Biological Treatment Methods Research Articles

Environmental and Health Consequences of Distillery Wastewater and Ways to Tackle: A Review

Liquid sludge, due to its low pH, elevated temp, dark brown hue, high ash content, a high proportion of organic and inorganic dissolved materials, and high biochemical oxygen demand, distillery wastewater is one of the most harmful pollutants that must be disposed off. The brightly colourful quality of the washed wash, which may obscure sunlight and reduce water oxygenation through photosynthesis, is the first way that the washed wash polluted the water bodies. This is harmful to aquatic life. The second problem is that it has a high contamination load that may lead to eutrophication in polluted water sources. Because of the numerous industrial uses of ethanol, including in chemicals, medicines, cosmetics, drinks, food, and perfumes, distilleries are expanding all over the world. The industrial manufacture of ethanol by fermentation results in the release of significant amounts of elevated BOD and COD levels. The food stock and different elements of the ethanol manufacturing process affect its features. To have a better understanding of the phenomena, the function of numerous microorganisms and their enzymes in wastewater treatment has been addressed. Without treatment, distillery wastewater can seriously endanger aquatic life by reducing the amount of dissolved oxygen in the water currents it enters. This paper includes a thorough analysis of current biological treatment methods as well as a list of issues related to distillery wastewater concerns.

Applicability of biological wastewater treatment for various industries

Biological treatment methods are used to remove organic and some inorganic substances from wastewater using the simplest organisms that use these substances for nutrition, breaking them down using cellular processes. The article deals with the aerobic, anaerobic and anoxic stages of biological wastewater treatment. Their differences are explained and the best way to use biological processes is analyzed according to the type of industry/production. At wastewater treatment plants, anaerobic treatment is often used at first to remove a significant part of organic substances from wastewater before sending them for further aerobic treatment. Aerobic treatment is effective for various types of wastewater, especially with lower biochemical oxygen demand (BOD) and chemical oxygen demand (COD). A comparative analysis of wastewater composition from food, oil and gas processing, pharmaceutical and pulp and paper industries was carried out. In the presence of organic compounds, the technology is chosen depending on the total organic matter content or the total COD content, which characterizes the total organic matter in water. A combination of anaerobic and aerobic methods is possible, if a discharge into the sewer system or into water bodies is required. The grounds for the application of biological wastewater treatment of these industries are given.

Laccase producing bacteria influenced the high decolorization of textile azo dyes with advanced study

Recent year, bacterial laccases are increasing interest in the field of industry and environmental applications especially decolorization of azo dyes. In industry, the dyes are present in stable nature including chemicals and lights. Due to these defects, the novel approaches are needed to removal of dyes before discharging into the environment. Among the various technologies, biological treatment methods and their strategies are very important, because of the decolorization and detoxification. Consecutively, biological mediated dyes removal are emerged with high potential especially microbes. Microbial laccases creates up new opportunities for their commercial applications. In this study, laccases were produced from Bacillus cereus (B. Cereus) and Pseudomonas parafulva (P. parafulva) by sub merged fermentation. For immobilization, the produced laccases were subjected to purify using 80% saturated ammonium sulphate and followed by dialysis. Then, crude laccases were immobilized through copper-alginate entrapment method. The maximum immobilized enzyme activity of the immobilized laccases were shown pH 8 at 50 °C and pH 7 at 40 °C for B. Cereus and P. parafulva respectively. In contrast, the normal enzyme activity was pH 10 at 40 °C and pH 8 at 40 °C were indicated for Bacillus cereus and P. parafulva respectively. Next, the free and immobilized laccases were performed the decolorization of three azo dyes T-blue, yellow GR and orange 3R, and exhibited that the 91.69 and 89.21% of Orange 3R were completely decolorized by both the B. Cereus and P. parafulva laccases when compared with free laccases enzymes. The confirmation of decolorization was monitored by UV–vis spectroscopy and FTIR spectroscopy, which clearly confirm the changes of peaks when compared with normal laccases. Finally, we have concluded that the B. Cereus and P. parafulva laccases are very important in azo dye decolorization and these used in future biological treatment of dyeing effluents.

