Small Wastewater Treatment Research Articles

Application of an Anaerobic–Anoxic–Oxic–Oxic (AAO/O) Model to the Treatment of Real Domestic Wastewater

Untreated or inadequately treated domestic wastewater has adversely affected the aquatic environment and public health in many cities in Vietnam. A conventional anaerobic–anoxic–oxic (AAO) process is recognized as an easy-to-handle approach that constrains chemical use during the procedure. Herein, we improve an AAO system by adding more oxic orders in association with a biological membrane in order to increase the hydraulic retention time (HRT) of the oxic zone in the system. The investigated system was applied to the treatment of real domestic wastewater during 168 days of operation. The performance of the system reached a stable state after 60 days of operation. The removal efficiency of total nitrogen (TN), total phosphorus (TP), total suspended solids (TSS), biological oxygen demand (BOD5), and chemical oxygen demand (COD) was found to be 93.6 ± 3.0%, 91.9 ± 3.5%, 88.6 ± 1.2%, 82.6 ± 1.4%, and 71.8 ± 0.7%, respectively. After the operation process, the TN, TP, and TSS contents in the wastewater effluents met the A level in accordance with the QCVN 14-MT:2015/BTNMT regulation, and the effluents of COD and BOD5 almost satisfied the requirement, with only some points being slightly higher than the limit values. The obtained data revealed that the AAO/O system was capable of treating domestic wastewater in small and medium-sized domestic wastewater treatment facilities.

Assessment of two sludge stabilization methods in a wastewater treatment plant in Sotaquirá, Colombia

Wastewater sludge is a by-product of waste water treatment; it is often employed in agricultural processes following appropriate microbiological stabilization. In this study, we evaluated two methods of sludge stabilization in the waste water treatment plant of Sotaquirá, Colombia. The two assessed stabilization methods were dewatering on drying beds and alkaline stabilization. The stabilization through dewatering on drying bed was carried out for five months. Alkaline stabilization was conducted for 96 hours with three concentrations of calcium oxide, 7%, 9%, and 13% w/w. Humidity, pH, organic carbon, phosphorus, organic nitrogen, fecal coliforms, somatic phages, total helminth eggs, and Salmonella sp. were monitored monthly for the sludge under dewatering treatment and at 0, 12, 24 hours for sludge under alkaline stabilization treatment. Both treatments succeded in eliminating Salmonella sp. Helminth eggs were eliminated by alkaline stabilization, whereas it was reduced to one or zero helminth eggs with the dewatering treatment. Somatic phages were eliminated with alkaline stabilization but were only reduced to 3.52 log CFU/g with the dewatering method. Dewatering on drying beds produced biosolids that can be used for soil restoration. Whereas alkaline stabilization produced biosolids that can be used for agricultural purposes. Alkaline stabilization with 9% and 13 % calcium oxide ostensibly reduced nitrogen and phosphorus contents in the sludge, whereas 7 % calcium affected less the phosphorus concentration of the sludge. These results indicate that sludge dewatering on drying beds is an effective sludge sanitation protocol to be implemented in small waste water treatment plants, such that in Sotaquirá, Colombia.

Evaluation of operation and management of Luocheng small municipal wastewater treatment plant

Operation efficiency, effect and operation energy consumption are the main basis for the evaluation of the operation and management level of wastewater treatment plant. The statistics of the operation data of the small municipal wastewater treatment plant in Luocheng County show that the operation rate of the facility is high, and the treated effluent reaches the Level A standard of the “Discharge standard of pollutants for municipal wastewater treatment plant” (GB18918-2002), and the various evaluation indicators of the urban wastewater treatment plant basically normal. However, the average operating load of some municipal wastewater treatment plant has not reached the index requirement for the operation period of production, and the load rates of CODCr and NH4+-N are mostly below 60%, and wastewater treatment plant unit wastewater volume, unit CODCr and NH4+-N load energy consumption is high. The reason is that the water quality of the design of the micro-municipal wastewater treatment plant is not reasonable, the construction scale is too large, and the operation fails to adopt effective management and control technology measures.

Study of Sequencing Batch Reactor operation with an inflow of wastewater with low concentration of organic contaminations

The paper is devoted to the study of small wastewatertreatment plants, in particular the study of wastewater treatment processes with the wastewater with low concentration of organic contaminations entering treatment plants. The primary goal of the study is to select the reactor operation mode to ensure the deep biological treatment quality of treated wastewater. The three-step experiment has been conducted in a licensed laboratory using high quality equipment. The results of the experiment and the analysis of the data obtained are presented.

