The Innovation of Tofu Waste Liquid Biogas Reactor Technology as an Alternative Energy Resource

The tofu industry is growing rapidly, along with the increasing number of people in Indonesia. On the other hand, industrial liquid waste contains very high organic compound that potentially pollutes the environment. Without a good handling process, tofu liquid waste can cause a variety of negative impacts such as water pollution, unpleasant odor, and lower aesthetic to the environment. Most tofu industries are run by small and medium industries so that the disposal of its waste is less attention. Liquid waste from the tofu industry can be used to produce biogas through an anaerobic process if it is well processed. The aim of this research is to measure the physical and chemical parameters of liquid waste in one of the tofu industries in Bantaeng by taking samples at three different points. Based on the physical parameters obtained temperature, TDS, TSS, smell and color from three points for Point I are 29.6°C, 1932 mg/L, 7690 mg/L, smelly and white-colored, point II are 27.8°C, 540 mg/L, 1646 mg/L, smelled, murky-colored, point III temperature of 29°C, 510 mg/L, 288 mg/L. Based on chemical parameters, the tofu liquid waste pH, BOD (Biochemical Oxygen Demand), and COD (Chemical Oxygen Demand) for the point I, II, and III in a row are pH (7-7.8); BOD 7.5 mg/L, 3.3 mg/L, 9.6 mg/L; COD 1405 mg/L, 930 mg/L, 370 mg/L. From the parameters that have been measured. It be can be concluded that some parameters for industrial tofu liquid waste is still unqualified to the requirements of the quality standards set by KEPMENLH No. 5 in 2014. The unqualified standards are the TSS parameter and COD so that further research is required in order for the industrial liquid waste can be disposed of to the environment.

Liquid waste is a significant problem in environmental control. Waste discharged into water bodies will inevitably pollute the surrounding water body, disrupting the life of living organisms nearby. The tofu industry on Jalan Bangka VII Pela Mampang, Mampang Prapatan Subdistrict, South Jakarta, produces liquid waste collected in waste tanks and discharged directly into water bodies without prior treatment. This causes visible turbidity in the water bodies and foul odors from the tofu industry’s liquid waste, which can disturb nearby residents aesthetically and due to the potential emergence of diseases. Tofu liquid waste can be treated biologically or chemically. Anaerobic biological treatment can be about 70% efficient. This research aims to determine how to treat liquid waste in the tofu industry using a plug-flow reactor. The biogas production methodology involves three stages. Stage I involves preparing a set of biogas digesters. Stage II involves mixing tofu liquid waste and EM4 in a 1:1 weight ratio and placing it in the digester, followed by analyzing the raw materials, including COD, BOD, pH, and acetic acid analysis. Stage III involves a continuous fermentation process in the digester for 60 days with variables including HRT (Hydraulic Retention Time) of 30, 20, and 10 days of operation and temperature control to keep the fermentation conditions constant at 30°C. Therefore, appropriate and effective HRT and OLR (Organic Loading Rate) are needed to produce biogas from tofu liquid waste. In this study, the researcher will use a digester for 60 days to produce biogas from the tofu factory’s liquid waste.

This research is intended to analyze the quality of tofu liquid waste, analyze the quality of river water around the tofu industry in Mejing Village and analyze government policies in managing tofu liquid waste. The research method used is grab sampling, observation, and interviews to obtain primary data. Secondary data from journal articles and research reports are used to support primary data. The research results show that the quality of tofu liquid waste has a pH of 2.8-33, a temperature of 41-51 oC and is not in accordance with established quality standards. Tofu liquid waste also has a pungent sour odor, yellowish color, and contains many suspended particles. Disposal of tofu liquid waste into the waters causes the river flowing in Mejing Village to be dirty and indicates light to heavy pollution. The government has set quality standards for wastewater produced by the tofu industry. Unfortunately, the tofu industry in Mejing Village does not comply with this regulation properly. The low awareness of tofu industry players to manage liquid waste is caused by various factors. Good communication between the government and industry players is needed so that industry players know how to process the liquid waste they produce. The government needs to supervise the application of government regulations related to the management of tofu liquid waste and provide sanctions to industries that violate it. Planning for a communal IPAL as well as an appropriate solution must be realized immediately so that the problem of tofu liquid waste in the tofu industry center in Mejing Village can be resolved immediately.

