Continuous-series microbial fuel cell for tofu liquid waste: effects of catholyte and inoculum

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

<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 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.

Food waste and tofu liquid waste have great potential to be used as raw materials for organic liquid fertilizer. Food waste contains essential nutrients, such as nitrogen, phosphorus, and potassium, which plants need for optimal growth. Besides that, tofu liquid waste contains nutrients 1.24% N, 5.54% P2O5, 1.34% K2O, and 5.803% C-Organic which plants need so that tofu production wastewater potential to make organic fertilizer. The potential for tofu liquid waste and food waste around the Sardulo Seto youth group interested the PkM team in training on making organic liquid waste from food waste and tofu liquid waste. In this activity, several stages were carried out, namely (1) Training on Making Organic Liquid Fertilizer, (2) Assistance in the production of Liquid Organic Fertilizer, (3) Testing the Quality of Liquid Organic Fertilizer, and Testing the Growth of Chili Plants. The results show partners can improve partner understanding of utilizing waste and producing organic liquid fertilizer for food waste and tofu liquid waste very well. In addition, the results of the quality test of liquid fertilizer (PCT-14) showed pH 5, C-Organic contain 8.46%, N 4.71%, P2O5 5.78%, and K2O 2.13%. The results showed that chilies that had been treated with PCT-14 were taller than untreatted

Biopore infiltration hole are hole made for run-off flow which if allowed to cause erosion and can remove the topsoil, causing soil fertility to be reduced. The use of biopori infiltration holes can be maximized by adding organic matters into the hope that in addition to absorbing water it can increase soil fertility. The liquid waste of tofu and meranti litter is an organic matters are used in this study, by adding organic matters to the biopori hole. This study aims to look at the effect of providing organic matters in the biopore hole derived from tofu and litter liquid waste on the value of pH, C-Organic, and post-mining CEC. This study was an experimental study in the field using a completely randomized design of one factor, namely organic matters with six levels, namely without organic matters and using 25 g, 50 g, 75 g, and 100 gr organic matters given to the biopori hole in incubation for one month later Soil samples taken were analyzed for pH, C-organic, and CEC. The results showed that the treatment only affected the soil's pH value. Organic material provided in the biopori hole is thought to have not completely decomposed, causing the soil around the biopori infiltration hole to remain acidic. The acidity of the soil is due to the gases produced during the decomposition process. Changes in soil pH ranged from 4.36 to 4.65 by administering 75g of organic matters from tofu liquid waste and meranti litter. This research is useful in post-mining land reclamation in increasing soil fertility, with the improvement of soil chemical properties such as pH will slowly improve the physical and biological properties of the soil so that it can be used as cultivation land.

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.

The organic matter present in liquid waste is highly valuable due to its protein content, which ranges from 40 to 60 percent. The levels of Chemical Oxygen Demand (COD) in tofu liquid waste typically exceed the established quality threshold, necessitating proper management prior to its release into the environment. A method for treating liquid waste from tofu production involves combining filtration and phytoremediation utilizing apu wood (Pistia stratiotes L). The objective of this study is to assess the efficacy of filtration and phytoremediation techniques in lowering Chemical Oxygen Demand (COD) in tofu liquid waste. This study used a Pretest-posttest Control Group experimental research design. Population and Sample The subject of this study is the liquid waste generated by tofu business X in Banjarbaru. The treatment's effect was examined using One Way Analysis of Variance (ANOVA). The findings indicated that the use of the filtration and phytoremediation techniques using Apu wood (Pistia stratiotes L) effectively decreased the amounts of COD in tofu liquid waste. The most effective plant weight variation for reducing COD levels was 200 grams, resulting in a 67% reduction. Filtration techniques and phytoremediation have effectively decreased the levels of chemical oxygen demand (COD) in liquid waste from tofu production. Nevertheless, it still surpasses the quality criteria. Additional processing techniques can be implemented by future researchers to enhance the quality of tofu liquid waste prior to its release into the environment or water sources.

Propagation of B. thuringiensis in agricultural liquid waste media can be done because the waste still contains nutritional components which contain carbon and nitrogen. The aim of research was to study B. thuringiensis in a liquid formulation with high toxicity against Oryctes larvae. Parameters of observation were spore density, larval mortality and symptoms of both infection or death larvae. Experimental was designed as a completely randomized design with 6 treatments and 4 replications. Oryctes larvae used were 3rd-instar. The treatments were 1). Tofu liquid waste; 2) Tofu Liquid Waste + Bio-urine (1:2); 3) Tofu Liquid Waste + Bio-urine (1:1); 4) Tofu Liquid Waste + Bio-urine (2:1); 5) Bio-urine and 6) NB media (as control). The results showed the highest spore density was found in tofu liquid waste propagation media and biourine (1:2). The highest larval mortality was shown in treatment of Tofu Liquid Waste + Bio-urine (1:2), which was 91.67%. Observations on the symptoms of infection and death in tested larvae were indicated by changes in color of integument and fragility of the larva's body. Bio-insecticide with active ingredient of B. thuringiensis in liquid formulation has potency to be used as biological agent for controlling O. rhinoceros larvae.

