TECHNOLOGY FOCUS - BIOLOGY - Preferred Method: The method involves (a) passing the manure produced by livestock to underground sewer, precipitating the livestock manure, subjecting the precipitate to solid-liquid separation and separating solid portion and liquid portion using submersible pump, (b) processing the solid portion using screening machine to obtain organic fertilizer used for pasture and crop cultivation by (i) passing the portion of the resulting wastewater into sewage pipe network, again passing the sewage to second well and obtaining precipitate, and (ii) composting and fermenting the precipitate, crushing the mixture, screening and processing organic fertilizer and handling the processed materials, (c) performing anaerobic fermentation of the liquid portion formed in the sewage treatment system, obtaining biogas slurry and processing the biogas slurry to obtain organic fertilizer, and biogas, where the biogas is used in photovoltaic greenhouse for growing duckweed and algae, and as fuel, and (d) purifying the biogas, pumping water and storing the water in clean water storage tanks which is useful for pasture and crop cultivation, or processing water through water treatment equipment which is distributed through network for net production of livestock and poultry drinking water and solar-heated drinking system. The photovoltaic greenhouse has solar panels in roof which converts solar energy into electricity using solar energy storage systems, and has temperature of 31-32 degrees C. The biogas is purified by passing the biogas to duckweed and algae growing pond, preferably first duckweed pool for 4 days, second duckweed pool for 5 days, and third duckweed pool for 6 days. In steps (a) and (b), the precipitation is performed for 24-48 hours. The photovoltaic greenhouse cultivation is performed for 15 days, and reduces nitrogen to 85-87% and total phosphorus to 95-97%, and produces dry duckweed having 52.9% starch content. The anaerobic fermentation is performed by adding 1.5% sodium hydroxide to the liquid, standing the mixture for 2 days, adding hydrochloric acid to the mixture, adjusting pH of the mixture to 7.2, passing liquid portion into anaerobic fermentation tank, inoculating 35 vol.% activated sludge anaerobic inoculum into the tank, preparing anaerobic broth comprising 10% bacteria complex comprising 4 different kinds of strain and fermenting the mixture at 15-35 degrees C for 48 hours, where the anaerobic broth comprises 35 wt.% Cellulomonas, 40 wt.% Rhodopseudomonas palustris, 20 wt.% Trichoderma harzianum, 5 wt.% yeast, 2 wt.% glucose, 2 wt.% peptone, 2 wt.% agar, 0.1 wt.% vitamin B, 0.15 wt.% potassium dihydrogen phosphate and 0.1 wt.% disodium hydrogen phosphate and has pH of 7.