Tofu Industry is a company that produces liquid waste that has the potential to pollute the environment and is one of the industries that produces organic waste. The presence of organic elements in tofu liquid waste causes researchers to use tofu liquid waste into liquid organic fertilizer that has added value. This liquid organic fertilizer can be an alternative at a low price compared to other liquid organic fertilizers on the market. This liquid organic fertilizer is manufactured mainly from tofu liquid waste with coconut water, brown sugar solution, and EM4 solution. The method of making liquid organic fertilizer is a random design complete with three treatments. Each sample composition is 1 liter of liquid waste, 2 liters of liquid waste, and 3 liters of liquid waste. The laboratory test results show that in liquid organic fertilizer, N, P, and K show that treatment A has the best results with N values of 0.42%, P 0.13%, and K 0.29%. The results of the techno-economic analysis are that the cost of goods produced is obtained at Rp. 5,178.75 / liter, the break-even point of 95.58 liters, and it takes 42 days to break even. The payback period only takes 0.9 years. For further research, the process of making liquid organic fertilizer should produce samples on a large scale to minimize the calculation of techno-economic analysis in the direct labor wage section.

Tofu is a food that every level of society liked because of its low price and many nutrient contents. Tofu making uses a lot of water for sorting, immersion, boiling, and filtering to produce enough liquid tofu waste. The problem that most rises related to the tofu industry is the problem of waste processing. If the tofu waste is disposed of directly into the river, it will affect the life of biota and pollute the environment. Therefore facility is needed for wastewater treatment that can be used continuously with a wetland construction system. The A filter composition consists of sand, charcoal, and zeolite. The B composition consists of soil, palm fiber, sand, charcoal, and zeolite with cattail plants (Thypa latifolia). C composition consists of soil, palm fiber, sand, charcoal, and zeolite with cattail plant (Thypa latifolia) and Phragmites australis. The three compositions are then analyzed in filtering the tofu industrial wastewater. The best result of tofu liquid waste processing is using the C wetland composition construction; pH with a value of 6.7 BOD with a value of 146mg/L, COD 338mg/L, TSS 123mg/L.

Environmental pollution by human activities is often found in the environment around residences that live close to industry in both the formal and informal sectors, one of which is the tofu factory. Gedanganak Village is one of the sub-districts located in West Ungaran sub-district, Semarang Regency. Gedanganak sub-district consists of several hamlets, where the residents make their living as laborers and tofu craftsmen. People who do not know how to use liquid waste from tofu factories can be overcome by providing information, education and training to process liquid waste from tofu factories into organic fertilizer to achieve food security and increase people's income in Gedanganak Village. There is a need for liquid waste processing in the tofu industry. One innovation that can be done to reduce tofu waste is by using it into Tofu Go Green products. The purpose of this empowerment is to provide empowerment regarding the use of tofu liquid waste into organic fertilizer in the Gedanganak Village Community. The methods used are education, training and demonstration The result of Community Empowerment with training in making organic fertilizer from tofu liquid waste is that the community is able to independently utilize tofu liquid waste which has not previously been utilized. ABSTRAK Pencemaran lingkungan oleh aktivitas manusia kerap ditemui dilingkungan sekitar tempat tinggal yang bermukim dekat dengan industri baik sektor formal dan informal, sektor informal salah satunya adalah pabrik tahu. Kelurahan Gedanganak merupakan salah satu kelurahan yang terletak di kecamatan Ungaran Barat Kabupaten Semarang. Kelurahan Gedanganak terdiri dari beberapa dusun, dimana penduduknya bermata pencarian sebagai buruh dan pengrajin tahu. Masyarakat yang tidak mengetahui bagaimana pemanfaatan limbah cair pabrik tahu dapat diatasi dengan memberikan informasi,edukasi, dan pelatihan mengolah limbah cair pabrik tahu menjadi pupuk organik untuk mewujudkan ketahanan pangan dan menambah penghasilan masyarakat di Kelurahan Gedanganak. diperlukannya pengolahan limbah cair pada industi tahu tersebut, salah satu inovasi yang dapat dilakukan untuk mengurangi limbah tahu tersebut yaitu dengan memanfaatkannya menjadi produk Tofu Go Green. Tujuan dari pemberdayaan ini adalah untuk memberikan empowerment mengenai pemanfaatan limbah cair tahu menjadi pupuk organik pada Masyarakat Kelurahan Gedanganak. Metode yang digunakan adalah edukasi, pelatihan dan demonstrasi. Hasil dari Pemberdayaan Masyarakat dengan pelatihan pembuatan pupuk organik dari limbah cair tahu yaitu masyarakat mampu mandiri untuk memanfaatkan limbah cair tahu yang sebelumnya belum dimanfaatkan.