Assessing efficiency and economic viability in treating leachates emanating from the municipal landfill site at Gazipur, India.

The leachates emanating from the landfills are high in organic loads and thus become potential sources of contamination for both surface and groundwater. As the landfill ages, the nature of leachate changes from acidic to alkaline. The change in pH level affects the chemical oxygen demand (COD)/biochemical oxygen demand (BOD) ratio and when it is less than 0.63, chemical treatments are more effective over the biological treatment methods such as upflow anaerobic sludge blankets (UASB). The existing literature suggests coagulation-flocculation and advanced oxidation process (Fenton) as effective methods for treating wastewater but no comparison of the two are available. Thus, the present study attempts to identify the most efficient coagulants out of ferric chloride (FeCl3), ferrous sulphate (FeSO4) and alum [Al2(SO4)3]. Ferric chloride leading to 99% colour removal, 98% COD removal, 99% decrease in total organic carbon, 94.3% removal in NH3-N and 91.4% removal in total Kjeldahl nitrogen is observed to be the most efficient coagulant and surprisingly, proves to be even better than Fenton. To understand the field applicability of the two treatment procedures, coagulation with FeCl3 and Fenton are compared with the UASB method which is currently employed at Gazipur landfill site, Delhi. With lesser operational cost than UASB, both FeCl3 and Fenton perform better on cost-efficiency scale. Switching from in-suit UASB method to the FeCl3 method of treatment may result in decreasing the operational cost by 71.9% and to conventional Fenton may result in decreasing the operational cost by 76.8%.

Pilot-scale study based on integrated fixed-film activated sludge process for cement industrial wastewater treatment

Due to the lack of freshwater resources in Egypt, cement wastewater treatment was performed to widen the range of the water used in irrigation to face the massive future water scarcity. In this study, integrated fixed-film activated sludge (IFAS) was used as a biological treatment method. A laboratory pilot was established as a simulation of the IFAS process. The scale-pilot consists of a primary sedimentation tank, an IFAS tank equipped with an air blower, and a final settling tank. Three experimental attempts were performed using 3 different bio-carriers. In the first trial, Luffa sponges were used as natural bio-carriers and polyurethane sponges (PU) as artificial bio-carriers in the second trial, in addition to a combination between Luffa and PU sponges as a hybrid bio-carrier in the third trial. After analyzing the physicochemical properties of wastewater at the national research center in Cairo, the removal efficiency of TSS (total suspended solids), COD (chemical oxygen demand) , BOD(biological oxygen demand), TN (total nitrogen), and TP (total phosphorous) was 94.5%, 87.8%, 90.8%, 75.9%, and 69.4%, respectively in case of using the combination between Luffa and PU sponges. It can be concluded that using IFAS process was effective for cement wastewater treatment and the effluent wastewater met the Egyptian code limitations for reuse in agriculture purposes.

A comprehensive review on application of bioreactor for industrial wastewater treatment.

In the recent past, wastewater treatment processes performed a pivotal role in accordance with maintaining the sustainable environment and health of mankind at a proper hygiene level. It has been proved indispensable by government regulations throughout the world on account of the importance of preserving freshwater bodies. Human activities, predominantly from industrial sectors, generate an immeasurable amount of industrial wastewater loaded with toxic chemicals, which not only cause dreadful environmental problems, but also leave harmful impacts on public health. Hence, industrial wastewater effluent must be treated before being released into the environment to restrain the problems related to industrial wastewater discharged to the environment. Nowadays, biological wastewater treatment methods have been considered an excellent approach for industrial wastewater treatment process because of their cost-effectiveness in the treatment, high efficiency and their potential to counteract the drawbacks of conventional wastewater treatment methods. Recently, the treatment of industrial effluent through bioreactor has been proved as one of the best methods from the presently available methods. Reactors are the principal part of any biotechnology-based method for microbial or enzymatic biodegradation, biotransformation and bioremediation. This review aims to explore and compile the assessment of the most appropriate reactors such as packed bed reactor, membrane bioreactor, rotating biological contactor, up-flow anaerobic sludge blanket reactor, photobioreactor, biological fluidized bed reactor and continuous stirred tank bioreactor that are extensively used for distinct industrial wastewater treatment.