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.

Biogas is a mixture of several gases produced from the process of overhauling organic materials by microorganisms in a state without air or anaerobically. This study aims to analyze the production and quality of biogas produced from tofu liquid waste with a mixture of cow dung. The study was conducted with 4 treatments, namely 80% liquid waste tofu and water + 20% cow dung (T80K20), 70% liquid waste tofu and water + 70% cow dung (T70K30), 60% liquid waste tofu and water + 40% dung cattle (T60K40), and 50% tofu liquid waste and water + 50% cow dung (T50K50). Each was replicated 3 times with data analysis using a completely randomized design (CRD). The highest methane gas production in the T50K50 treatment was 64,986.97 ml and the highest methane gas content in the T50K50 treatment was 43% in the sixth week. Keywords:Anaerob,Carbon dioxide,Methane,Gas production.

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.

In the planting program of lamtoro (Leucaena leucocephala), healthy and vigorous seedlings are needed, therefore, it is necessary to apply fertilizer at the nursery stage. The purpose of this study was to determine the effect of tofu's liquid waste and cow's urine on the growth of lamtoro seedlings at aged 6 weeks until 14 weeks. The treatments consisted of control, tofu’s liquid waste (30% and 40%), and cow’s urine (50%, 60% and 70%). Treatment was given every 2 weeks. Parameters observed were height, diameter, number of leaves, biomass, toughness, shoot root ratio, seedling quality index and chlorophyll content. The results showed that 30% and 40% of tofu’s liquid waste had a significant effect on increasing the height growth at 6 weeks and 8 weeks old seedling. The 70% cow’s urine has a significant effect on increasing the height growth at 6 weeks until 12 weeks old seedling. The 60% cow’s urine had a significant effect on increasing the number of leaves.

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.

Xylanase is an important enzyme for xylan degradation into xylan derivative compounds such as xylose, xylobiose, xylotriose and other oligoxylan. Xylan derivatives can be bioconverted into bioenergy (ethanol), food ingredients as well as pharmaceutical or nutraceutical goods. Some bacteria have been reported to produce xylanases using defferent kinds of agricultural wastes as a substrate. The objective of this experiment was to optimize the concentration of corn cobs as a carbon source and liquid tofu waste as nitrogen source on xylanase production by Bacillus subtilis AQ-1. A 2 2 central composite experimental design was performed to optimize the corn cobs and liquid tofu waste concentration. A second order quadratic model and a response surface method showed that the optimum condition for xylanase production was 1.1 % (w/v) corn cobs and 0.00198 % (v/v) total N of liquid tofu waste with the highest xylanase production of 122.99 U/ml. Key words: bacillus subtilis AQ-1, xylanase, corn cob, liquid tofu waste

Limbah cair tahu mengandung gas-gas yang terdekomposisi bahan-bahan organik yang terdapat di dalam air buangan seperti gas nitrogen (N2), oksigen (O2), hidrogen sulfida (H2S), ammonia (NH3), karbondioksida (CO2) dan metana (CH4). Penelitian sebelumnya menemukan bahwa kandungan ammonia pada limbah cair tahu berkisar antara 21,4 mg/L hingga 33,5 mg/L. Angka ini sangatlah tinggi jika dibandingkan dengan standar yang sudah ditetapkan oleh pemerintah yaitu sebesar 8 mg/L. Tujuan dari penelitian ini adalah untuk mengurangi pencemaran lingkungan yang disebabkan oleh ammonia yang berasal dari limbah cair tahu dan mengoptimalkan pemanfaatan limbah cangkang kelapa sawit. Pengurangan kadar ammonia ini dilakukan dengan metode adsorbsi, sedangkan metode analisis kadar ammonia menggunakan spektrofotometri. Arang aktif cangkang kelapa sawit diaktivasi menggunakan larutan H2SO4. Variasi waktu kontak yang digunakan adalah 30, 60, 90 dan 120 menit, sedangkan variasi massa adsorben adalah 2, 4, 6 dan 8gram. Hasil penelitian menunjukkan kondisi optimal untuk proses adsorpsi ammonia adalah 30 menit waktu kontak dengan 4gram jumlah arang aktif. Hasil karakterisasi menunjukkan bahwa arang aktif memenuhi standar kualitas dan cocok untuk mengurangi kadar ammonia dalam limbah cair tahu. Hasil penelitian ini dapat diaplikasikan untuk pemanfaatan limbah cangkang kelapa sawit untuk penurunan konsentrasi ammonia pada limbah cair tahu.