From the tofu production process. The waste generated by tofu industries can be divided into two types, i.e the solid waste and liquid waste. One effort to reduce the environmental damage due to tofu liquid waste from the processing of tofu is to make the tofu liquid waste into biogas. The effort to convert liquid waste from tofu factories into biogas reguires a biogas reactor. The aim of this study was to design a biogas reactor with a size of 1 m 3 (1000 Liters) by using materials and equipment that are very easily available in the market at an affordable price, to determine the pressure, pH value and the quality of the flame produced when the biogas is used as fuel gas stove. The method used in this study is an experimental method within 30 days. The results showed that biogas pressure increased with increasing time (days). Maximum pressure is reached on day 21, which is 12.2 kPa. The average pH value is 6.91. The temperature in the biogas reactor tends to be stable with an average temperature of 31 o C. The color of the flame when the biogas from tofu liquid waste is used as a gas fuel for a large flame gas stove is still a mixture of blue and yellow. The utilization of tofu liquid waste into biogas is expected to reduce environmental pollution and make tofu liquid waste become a high economic value and environmentally friendly.

A natural feed of freshwater fish as long as it depends on worms tubifex is hard to be cultivated. Daphnia sp is one of the kinds of Cladocera zooplankton to be an alternative as a natural feed for seed of fish. The liquid tofu waste generally is a problem that is going on in every regional particularly around the Kedu Residency, Central Java. The liquid waste has the nutritional value that can be used for cultivation Daphnia sp. The right concentration of liquid waste tofu to the cultivation of Daphnia sp. has not been studied. This research aimed to find out the influence of concentration out over the density of waste biomass and the visibility of morphology Daphnia sp. The experiment used Complete Randomized Design (CRD) with three treatments and three repetitions, 25:75, 50:50, dan 75:100 (TI, T2, and T3, respectively), tofu liquid waste and water. The results concluded that T3 has repercussions for the density and biomass Daphnia sp. The density of Daphnia sp. was shown by treating 75 % of liquid tofu waste with 31.33 ind L-1 on average and while biomass was 4.6 g L-1 on average. The visibility of Daphnia sp morphology was cultivated with liquid tofu waste compared with Daphnia sp. cultivated using wastewater of catfish cultivation as a control group.Keywords: Biomass, Daphnia sp., Liquid tofu waste, Present of morphology

The increase in population from year to year causes an increase in the need for food such as Tofu. This also has an impact on the number of tofu industries in Indonesia. The tofu industry is a food industry that is in great demand by the public, raw materials are easy to find, and processing is easy. Nevertheless, it arises that the environmental problems posed by the tofu industry are waste generated from the liquid tofu waste manufacturing process. When discharged into the environment, it can cause a foul odour and pollute the environment. The utilization of tofu liquid waste into electrical resources is one of the steps that can be developed in reducing pollution and increasing electrification. Being the first step, it is necessary to study the use of biomass as a source of electricity, which includes studying the potential of resources. This study aims to determine the potential value of tofu liquid waste and electrical energy for PLTBG fuel as an effort to apply clean technology. For the method in this study using anaerobic fermentation with SuperPro Designer simulation. As a result of this study, tofu liquid waste produces methane gas (CH4) of 141.97 m3 per day and total electrical energy of 129.03 kWh. It can be concluded from this study, tofu liquid waste can be used as biogas for generator set fuel with an output power of 12,000 Watts which meets industrial electricity needs for 11.73 hours.