Bioremediation of industrial effluents: A synergistic approach.

Industrial wastewater consists of inorganic and organic toxic pollutants that pose a threat to environmental sustainability. The organic pollutants are a menace to the environment and life forms than the inorganic substances and pose teratogenic, mutagenic, carcinogenic, and other serious detrimental effects on the living entities, moreover, they have a gene-altering effect on aquatic life forms and affect the soil fertility and quality. Removal of varying effluents having recalcitrant contaminants with conventional treatment technologies is strenuous. In contrast to physical and chemical methods, biological treatment methods are environmentally friendly, versatile, efficient, and technically feasible with low operational costs and energy footprints. Biological treatment is a secondary wastewater treatment system that utilizes the metabolic activities of microorganisms to oxidize or reduce inorganic and organic compounds and transform them into dense biomass, which later can be removed by the sedimentation process. Biological treatment in bioreactors is an ex situ method of bioremediation and provides the benefits of continuous monitoring under controlled parameters. This paper attempts to provide a review of bioremediation technologies discussing most concerning widespread bioreactors and advances used for different industrial effluents with their comparative merits and limitations.

A review on recent disposal of hazardous sewage sludge via anaerobic digestion and novel composting

The high investment cost required by modern treatment technologies of hazardous sewage sludge such as incineration and anaerobic digestion have discouraged their application by many developing countries. Hence, this review elucidates the status, performances and limitations of two low-cost methods for biological treatment of hazardous sewage sludge, employing vermicomposting and black soldier fly larvae (BSFL). Their performances in terms of carbon recovery, nitrogen recovery, mass reduction, pathogen destruction and heavy metal stabilization were assessed alongside with the mature anaerobic digestion method. It was revealed that vermicomposting and BSFL were on par with anaerobic digestion for carbon recovery, nitrogen recovery and mass reduction. Thermophilic anaerobic digestion was found superior in pathogen destruction because of its high operational temperature. Anaerobic digestion also had proven its ability to stabilize heavy metals, but no conclusive finding could confirm similar application from vermicomposting or BSFL treatment. However, the addition of co-substrates or biochar during vermicomposting or BSFL treatment may show synergistic effects in stabilizing heavy metals as demonstrated by anaerobic digestion. Moreover, vermicomposting and BSFL valorization had manifested their potentialities as the low-cost alternatives for treating hazardous sewage sludge, whilst producing value-added feedstock for biochemical industries.

Nutrient requirement of tannery wastewater containing tannins

Biological wastewater treatment methods are extensively used in the treatment of industrial effluents among which Activated Sludge Process (ASP) holds a prominent position. To carry out the degradation of organic matter, the micro-organisms present in the activated sludge need sufficient amount of nutrients and oxygen in the aerobic treatment process. Hence, this study was undertaken to assess and optimize the nutrient requirement in the treatment of vegetable tanning process wastewater (VTW) generated from tanneries. The characterization of VTW revealed that the observed Biochemical Oxygen Demand (BOD):Nitrogen (N):Phosphorus (P) ratio of VTW was 100:1.42:0.07, which is deficient in both N and P. Aerobic reactor study was conducted with BOD:N:P ratio of 100:1.42:0.07, 100:5:0.1, 100:5:1, 100:5:3 and 100:5:5 separately. For N:P of 5:0.1, removal efficiencies of BOD 5 , COD and tannin were 49.0 %, 37.3 % and 30.2 %, respectively, whereas, for N:P of 5:3, BOD 5 ,COD and tannin removal efficiency was 59.7 %, 50.9 % and 38.0 %, respectively. However, further increasing the N:P ratio to 5:5, BOD 5 ,COD and tannin removal efficiencies were 60.9 %, 51.2 % and 38.7 %, respectively. It was observed from the results that for N:P ratio of 5:3 to 5:5, the improvement in removal efficiencies was marginal. Hence, BOD:N:P ratio of 100:5:3 was considered as optimum Respirometry study revealed that oxygen uptake was 62.5 mg O 2 during the 24 h and 18 % of MLSS growth was observed. From modified Stover–Kincannon model the kinetic constants U max of 3.74 g/L day and K B of 54.08 g/L.d were arrived at; The k value was obtained from first order and zero order equation was 16.95 mg/L h −1 and 0.026 h −1 , respectively for tannin as substrate for the optimized ratio BOD:N:P ratio of 100:5:3. This study emphasizes that proper balance of N and P is needed for synthesis of sufficient biomass for degradation in biological treatment.

