite the marked decrease in HRT from 72 to 4 h.     

Characterization and structure elucidation of 12-hydroxyoctadec-cis-9-enoic acid in Jatropha gossypifolia and Hevea brasiliensis seed oils: a rich source of hydroxy fatty acid

The seed oils containing hydroxy fatty acids are being used in various industries such as, in the production of nylon-11, in the manufacture of multi-purpose greases, as good anti-rust, new additives in water-soluble cutting fluids, and antimicrobial activity of various derivatives of ricinoleic acid polymers. Jatropha gossypifolia and Hevea brasiliensis seed oils were found to contain 18.5% and 18.0% of 12-hydroxyoctadec-cis-9-enoic acid (ricinoleic acid), respectively. The identification and characterization was based on UV, FTIR, (1)H NMR, (13)C NMR, MS, GC analysis and chemical degradations.     

Effects of 2,4-dichlorophenol on activated sludge

The effects of 2,4-dichlorophenol (2,4-DCP) on both acclimated and unacclimated activated sludge were investigated in batch reactors. The IC(50) values on the basis of maximum specific growth rate ( micro(m)), percent chemical oxygen demand (COD) removal efficiency and sludge activity were found to be 72, 60 and 47 mg l(-1), respectively, for unacclimated culture. The percent COD removal efficiencies of unacclimated culture were affected adversely, even at low concentrations, whereas culture acclimated to 75 mg 2,4-DCP l(-1) could tolerate about 200 mg 2,4-DCP l(-1)on the basis of COD removal efficiency. Although yield coefficient values of unacclimated culture increased surprisingly to very high values with the addition of 2,4-DCP, a linear decrease with respect to 2,4-DCP concentrations was observed for acclimated culture. Although no removal was observed with unacclimated culture, almost complete removal of 2,4-DCP up to a concentration of 148.7 mg l(-1) was observed with acclimated culture. It was showed that the culture could use 2,4-DCP as sole organic carbon source, although higher removal efficiencies in the presence of a readily degradable substrate were observed. Culture acclimated to 4-chlorophenol used 2,4-DCP as sole organic carbon source better than those acclimated to 2,4-DCP.     

Palm oil mill effluent treatment by a tropical marine yeast

Palm oil mill effluent (POME), from a factory site in India contained about 250,000 mg l(-1) chemical oxygen demand (COD), 11,000 mg l(-1) biochemical oxygen demand, 65 mg l(-1) total dissolved solids and 9000 mg l(-1) of chloroform-soluble material. Treatment of this effluent using Yarrowia lipolytica NCIM 3589, a marine hydrocarbon-degrading yeast isolated from Mumbai, India, gave a COD reduction of about 95% with a retention time of two days. Treatment with a chemical coagulant further reduced the COD and a consortium developed from garden soil clarified the effluent and adjusted the pH to between 6 and 7. The complete treatment reduced the COD content to 1500 mg l(-1) which is a 99% reduction from the original.     

Assessment of characteristics and biological treatment technologies of Jordanian wastewater

Demand for wastewater treatment facilities will increase as Jordan's population grows. In addition, currently available systems of treatment desperately need upgrades in capacity or supplementary systems; especially in the Amman-Zarqa region. Overall; based on the current wastewater flow rates; approximately 85% of the collected sewerage is treated in stabilization ponds, 10% in trickling filters, and 5% in activated sludge systems. This study was carried out to analyze and identify the properties of Jordanian wastewater; compare it to the common characteristics internationally known; and couple that with a proposal of an appropriate treatment technology. Five treatment plants were selected to achieve the objectives of this study; the flow rate of which constitutes approximately 80% of the total treated wastewater in Jordan, based on the design capacity. The study concluded that the wastewater generated in Jordan is classified as strong in terms of total dissolved solids content, total suspended solids content, and chemical and biochemical oxygen demands (COD and BOD). The efficiency of the selected technologies in removing dissolved solids from wastewater was low while it was reasonably high in terms of suspended solids removal. The technology achieving highest percent removals of BOD and solids was that of activated sludge and its modifications. Based on the factors considered in evaluating and selecting unit operations and processes, the activated sludge and its modifications are probably the process technology that should be used in treating Jordanian domestic wastewaters.     

Performance of subsurface flow constructed wetland taking pretreated swine effluent under heavy loads

Subsurface flow constructed wetlands (SSFCW) subjected to changing of loading rates are poorly understood, especially when used to treat swine waste under heavy loads. This study employed a SSFCW system to take pretreated swine effluent at three hydraulic retention times (HRT): 8.5-day HRT (Phase I), 4.3-day HRT (Phase II), and 14.7-day HRT (Phase III). Results showed that the system responded well to the changing hydraulic loads in removing suspended solids (SS) and carbonaceous oxygen demands. The averaged reduction efficiencies for four major constituents in the three phases were: SS 96-99%, chemical oxygen demand (COD) 77-84%, total phosphorus 47-59%, and total nitrogen (TN) 10-24%. While physical mechanisms were dominant in removing pollutants, the contributions of microbial mechanisms increased with the duration of wetland use, achieving 48% of COD removed and 16% of TN removed in the last phase. Water hyacinth made only a minimal contribution to the removal of nutrients. This study suggested that the effluent from SSFCW was appropriate for further treatment in land applications for nutrient assimilation.