The tofu processing industry in Indonesia is massively increasing. The increasing activity of tofu production causes the disposal of tofu industrial waste to the environment to be higher as well. This condition is exacerbated by the fact that generally, the tofu industry producers do not have their appropriate tofu waste management system. The liquid waste generated from the tofu processing industry will be discharged directly into the waterways. Additionally, people in Indonesia generally use rice as their staple food. The rice washing process produces washing wastewater which is usually discharged into the environment directly. The disposal of these wastes raises the environmental pollution rate. Also, the tofu liquid waste and rice washing water contain some nutrients such as proteins, fats, carbohydrates, and vitamins. The presence of these nutrients will increase the population of pathogenic microbes in the environment. Thus, in this study, the authors discussed the potential of tofu wastewater and rice washing wastewater as alternative media for the growth of Trichoderma sp. Trichoderma sp. is an antagonistic fungus that can be used as a biocontrol agent for farmers. The use of waste as an alternative medium reduces the mass production and propagation cost of biological agents. In this study, this isolate was cultivated in tofu liquid waste and rice washing wastewater by adding a carbon source. Based on the research conducted, it was known that the average conidial density of Trichoderma sp. cultivated in tofu liquid waste was 2.9 x 106, while the conidial density of Trichoderma sp. cultivated in alternative rice washing wastewater was only 1.6 x 106. The growth of this isolate in tofu liquid waste was higher than rice washing water. It indicated that tofu liquid waste potentially to be used as a cheap alternative growth medium for Trichoderma sp.

<div class="WordSection1"><p><em>Tofu liquid waste can be further processed to produce some useful product. That can be kept anaerobically to produce some organic acid</em><em>. </em><em>The purpose of this study to know the microbial growth behavior characteristic of liquid tofu waste which produce with different production process, such as specific growth rate (</em><em>m</em><em>), doubling time (td), multiplication degree (n), product yield, and efficiency of acetic acid production. This study is also aimed to identify the acid type which produce with different production tofu process. The liquid waste which used for this study is obtained from tofu producer which uses acetic acid and calcium sulfate to coagulate the tofu protein</em><em>. </em><em>Liquid tofu waste was incubated 24 hour, in ambient temperature(30<sup>o</sup>C). analysis of total cell count, glucose concentration, acetic acid concentration, and pH value was evaluated in certain interval, such 0, 2, 4, 6 8, 10, 12, 14 16, 18, 20, 22, 24 hour. Acid type identification was evaluated in some phase during fermentation process. The observation result was plotted into a graphic which was shown the relationship of total cell count, with glucose concentration, acetic acid concentration, and also fermentation time.</em><em> </em><em>From the analysis of observation result, It can be concluded that, the specific growth rate of liquid tofu waste with acetic acid as protein coagulator is 0,3015/hour, while the specific growth rate of liquid tofu waste with calcium sulfate as protein coagulator is 0,2174/hour. The doubling time of liquid tofu waste with acetic acid as protein coagulator are 2,2991 hours, while the doubling time of liquid tofu waste with calcium sulfate as protein coagulator are 3,1877 hours. The multiplication degree of liquid tofu waste with acetic acid as protein coagulator are 2,605 times, while the multiplication degree of liquid tofu waste with calcium sulfate as protein coagulator are 1,880 times. The growth yield constant (Y p/s) of liquid tofu waste with acetic acid and calcium sulfate as protein coagulator respectively 8,1 x 10<sup>9 </sup>cfu/mg and 8,1 x 10<sup>7</sup> cfu/mg. The product yield constant (Y p/s) of liquid tofu waste with acetic acid and calcium sulfate as protein coagulator respectively 1,7237 and 0,0306. The efficiency of acetic acid production during fermentation of liquid tofu waste with acetic acid and calcium sulfate as protein coagulator respectively 15,1376% and 2,5699%. Acid type identification shows that acid which was contained in liquid tofu waste recognized as Acetic acid.</em></p></div>