Removal of emerging micropollutants originating from pharmaceuticals and personal care products (PPCPs) in water and wastewater by advanced oxidation processes: A review

Because of their intrinsic potential to produce metabolic effects on the human body at smaller concentrations, pharmaceuticals and personal care products (PPCPs) are a distinct category of emerging environmental pollutants. Due to their widespread intake, limited metabolic capacity, and indecorous disposal, PPCPs pollutants are commonly found in water supplies and wastewater treatment plants. If partly oxidized PPCPs are introduced into wastewater treatment plants, they will disrupt biological wastewater treatment procedures. As a result, traditional wastewater treatment plants are inadequate for PPCPs elimination. PPCPs have been effectively eliminated using advanced oxidation methods such as electrochemical oxidation, ultrasonication, and ionizing radiation. This review summarizes recent studies on the removal of PPCPs by advanced oxidation processes, as well as knowledge useful for applying these processes in water and wastewater treatment. The degradation of different classes of PPCPs has been reviewed to analyze (i) significant factors — initial concentration of PPCPs, ultrasonication power, radiation dose, current density, temperature, pH, time, and effect of catalysts; (ii) degradation efficiency of the processes when applied in combination with other advanced oxidation methods; (iii) key factors that affect the removal of PPCPs based on their properties. In addition, suggestions for future studies on advanced oxidation methods and their limitations were discussed. Overall, this review could aid in providing an in-depth understanding of the current research trends concerning PPCPs and advanced oxidation processes. • Removal of PPCPs using conventional wastewater treatment techniques is difficult. • Ultrasonication in combination with other AOP enhanced degradation efficiency. • Ionizing radiation in tune with biological treatment methods boosted degradation. • Electrochemical oxidation is better recommended as final step in water treatment.

Textile Industry Effluent Treatment Techniques

Dyes and other chemicals laden wastewater is a main environmental concern for increasing the textile industries in many parts of the world. Textile industries consume different kinds of manmade dyes or other chemicals and release huge extents of highly polluted water into the environment. This excessive dye laden wastewater has great impacts on photosynthetic activity in aquatic plants and animals, for example, fish. It may also affect human health due to the presence of components like heavy metals and chlorine in manmade dyes. Thus, wastewater effluent from textile industries must be treated before discharge into the water body. Treatment technologies observed in this review paper include biological treatment methods (fungi, algae, bacteria, and microbial fuel cells), chemical treatment methods (photocatalytic oxidation, ozone, and Fenton’s process), and physicochemical treatment methods (adsorption, ion exchange, coagulation, and filtration). This review also includes the hybrid treatment methods and their cost per m3 of treated wastewater analysis. There are alternative wastewater treatments systems at different steps of effluent generated from the textile operational unit recommend in this review work.

Roles of autoinducer-2 mediated quorum sensing in wastewater treatment

Abstract Quorum sensing (QS) is considered to be a promising regulation method for biological wastewater treatment (WWT) due to its regulation in extracellular substances (EPS) production, biofilm formation, granulation, colonization and bacterial activity and stability. Recently, autoinducer-2 (AI-2), a kind of interspecies communication QS signal molecule, is being increasingly reported for its roles in regulating bacterial gene expression and aggregation. Consequently, AI-2 mediated QS system is considered as a promising regulatory approach in WWT processes. This article systematically reviews the effects of AI-2-mediated QS system on bacterial behavior and its high potential for real-world applications in different WWT systems. Given the extensive presence of AI-2, AI-2 mediated QS could cooperate with other signal molecules in WWT processes, which suggests that the interactions among multiple signal molecules might be underestimated in the previous studies. The differences between AI-2 and AHL signaling molecules are also compared. Furthermore, the attempts at AI-2 regulated QS in pollution control of different WWT systems are summarized, while some challenges and defects still require targeted research in the future.