Analysis of COD Fractions in Raw Wastewater Flowing into Small and Large Wastewater Treatment Plants

Analysis of COD Fractions in Raw Wastewater Flowing into Small and Large Wastewater Treatment Plants

Pollution and Sustainability Indices for Small and Medium Wastewater Treatment Plants in the Southwest of Spain

Two indices have been defined in this work to measure the pollution load that a Wastewater Treatment Plant (WWTP) receives and the efficiency of the process it carries out from the overall perspective of pollution removal and energy efficiency. The aim is to provide two performance parameters which could be used to characterize both the working conditions of a WWTP and how well it treats the pollution it receives. In this way, they may be used to compare the behavior of different plants in a certain geographical area. Forty-five WWTPs in the Southwest of Spain were studied to find out the most significant information that is to be used to identify and define both indices. Seven of the variables recorded were used to define each one. Their values were calculated for the whole set of plants studied. The results showed that most of the plants received a low pollution load. Only six of them suffered from a high pollution load, probably because of farms and food industries located in their surroundings. Only three plants showed a poor efficiency, while 23 of them presented a very good one.

Small sewage wastewater treatment plants for domestic wastewater

Small sewage wastewater treatment plants are used for treatment of domestic wastewater from individual residential houses, small schools, roadside cafes, restaurants, small railway stations, camping sites, etc., where there is no centralized sewage network. In cases when there is a limited space for the installation of small-scale treatment facilities, authors suggest using of septic tanks and drainage wells. Sewage effluents are collected with gravity force, without using electricity. Usage of proposed constructions does not cause pollution of soils and underground water horizons. Sanitary environment is stable and predictable.

Bioreactor for wastewater treatment

The article touches upon the efficiency of small capacity wastewater treatment plant for industrial sewage. Current operation scheme fails to meet existing regulation requirements due to several drawbacks. The article describes a technology for wastewater treatment and the construction of bioreactor to implement the scheme above. The technology includes averaging tank with preliminary mechanical treatment and bioreactor with floating feed. This provides the efficiency of removal of organic compounds and nutrients: BOD - 96%, nitrogen - 99%, phosphorus - 89%.

농촌 지역에서 유입 유량이 소규모 하수처리장 처리 효율에 미치는 영향

농촌 지역에서 유입 유량이 소규모 하수처리장 처리 효율에 미치는 영향

Tolerance to Ammonia of Thulinius ruffoi (Bertolani, 1981), a Tardigrade Isolated from a Sewage Treatment Plant.

The acute toxicity of ammonia on Thulinius ruffoi (Bertolani, 1981), a eutardigrade isolated from a small waste water treatment plant (WWTP) in Poland, was estimated. Our results show that no active individuals survived a 24 h exposure to solutions equal to or higher than 125 mg/L of total ammonia nitrogen (NH3–N + NH4+–N), which, under the conditions in our experiment, was equivalent to 1.17 mg/L of un-ionised ammonia (NH3). The LC50 concentration of total ammonia nitrogen was equal to 52 mg/L (or 0.65 mg/L un-ionised ammonia). Given that the norms for the concentration of ammonia in treated waters leaving WWTPs are usually several times lower than the LC50 for T. ruffoi, this species does not seem to be a good bioindicator candidate for WWTPs. In this paper we also note that various ecotoxicological studies use different methodological approaches and we suggest that a more uniform methodology may aid interspecific comparisons of LC50 values.

Research on Operation Mechanism and Application in Engineering of UNITANK Process

UNITANK is a new wastewater treatment technology combining the advantages of Sequencing Batch Reactor, normal aeration tank and 3-ditch oxidation treatment systems. It has been considered as an attractive pathway to be applied in small or middle wastewater treatment plants. It was chosen as the main process in Xingtai Wastewater Treatment Plant, Hebei Province, PR China. In this paper, the operation process, operation mechanism and features of UNITANK process were discussed in detail on the basis of the basic structure and the application in engineering.