The tofu industry during the processing produces waste in both in liquid and solid forms. Solid waste is usually used as animal feed, fertilizer, tempe or crackers. Liquid waste is used as nata de soya, paper, bioplastics, biogas, electrical energy and organic fertilizers. Small-scale tofu industry rarely utilizes tofu liquid waste and some do not carry out processing. Tofu waste contains organic substances and high suspended solids that can pollute the environment. Therefore, there is a need for waste treatment using an aerobic biofilter. The operating Hydraulic retention time was 5, 10 and 15 hours, the filter height was 135 cm and the nipah fiber height was 50 cm. The results of the biofilm attached to the biofilter reactor and palm fiber were successfully formed a brownish red biofilm which is a colony of microorganisms. The optimum time of tofu liquid waste showed a residence time of 15 hours, so that tofu liquid waste meets the quality standards based on the Regulation of the Minister of the Environment of the Republic of Indonesian No.5 of 2014. The effectiveness of the biofilter reactor in reducing COD is 94.24%, BOD is 95.14% and TSS is 68%.

Liquid waste produced from tofu industry which is containing suspended and dissolved solids will physically, chemically and biologically change. The poisonous substance yielded from the change is potential to disturb human health. The preliminary study showed that the measurement of H2S concentration in Tofu Industry “X” in its liquid waste was 0,394 mg/l or exceeding the standard threshold. One of the methods to reduce the gas is by adding wood vinegar. The study was an experiment with post test only with control group design. The amount of liquid waste sample used was 20 liter and there were three dose variations of wood vinegar observed, i.e. 5 ml, 10 ml and 15 ml for every 1000 ml liquid waste. Based on the result of One Way Anova test at 95 % level of confidence, the p-value obtained was < 0,001, which means that the various doses of wood vinegar had different effects in decreasing H2S level in tofu liquid waste. The subsequent LSD test showed that the highest mean difference with the control group was reached by Dose C (15 ml wood vinegar in 1000 ml liquid waste). However, Dose B (10 ml) was already able to fulfill the permitted threshold of 0,1 mg/l.

Tofu liquid-waste is a kind of organic waste that may cause pollution to the environment especially in soil and water. In order to reduce the pollution caused by tofu liquid waste, the photo-degradation of tofu waste is becoming one of promising method because of its low cost and low energy consumption. The graphitic carbon nitride (g-C3N4) is known to have an ability of organic waste degradation with the aid of visible light. In this research, the photo-reduction of the liquid waste from tofu industry was done by various prepared g-C3N4 photo-catalysts and various liquid waste conditions. The experimental result shows that the catalyst is confirmed to have ability to reduce both the COD and BOD of tofu liquid waste. The optimum degradation result of tofu liquid waste was obtained by photo-catalytic process using photo-catalyst g-C3N4 prepared by 10M HCl concentrations, and pH 3 of the liquid waste.

Biomass is valuable alternative energy worldwide as a substitute for fossil fuels can be converted into various forms of usable energy such as heat, steam, electricity, biogas, and liquid transportation biofuels. Cabbage waste, tofu liquid waste, cow dung and chicken manure is dangerous for the surrounding environment, which produces CH4 gas and has quite high BOD and COD values. This liquid waste has an amount of COD, suspended solids, and a high total solids content. One solution to overcome this pollution is by processing the waste into biogas, especially methane gas. The material will be transformed into methane gas by fermentation through the anaerobic digestion method. Before converting into biogas, initial characterization will be carried out in total C content, total N, COD, and C/N ratio. Then, from the biogas produced, the maximum data obtained is in variable B4 (55% cow dung: 15% chicken manure: 15% cabbage waste: 15% liquid tofu waste) with a total amount of gas of 7140 ml. This shows that tofu liquid waste can increase the potential amount of biogas produced.