Investigation of microalgal treatment for poultry slaughterhouse wastewater after the dissolved air flotation unit

Meat and meat products are some of the primary consumption products required for the continuation of life. The world population accessed over 7.5 billion that means the demand for food is increasing every day. Slaughterhouses and integrated meat facilities are being rapidly developed and established to meet meat and meat product requirements. In slaughterhouse poultry plants, high amounts of water are utilized for the meatpacking process. The poultry slaughterhouse wastewaters contain high levels of organic solids such as fat, blood, suspended matter, and dissolved protein, which can be treated using physical, chemical, and biological treatment methods. In this study, the treatment of poultry slaughterhouse wastewater preliminarily treated by dissolved air flotation, with microalgae culture (Chlorella Vulgaris) development, unlike traditional treatments, was investigated. Chemical oxygen demand and total suspended solids parameters for wastewater treatment have been monitored for 15 days of incubation. 0.8, 4, 8, 12, and 20% by volume algae were applied for slaughterhouse wastewater, and the optimum amount of algal inoculation was determined after 15 days. When the removal efficiencies were examined, the most appropriate amount of inoculation rate with 76 % chemical oxygen demand removal and 87% algal growth (as total suspended solids) was selected as 12%.

Veterinary pharmaceuticals in aquaculture wastewater as emerging contaminant substances in aquatic environment and potential treatment methods

Veterinary pharmaceuticals are still unregulated and their residues in the environment have the potential to cause considerable impact on ecosystems. Water pollution due to veterinary pharmaceuticals gained worldwide attention because they deteriorate the water quality and impart a toxic effect on living organisms. Therefore, the effective aquaculture wastewater treatment for veterinary pharmaceuticals removal before releasing into the environment is necessary to prevent the risk of environmental contamination and subsequent negative health and economic impacts on both the human and aquaculture industry. This review provides an overview of currently available methods to remove veterinary pharmaceuticals available in aquaculture wastewater while reviewing some methods already studied for other types of pharmaceuticals but possible to use in aquaculture in the future and the scope of the review has been limited to aquaculture antibiotics used as veterinary medicines. Several water refinement techniques such as conventional mechanical, chemical, biological and physical wastewater treatment methods are practiced but they are not with suitable efficiency. Several studies were published covering small or special sections of water pollution by pharmaceuticals. But most of these studies have been done targeting to remove the antibiotics coming from hospital effluent, livestock or animal farm, and veterinary practices. There are very few research studies done specifically for aquaculture wastewater treatment against veterinary pharmaceuticals. Therefore, more attention and efforts must be given to this topic to be developed and to know all details concerning the toxicity of veterinary pharmaceuticals and how they can be removed from the aquaculture wastewaters.

Advances in Biological Nitrogen Removal of Landfill Leachate

With the development of economy and the improvement of people’s living standard, landfill leachate has been increasing year by year with the increase in municipal solid waste output. How to treat landfill leachate with high efficiency and low consumption has become a major problem, because of its high ammonia nitrogen and organic matter content, low carbon to nitrogen ratio and difficult degradation. In order to provide reference for future engineering application of landfill leachate treatment, this paper mainly reviews the biological treatment methods of landfill leachate, which focuses on the comparison of nitrogen removal processes combined with microorganisms, the biological nitrogen removal methods combined with ecology and the technology of direct application of microorganisms. In addition, the mechanism of biological nitrogen removal of landfill leachate and the factors affecting the microbial activity during the nitrogen removal process are also described. It is concluded that the treatment processes combined with microorganisms have higher nitrogen removal efficiency compared with the direct application of microorganisms. For example, the nitrogen removal efficiency of the combined process based on anaerobic ammonium oxidation (ANAMMOX) technology can reach more than 99%. Therefore, the treatment processes combined with microorganisms in the future engineering application of nitrogen removal in landfill leachate should be paid more attention to, and the efficiency of nitrogen removal should be improved from the aspects of microorganisms by considering factors affecting its activity.