Small domestic wastewater treatment using waste materials

Phosphorus pollution of groundwater from small wastewater system is often considered as a major threat for aquatic habitats. Recirculating biofilters are often used to treat small wastewater systems without significant removal of phosphorus. In this paper, a low-cost waste material (dried alum residual) in pre-treated effluents from recirculating biofilters was examined. Two different types of wastewater were used; one collected from a pilot scale biofilter from a municipality and the other generated in the laboratory using bench scale biofilter. Sorption-based treatment system was used to remove phosphorus using alum residual. Batch and fixed bed column tests were conducted. Results indicated that alum residual was effective in removing phosphorus. The presence of organic matter (BOD5) showed to have decreased the phosphorus sorption behaviour. The leaching of aluminium was reasonable and in many cases aluminium was adsorbed onto the alum residual.

Design and Efficiency of a Domestic Sewage Treatment System with Microorganism-membrane on Island Based on Entropy Theory

Domestic sewage treatment by water drainage network plus septic tank is not suitable on very small islands because of traffic and urban infrastructure problem. This study deals with a microorganism-membrane domestic sewage treatment system on small islands, which can degrade and clean the domestic sewage locally by effective microorganism and membrane system and makes the emission in market. Eight kinds of commercial complex microorganisms decompose powder were chosen to analysis the activities of protease, lipase, cellulose and amylase. And relating model based on entropy theory was constructed to evaluate the effect of enzyme activity, then the best commercial complex microorganism decompose powder was confirmed. The designed microorganism- membrane wastewater treatment system was applied to treat domestic sewage on a small island. The results showed that the removal rate of organic matters including the five-day Biological Oxygen Demand (BOD5), Chemical Oxygen Demand (COD) and ammonia nitrogen (NH 3-N) reached more than 98%. The removal rate of Total Dissolved Salts (TDS) of the outlet water was higher than 99%. This system was especially suitable for small islands domestic wastewater treatment.

Research on UNITANK Technology and its Application in Municipal Wastewater Treatment Plant

Land treatment process was chosen as the first-stage project in Xingtai Wastewater Treatment Plant located in Xingtai city, Hebei Province, PR China. UNITANK was chosen as the treatment technology in the secondary project in order to ameliorate the drawbacks of large land occupation and inconvenient management. In this paper, the operation modes of sewage treatment system, flush water system and sludge discharging system of UNITANK were discussed in detail on the basis of introduction of the basic structure and the technological process. According to the analysis of the project, it is suggested that UNITANK is more suitable for small or middle wastewater treatment plants with the advantages of simple structure, less land occupation, cost-efficient and reliable operation.

Reduction of Organic Sludge using High Efficiency Aeration System(HEAS)

In Korea, ocean dumping has been widely used as the ultimate disposal of sewage sludge. However, ocean dumping of food wasted and sewage sludge from 2013 is expected to legally restricted as London convention on marine pollution prevention has been effective in 2009. This research aims to examine the effect of HEAS in treating the environmental pollution load caused by organic high concentrated sludge. Thus, onsite laboratory scale treatability test using HEAS was adopted to treat the high concentrated organic sludge from sewage and industrial wastewater treatment plant. The research results showed that the HEAS is useful to reduce the environmental pollution caused by organic high concentrated sludge. Specific results are as follows. 1. The organic removal after the sludge digestion using the high efficiency aeration system was 55.2-85.8%. Although these results were lower than those from the general sewage treatment, the high efficiency aeration system could be evaluated as efficient, considering the object sludge contained the industrial waster water. 2. The average removal efficiency was about 25.2%. 3. It was revealed that sludge digestion by the high efficiency aeration system could effectively contribute to the sludge treatment cost. Especially, the high efficiency aeration system is more applicable to the onsite treatment of small sewage and wastewater treatment plant that contains high solid content sludge, industrial wastewater sludge, high fixed solid sludge.

Nitrogen Removal and Sustainability of Vertical Flow Constructed Wetlands for Small Scale Wastewater Treatment: Recommendations for Improvement

The goals of environmental sustainability, through minimizing resource use, maximizing energy efficiency, reducing waste emissions, enabling recycling, and increasing resilience are becoming primary in wastewater treatment, along with traditional goals of protecting human health and water quality. Sustainable designs, defined as design of human/industrial systems to ensure that use of natural resources and cycles do not lead to diminished quality of life due to losses in future economic opportunities or to adverse impacts on social conditions, human health, and the environment (Mihelcic et al., 2003) are needed to provide or replace sanitation policy and technology to meet increasing demands. The challenge for wastewater professionals is to design and operate treatment processes which are environmentally sensitive throughout the life-cycle and support human well being. This research focused on one technology for small-scale wastewater treatment: the vertical flow constructed wetland (VFCW), which was investigated for the capacity to remove ammonium and nitrate nitrogen from wastewater. This title belongs to WERF Research Report Series . ISBN: 9781843395324 (eBook)