Physiochemical, Instrumental and thermal characterization of the post coagulation sludge from paint industrial wastewater treatment

Most sludge generated from water treatment plants is toxic. One of such sludge as focused on this work is paint wastewater treatment sludge from coagulation-flocculation process. Due to the problem of sludge disposal, post coagulation sludge was characterized via physical, instrumental and thermal characterization to suggest possible treatment methods to avert disposal of toxic wastes into the environment. Post coagulation sludge recovered after jar-test experiment has high settleability index with Sludge Volume Index ˂ 80. The best sludge volume index of 11 was obtained at sludge solid concentration of 2264.3 mg/l. Post coagulation sludge has pH of 6.83, Volatile Solid of 77% of the total solid (2210 mg/l) and Carbon: Nitrogen value of 26:1. The Biological Oxygen Demand - Chemical Oxygen Demand ratio of 0.7 shows that post coagulation sludge is moderately toxic. CHNX analysis shows that post coagulation sludge contains majorly calcium (35.54%), oxygen (30.2%), carbon (9.25%) and sodium (7.74 (aluminum (3.05%), silicon (3.14%) and titanium (3.69%)) and some trace elements. The prominent functional groups include =C–H in-plane bending of alkene aliphatic compound at 1403 cm−1, carboxylic group at 3000 cm−1, cellulose –OH stretching vibration group at 3476 cm−1,NH stretching of amine group within 3300–3500 cm−1 among others in trace forms. 10% reduction in weight was observed via thermo-gravimetric analysis (TGA). The mid-point glass temperature was 45 °C, while the melting point was 175 °C. In addition, PCS turns to ashes above 300 °C. Based on the results; Post coagulation sludge can be managed via, biological treatment methods, anaerobic digestion and by thermal degradation.

Physico-chemical and biological treatment strategies for converting municipal wastewater and its residue to resources

An increase in urbanization and industrialization has not only contributed to an improvement in the lifestyle of people, but it has also contributed to a surge in the generation of wastewater. To date, conventional physico-chemical and biological treatment methods are widely used for the treatment of wastewater. However, the efficient operation of these systems require substantial operation and maintenance costs, and the application of novel technologies for the treatment and disposal of sludge/residues. This review paper focuses on the application of different treatment options such as chemical, catalyst-based, thermochemical and biological processes for wastewater or sludge treatment and membrane-based technologies (i.e. pressure-driven and non-pressure driven) for the separation of the recovered products from wastewater and its residues. As evident from the literature, a wide variety of treatment and resource recovery options are possible, both from wastewater and its residues; however, the lack of planning and selecting the most appropriate design (treatment train) to scale up from pilot to the field scale has limited its practical application. The economic feasibility of the selected technologies was critically analyzed and the future research prospects of resource recovery from wastewater have been outlined in this review.

A Review of Processes for Removing Antibiotics from Breeding Wastewater.

Antibiotic pollution has become an increasingly serious issue due to the extensive application of antibiotics, their resistance to removal, and the harmful effects on aquatic environments and humans. Breeding wastewater is one of the most important sources of antibiotics in the aquatic environment because of the undeveloped treatment systems in breeding farms. It is imperative to establish an effective antibiotic removal process for breeding wastewater. This paper reviews the treatment methods used to remove antibiotics from breeding wastewater. The mechanisms and removal efficiency of constructed wetlands, biological treatments, advanced oxidation processes (AOPs), membrane technology, and combined treatments are explained in detail, and the advantages and disadvantages of the various treatment methods are compared and analyzed. Constructed wetlands have high removal rates for sulfonamide (SM), tetracycline (TC), and quinolone (QN). The antibiotic removal efficiency of biological treatment methods is affected by various processes and environmental factors, whereas AOPs and combined treatment methods have better antibiotic removal effects. Although it has broad application prospects, the application of membrane technology for the treatment of antibiotics in breeding wastewater needs further research.