Treatment of Wastewater Phosphate by Reductive Dissolution of Iron: Use of Ferric Oxyhydroxide Media

In smaller wastewater treatment systems such as septic systems, there is an interest in the development of passive phosphorus (P) removal methods. This study tested fixed-bed filters containing ferric oxyhydroxide media for wastewater P removal in a laboratory column test and in a full-scale domestic septic system. In the column test, during 30 mo of dosing with domestic wastewater, reductive iron dissolution reactions delivered consistent moderate concentrations of Fe into solution (2.9 ± 1.6 mg L), and influent PO-P of 3.7 ± 1.0 mg L was attenuated to 0.09 + 0.04 mg L in the column effluent (98% removal). Phosphorus breakthrough at successive locations along the column indicated that in addition to sorption, mineral precipitation reactions probably also played an important role in the observed P attenuation. This was supported by electron microprobe analyses, which showed the presence of thick (20 μm) secondary Fe-rich coatings containing P on the primary ferric media grains. Assays of NaHCO-leachable and acid-extractable P on the column solids showed accumulation of up to 5.4 mg g acid-extractable P near the column inlet, but <5% of this amount was easily desorbable, further indicating P attenuation from processes other than sorption. Over 19 mo of operation, the domestic septic system also showed generally consistent increased Fe in the filter effluent (2.6 ± 1.7 mg L) and achieved 99% P removal to 0.03 ± 0.02 mg L when the effluent was subsequently oxidized in a sand filter. Ferric iron filters could be attractive options for P removal in smaller wastewater systems because of their passive nature.

Processing of sewage sludge: Dependence of sludge dewatering efficiency on amount of flocculant

Paper presents results of experimental dewatering of stabilized sludge analysis and study. The experiments were carried out at a small waste water treatment plant (15,000 population equivalent). Experiment focused on impact of consumption of flocculant and centrifuge load on quality of dewatered sludge and centrate. Dry solids in dewatered sludge and content of undissolved particles in the centrate were observed in particular for proper evaluation of the experiment. It was proven that specific consumption of flocculant has greater impact on centrate quality than on dry solids content in dewatered sludge. It was possible to increase dry solids content in dewatered sludge only by 10% at most. However, amount of undissolved particles dropped more than ten-fold. Regarding quality of dewatered sludge and centrate, optimum specific consumption of flocculant during the experiment amounts to 8 g/kg of dry solids of sludge with flocculant concentration being 0.16% and centrifuge load reaching 110 kg/h of dry solids. Specific consumption of flocculant amounting to 5.4 g/kg of dry solids of sludge (calculated value) under identical operational conditions proves to be the best economical option.

Distribution of heterotrophic and autotrophic organisms in a biological aerated filter

Biological aerated filtration is a viable option for small municipal wastewater treatment plants. A low cost filter media was obtained by triturating volcanic rock. An apparent porosity of 46 % and a specific surface area of 395 m2/m3·d were obtained once the filter was packed by using a grain size of 8.2 mm. The performance of the system, operated as a biological filter, was evaluated under an average organic load of 2.6±0.4 kgCODT/m3·d (6.7±1.1 gCODT/m2·d) without primary and secondary settling. The average CODT decreased from 220 mg/l in the influent to 88 mg/l in the effluent and the CODD was decreased from 148 mg/l in the influent to 50 mg/l in the effluent. The filter media, in combination with the biofilm, allowed a 75 % TSS removal. The ammonia nitrogen decreased from 51 mg/l in the influent to 33 mg/l in the effluent. The maximum flux coefficients of 9.3gCODdissolved/m2·d and 2.9gNH4-N/m2·d at the biofilm surface were used to simulate, with the Michaelis-Menten model, the profiles of dissolved COD, ammonium and nitrates through the aerated filter. It was possible to conclude that the backwashing procedure removed the excess biomass and was responsible for a homogeneous distribution of heterotrophic and autotrophic microorganisms along the filter depth.

Failure and Subsequent Restoration of EBPR Capability of a Small Community Wastewater Treatment Plant

Failure and Subsequent Restoration of EBPR Capability of a Small Community Wastewater Treatment Plant