Performance of temperature changes and dosage for enhancement of nitrogen and phosphorus removal from wastewater: A comparative study

The development in Iraq, in addition to the increase in the population and the increase in the standard of living, has led to a marked increase in the demand for water, as the shortage of fresh water resources has become a problem that concerns specialists and decision-makers as it affects the water deficit, especially in the provision of drinking water (the basis of life) in addition to other requirements such as agriculture. Which led to the search for other possible solutions available. One of these solutions is the reuse of treated wastewater in agriculture or any other uses to save fresh water and expand agricultural areas after removing high concentrations of nutrients such as nitrogen and phosphorous. The aim of the study is to improve the performance of the treatment method used by the sewage treatment plant to achieve the removal of nutrients from the treated water. The dual use of a biological treatment and chemical precipitation process to remove phosphorous compounds from wastewater was studied. To avoid instability in the biological treatment method due to temperature changes during the year, especially in the summer. The obtained wastewater treatment plant validation was verified by applying the existing plant planning in GPS-X 8.0 modeling and simulation software, by combining biological and chemical removal methods to improve the performance of a wastewater treatment plant in Khairy in Al Diwaniyah, Iraq (KWWTP). The results showed that a series of conditions for anaerobic, oxygen and aerobic reactors help to remove biological nutrients efficiently. The concentration of COD, BOD and TSS were below the permissible environmental parameters. The removal rate of nitrogen as N-NH3 is 92.96; 94.93; 97.60% respectively. The phosphorous removal rate is 80.22, 86.55, 92.30 respectively Except for the release of nitrogen and phosphorous compounds during the summer (July and August) due to the sensitivity of phosphorous-containing organisms to the influence of temperature. The increasing concentrations of phosphorous produced in the summer were treated by adding doses of chemicals (alum) at different stages of the wastewater treatment plant, and the required dose of Alum ranges in the range of 0.5-0.9 kgAl / kg P, according to the dose strategy that achieves the highest efficiency of the KWWTP.

In-situ methane enrichment of biogas from anaerobic digestion of palm oil mill effluent by addition of zero valent iron (ZVI)

Palm oil mill effluent (POME) is a wastewater effluent that is generated from palm oil milling. Treatment of POME, especially using biological treatment methods, is a challenge as it contains high amounts of organic and sulfur compounds, and it is highly acidic. In this research, the effects of zero-valent iron (ZVI) on the enhancement of methane production from POME via anaerobic digestion were investigated. Furthermore, to identify the reactor operation modes that were suitable for the addition of ZVI, anaerobic digestion of POME was tested in three reaction configurations: batch reactor, fed-batch reactor, and continuous stirred-tank reactor (CSTR). In the batch mode, where acidic POME was fed with 16 g/L of ZVI dose just once, methane production increased by 74%. However, as the oxidation of ZVI under anaerobic conditions led to the production of hydroxyl ions, the pH of the medium continuously increased from approximately 7 to 9, which is not suitable for methanogenesis. In the fed-batch mode that involved intermittent feeding of acidic POME, the pH of the culture media was maintained at 6.8. This is because the extra hydroxyl ions generated from the oxidation reaction of ZVI tended to neutralize the acids in the feeding substrate. In addition, ZVI promoted the production of methane from POME and increased the average methane content in biogas from 62% to 76%. In the CSTR mode, which involved continuous feeding of acidic POME, ZVI increased methane production by 86% (from 1.79 to 3.32 L/day), methane content in biogas from 60 to 75%, and total chemical oxygen demand (tCOD) removal efficiency from 78 to 89 to 88–95%. Thus, the addition of ZVI can be a potential strategy for in-situ methane enrichment of biogas by anaerobic digestion of POME. This is because ZVI acts as a buffer for acid generation and provides extra electrons, ferrous ions, and ferric ions, which promote key microbial activities in the anaerobic digestion process.